50 Years of the Turbidite Paradigm (Shanmugam, 2000)

Marine and Petroleum Geology 06 "1999# 174Ð231

9153!7061:99:, ! see front matter Þ 1999 Elsevier Science Ltd[ All rights reserved[PII] S9153!7061 "88#99900!1

49 years of the turbidite paradigm "0849sÐ0889s#] deep!waterprocesses and facies models*a critical perspective

G[ Shanmugam�Mobil Technology Company\ PO Box 549121\ Dallas\ TX 64154!9121\ USA

Received 08 June 0887^ received in revised form 01 March 0888^ accepted 10 March 0888

Abstract

Under the prevailing turbidite paradigm\ the term {turbidite| "i[e[\ deposits of turbidity currents with Newtonian rheology andturbulent state# is used very loosely and is commonly applied to deposits of debris ~ows with plastic rheology and laminar state[ Forexample\ because {high!density turbidity currents| are de_ned on the basis of three di}erent concepts "i[e[\ ~ow density\ grain size\and driving force#\ there are no consistent criteria for recognition of their deposits[ As a result\ deep!water massive sands of debris!~ow origin are routinely misinterpreted as high!density turbidites[ The concept of waxing ~ow as a type of turbidity current isproblematic because waxing ~ows are de_ned on the basis of velocity\ not on ~uid rheology and ~ow state[ The waxing!~ow conceptallows inversely graded sands to be misinterpreted as turbidites[ Perhaps\ the most problematic issue is the use of alluvial channeltraction bed forms observed in ~ume experiments as the analog for the _ve divisions of the Bouma Sequence "i[e[\ classic turbiditesdeposited from suspension#[ This is because ~ume experiments were conducted under equilibrium ~ow conditions\ whereas naturalturbidity currents deposit sediment under disequilibrium waning ~ow conditions[ This and other problems of deep!water processesand facies models are addressed in this paper from the author|s personal perspective[ Classi_cation of sediment!gravity ~ows intoNewtonian ~ows "e[g[\ turbidity currents# and plastic ~ows "e[g[\ debris ~ows#\ based on ~uid rheology and ~ow state\ is a meaningfuland practical approach[ Although popular deep!water facies models are based on transport mechanisms\ there are no standardcriteria in the depositional record to reliably interpret transport mechanisms[ According to existing turbidite!facies models\ an idealturbidite bed\ which has normal grading\ with gravel! to mud!size particles should contain a total of 05 divisions[ However\ no onehas ever documented a complete turbidite bed with 05 divisions in modern or ancient deposits[ Recognition of units deposited bydeep!water bottom currents "also referred to as contour currents# is di.cult[ Traction structures are good indicators of bottom!current reworking\ but distinguishing deposits of bottom currents from deposits of overbanking turbidity currents is di.cult eventhough it has important implications for developing depositional models for hydrocarbon exploration and production[ I considersandy debris ~ows to be the dominant process responsible for transporting and depositing sands in the deep sea[ Experiments onsandy debris ~ows suggest that low clay content "as little as 0)# is su.cient to provide the strength necessary for sandy debris ~ows[Deposits of experimental sandy debris ~ows are characterized by massive sand\ sharp upper contacts\ ~oating clasts\ inverse grading\normal grading with clasts\ and water!escape structures[ As a counterpart to turbidite!dominated fan models suited for basinalsettings\ a slope model is proposed that is a debris!~ow dominated setting with both non!channelized and channelized systems[Contrary to popular belief\ deposits of sandy debris ~ows can be thick\ areally extensive\ clean "i[e[\ mud poor#\ and excellentreservoirs[ High!frequency ~ows tend to develop amalgamated debris!~ow deposits with lateral connectivity and sheet!like geometry[Submarine!fan models with turbidite channels and lobes have controlled our thinking for nearly 24 years\ but I consider that thesemodels are obsolete[ The suprafan lobe concept was in~uential in both sedimentologic and sequence!stratigraphic circles because itprovided a basis for constructing a general fan model and for linking mounded seismic facies with sheet!like turbidite sandstones[However\ this concept recently was abandoned by its proponent\ which has left the popular sequence!stratigraphic fan models witha shaky foundation[ A paradigm shift is in order in the 10st century[ This shift should involve the realization that thick deep!watermassive sands are deposits of debris ~ows\ not {high!density turbidites|[ However\ there are no standard vertical facies models thatcan be applied universally for either turbidites\ contourites\ or sandy debris ~ows[ Science is a journey\ whereas facies modelsterminate that journey and become the _nal destination[ Þ 1999 Elsevier Science Ltd[ All rights reserved[

Keywords] Turbidity currents^ Turbidite paradigm^ Sandy debris ~ows^ Submarine!fan models

� Tel[] ¦0!103!840!2098^ fax] ¦0!103!894!6947[E!mail address] shanÐshanmugamÝemail[mobil[com

G[ Shanmuàm : Marine and Petroleum Geolo`y 06 "1999# 174Ð231175

0[ Introduction

The underlying theme of the turbidite paradigm is thatturbidity currents and their deposits "i[e[\ turbidites# arethe fundamental building blocks of deep!water depo!sitional systems[ The turbidite paradigm\ which is mani!fested in the form of various turbidite facies models "e[g[\Bouma\ 0851^ Mutti + Ricci Lucchi\ 0861\ 0864^ Walker\0867^ Stow + Shanmugam\ 0879^ Lowe\ 0871#\ has beenthe single most in~uential factor in directing our thinkingon deep!water research during the past 49 years[ Thisskewed emphasis on turbidites has left us with manybasic problems that are important not only to our basicscienti_c need to understand deep!water processes andproducts\ but also in exploring and producing deep!waterreservoirs\ targets that are becoming increasingly impor!tant as we approach the 10st century[

The current trend in both academia and the petroleumindustry is to study the reservoir architecture of deep!water sands without paying much attention to the depo!sitional processes that emplaced these sands[ This is anunhealthy trend because reservoir architecture is largelythe product of depositional processes[ Thus\ reservoirarchitecture "large scale# cannot be understood withoutunderstanding the processes "small scale# that createdthat architecture[ In addition\ a clear understanding ofdepositional processes is the key to "0# constructing ameaningful depositional model\ and "1# establishing sanddistribution[ The primary purpose of the following criti!cal review is to highlight the problems associated withconcepts of deep!water processes and related faciesmodels[ Speci_c objectives are the following]

0[ To re~ect on the history of deep!water research dur!ing the past 49 years[

1[ To stress the value of rheologic classi_cation of sedi!ment!gravity ~ows[

2[ To discuss theoretical and experimental aspects ofsandy debris ~ows[

3[ To evaluate the importance of bottom currents cre!ated by processes other than downslope gravity!induced ~ows[

4[ To assess the validity of the concepts of {high!densityturbidity currents| and {traction carpets|[

5[ To critique turbidite and contourite facies models[6[ To review the status of submarine!fan models[7[ To show the link between suprafan!lobe model and

basin!~oor fan model[8[ To discuss the validity of seismic facies and geo!

metries of deep!water systems for interpreting deep!water processes[

09[ To emphasize the current crisis that involves ques!tioning of the very foundation of the turbidite para!digm "e[g[\ Shanmugam\ 0885a\ 0886a#\ andabandonment of popular fan models "Normark\0880^ Walker\ 0881a#[

Fig[ 0[ The term {deep!water| is used in this paper to refer to bathyalwater!depth environments "×199 m# occurring seaward of the con!tinental shelf break on the slope\ and basin where sediment!gravityprocesses "slides\ slumps\ debris ~ows\ and turbidity currents#\ andbottom currents are the dominant depositional mechanisms[ In pet!roleum exploration and production\ the term {deep!water| is used withtwo di}erent meanings[ "0# To denote the deep!water depositional ori!gin of the reservoir\ even if the drilling for this reservoir commencesfrom the shelf "e[g[\ Well A#\ and "1# to denote the deep!water drillingdepths "e[g[\ Well B#\ even if the target reservoir is of shallow!waterorigin[ Gravel symbol�reservoirs of shallow!water origin[ Sand sym!bol�reservoirs of deep!water origin[

00[ To assess the problem of mud matrix in deposits ofturbidity currents and debris ~ows[

01[ Finally\ to present a depositional model for debris!~ow dominated slope systems[

By design\ this article is a cumulative expression of mypersonal views\ observations and research based largelyon my papers I have published since the 0869s "e[g[\Shanmugam + Benedict\ 0867^ Shanmugam\ 0879\ 0889\0885a\ 0886a#[ Although I have cited too many of myown papers\ this super~uity is necessary to keep track ofmy evolutionary thought process during the past 14 years[By choice\ this paper is a blend of advocacy\ auto!biography\ bibliography\ history\ personal odyssey\ phil!osophy\ psychology\ rheology\ and a lot of deep!watergeology[

The term {deep!water| is used here to refer to bathyalwater!depth environments "×199m# occurring seawardof the continental shelf break on the continental slope\rise\ and basin where sediment!gravity processes "slides\slumps\ debris ~ows\ and turbidity currents#\ and bottomcurrents are the dominant depositional mechanisms[ Inpetroleum exploration and production\ the term {deep!water| is used to convey two di}erent meanings[ "0# Mostgeologists would use the term {deep water| to convey thedeep!water depositional origin of the buried reservoir\even if the drilling for this reservoir commences from theshelf "e[g[\ Fig[ 0\ Well A#[ "1# Drilling engineers would

G[ Shanmuàm : Marine and Petroleum Geolo`y 06 "1999# 174Ð231 176

use the term to denote the deep!water drilling depths\even if the buried reservoir is of shallow!water origin"Fig[ 0\ Well B#[

1[ Progress in science

The conventional view is that science progresses ina continuous and cumulative manner[ However\ Kuhn"0869# argued that science does not proceed in a con!tinuous and cumulative manner\ but rather by periods ofscienti_c revolutions "times when old ideas are rejected#followed by periods of normal science "times when newideas are introduced and adopted#[ Kuhn|s stages ofscienti_c development are] "0# early random obser!vations\ "1# _rst paradigm\ "2# crisis\ "3# revolution\ and"4# mopping!up operations or normal science[ Turbiditefacies models may be considered to represent the normalscience stage of Kuhn[ Once this _nal stage or normalscience is achieved "i[e[\ the paradigm#\ scientists enjoy asense of con_dence as well as comfort[ This comfort oftenleads to complacency[ In this regard\ Kuhn "0869# hasargued that]

0[ The paradigm forces scientists to force!_t nature intopreconceived models of the paradigm[

1[ The paradigm encourages scientists to ignore data thatdo not _t the paradigm[

2[ The paradigm discourages scientists from inventingnew theories[

3[ The paradigm makes scientists intolerant of new the!ories invented by others[

I agree with Kuhn|s "0869# views based on my own experi!ence in deep!water research during the past 14 years[For example\ I\ in colloboration with several co!workers"Shanmugam et al[\ 0884a#\ have recently reinterpretedseveral deep!water massive sand reservoirs in the NorthSea as the deposits of sandy debris ~ows[ These depositswere previously interpreted as turbidites by other workers"e[g[\ Newman\ Leeder\ Woodru} + Hatton\ 0882#[Shanmugam et al[ "0884a# have also shown howsequence!stratigraphic models in~uenced geoscientists toforce!_t geologic data into preconceived basin!~oor fanmodels[ In line with Kuhn|s "0869# concept "see item è 3above#\ Hiscott et al[ "0886# were intolerant of our newtheories and stated that {{We therefore reject the para!digm of Shanmugam et al[ "0884# [ [ [|| In response\ Shan!mugam\ Bloch\ Damuth and Hodgkinson "0886# pointedout that Hiscott et al[ "0886# presented no evidence thatthey had examined the cores interpreted by us and thusthey had no _rst hand information about the data setused in our study[ Because of this we believe that theircritique should not be given any credence[

Throughout history\ the geologic community has beenknown for its intolerance of new observations and theor!

ies[ A well known example is the long!standing objectionto the concept of long runout landslides "the term {land!slide| includes debris ~ows\ lique_ed ~ows\ grain ~ows\and other mass movements in both subaerial and suba!queous environments#[ This objection was based on theconventional wisdom that the runout distance of a land!slide equals its vertical fall distance[ Although there aremany documented cases of landslides "e[g[\ submarineslides in Hawaii with more than 199 km of runout dis!tances*see Hampton\ Lee and Locat "0885#] the 0770Elm slide in Switzerland^ the 0892 Frank slide in Canada^the 0869 Earthquake generated debris ~ows in Peru^ andthe 0874 volcanic mud ~ows in Colombia that killed13\999 people# with long runout distances "up to 099times their vertical fall# and high speeds "up to 219 km:h#\the geologic community opposed such concepts becausethere were no known mechanisms to explain why theselandslides traveled so far and so fast "The Learning Chan!nel\ 0886#[ There are at least 19 documented theories thatattempt to explain this mechanical paradox\ such as\cushion of compressed air beneath the slide "Shreve\0857#\ shearing of granular ~ows "Campbell\ 0889#\ hyd!roplaning of subaqueous debris ~ows "Mohrig\ Whipple\Hondzo\ Ellis + Parker\ 0887#\ and the acoustic ~u!idization theory proposed by Melosh "see The LearningChannel\ 0886#[ A major turning point on this issue hadoccurred on 07 May\ 0879 when the eruption of MountSt[ Helens in the US generated impressive long runoutlandslides that were captured on videotapes "see TheLearning Channel\ 0886#[ The lesson here is that weshould not simply reject a new observation or theorybecause of a lack of precedents[ New observations andtheories cannot have precedents[ In an observational sci!ence like geology\ new observations should be encour!aged\ not discouraged[

Perhaps\ the best known example is the rejection ofAlfred Wegener|s theory of {continental drift| by thegeologic community in the 0819s and 0829s because therewere no established mechanisms to explain the {driftingcontinents|[ Bullard "0864# o}ered the most insightfulanswer to the question\ {{why the geologic communityrejected Wegener|s theory for so long<|| {{It is easy tosee||\ Bullard "0864# explained\{{why there was suchstrong opposition to Wegener in the 0819s and 0829s[ Ifweak or fallacious arguments are mixed with strong ones\it is natural for opponents to refute the former and tobelieve that the whole position has been refuted[ There isalways a strong inclination for a body of professionals tooppose an unorthodox view[ Such a group has a con!siderable investment in orthodoxy] they have learned tointerpret a large body of data in terms of the old view\and they have prepared lectures and perhaps writtenbooks with the old background[ To think the whole sub!ject through again when one is no longer young is noteasy and involves admitting a partial misspent youth[Further\ if one endeavors to change one|s views in mid!


career\ one may be wrong and be shown to have adopteda specious novelty and tried to overthrow a well!foundedview that one has oneself helped to build up[ Clearly it ismore prudent to keep quiet\ to be a moderate defenderof orthodoxy\ or to maintain that all is doubtful\ sit onthe fence\ and wait in statesmanlike ambiguity for moredata "my own line till 0848#[{{

The geologic community did reverse its position on thisissue when paleomagnetic evidence derived from polar!wandering studies "Runcorn\ 0851# and sea!~oor mag!netic anomalies "Vine and Mathews\ 0852# began to pro!vide irrefutable evidence of continental drift and {sea!~oor spreading|[

Bullard|s "0864# humorous analysis is quite _tting tothe issues of the turbidite paradigm today[ Consideringthe monumental e}orts that went into promoting tur!bidite systems and submarine fans in the form of journalarticles\ books\ research symposiums\ short courses\ coreworkshops\ and _eld trips\ it is no surprise that manyin the geologic community\ especially in industry\ arevehemently opposing any critique of the turbidite para!digm[ However\ I believe that once the initial rage ofemotions over the critique subsides\ the intellect will pre!vail[

Throughout the 0879s and 0889s\ I have been ham!mering away at the negative in~uences of the turbiditeparadigm on deep!water research "e[g[\ Shanmugam\0889\ 0885a\ 0885b\ 0886a^ Shanmugam and Moiola\0874\ 0877\ 0880\ 0883\ 0884\ 0886^ Shanmugam\Damuth + Moiola\ 0874a^ Shammugam\ Moiola +Damuth\ 0874b^ Shanmugan et al[\ 0884a\ 0885\ 0886#[Finally\ the geologic community appears to be respond!ing to my criticism of the turbidite paradigm as the Amer!ican Association of Petroleum Geologists Bulletin "0886\vol[ 70\ p[ 338Ð380\ 551Ð561# published a total of sixdiscussions and replies on my papers and at the 0886American Association of Petroleum Geologists AnnualConvention in Dallas\ a formal debate was held toaddress many of the issues of deep!water processes andfacies models "moderator] H[ E[ Clifton^ panelists] A[ H[Bouma\ D[ R[ Lowe\ J[ E[ Damuth\ G[ Parker + G[Shanmugam#[

In its 0886 Geoscience Highlights issue\ Geotimesobserved\{{Turbidites hit the fan after Shanmugam andcolleagues reinterpreted most of them as sandy debris~ows because reversely graded or ungraded bases in{most| turbidites imply settling hindered by yield strength[This yield strength supposedly implies laminar plastic~ow\ whereas turbulent ~ow should cause unhinderedsettling and normal grading[ {High!density turbidity cur!rent| becomes an oxymoron\ and {turbidite| would be asoverextended as {greywacke|[{{ "Wells\ 0887#[

In responding to my critique of the {Bouma Sequence|"Shanmugam\ 0886a#\ Miall "0888# commented\{{But it isprecisely because we have in our minds a good conceptof what a {true| Bouma turbidite should look like\ that

we can readily appreciate how far o} the track manysedimentological descriptions and interpretations havestrayed\ when someone like Shanmugam comes alongand brings us up short with di}erent observations[ Itturns out that many deep!marine sands may not be tur!bidites at all[||

Hopefully\ this debate will continue and will resultin a better understanding of deep!water processes anddepositional systems[

2[ Fifty years of the turbidite paradigm

At this point I believe it is useful to re~ect on the past49 years of the turbidite paradigm to capture what wehave learned\ and to determine what have we missed\ andwhat needs to be done in the future[ A philosophicalhistory of the turbidite concept from 0779 to 0862 is givenby Walker "0862#[ Historical development of the mainconcepts in the study of deep!water clastic sedimentsfrom 0761 to 0874 is discussed by Stow "0874#[ Bench!mark papers on deep!marine sedimentation from 0849 to0869 are listed by Pickering\ Hiscott and Hein "0878#[Sanders and Friedman "0886# provided a thoughtfulreview of petroleum exploration in deep!water depositswith special emphasis on historical perspective\ processsedimentology\ and the importance of mud in turbidites[

The year 0837 may be considered to mark the adventof the turbidite paradigm[ At the 07th International Geo!logical Congress "held in London\ UK# in 0837\ Mig!liorini discussed the origins of graded bedding by densitycurrents\ Shepard showed underwater photographs ofsteep\ massive walls of submarine canyons\ and Kuenendiscussed the erosive potential of high!density currents increating submarine canyons "see Friedman + Sanders\0886\ for a historical review#[ Prior to 0837\ the geologiccommunity was very skeptical of the importance of den!sity currents "i[e[\ turbidity currents# in eroding sub!marine canyons and depositing graded beds in the deepsea[ Until 0849 when Kuenen and Migliorini "0849# pub!lished their classic paper {Turbidity currents as a causeof graded bedding|\ the geologic community generallybelieved that the deep sea was a tranquil realm free ofcurrent activity where only mud slowly accumulated frompelagic settling "Friedman + Sanders\ 0886#[ However\systematic shallow coring of continental margin andabyssal!plain sediments beginning in the 0839s con_rmedthe existence of turbidity currents and related gravity!controlled deposition of sediment in the deep sea[ Sincethen the occurrence of turbidite sands in deep!waterstrata has gained global acceptance[ Today\ however\ theturbidite paradigm has gone to the other extreme in somecircles of the geologic community^ which now routinelyrely on model!driven interpretations that envision nearlyall deep!water sands as true turbidites deposited on sub!marine fans[ I _nd it remarkable that during a period of


Fig[ 1[ Important contributions to deep!water research made duringthe past 49 years[ An expanded list is given in the text[ Note di}erencesbetween Walker "0862#\ Stow "0874#\ and Shanmugam "0887b# in per!spectives on the advent of the normal science stage[ See text for detaileddiscussion[

just 49 years\ geologists went from a state of caution toa state of complacency regarding turbidity currents andtheir deposits[ In this paper\ I have attempted to capturethe general trend of deep!water research during the past49 years "Fig[ 1#[ The following is an expanded list ofpioneering studies\ milestones\ selected contributions\and events along that general trend\ but is by no meansa comprehensive bibliography]

2[0[ Pre!0849s

, First description of density currents in Swiss Lakesreported "Forel\ 0776#

, Tranquil deep!sea realm receiving only pelagic claysperceived "Murray + Renard\ 0780#

, Cable breaks by submarine avalanches along the sub!marine canyon axis recognized "Milne\ 0786#

, First sequence of structures\ which would later become

the Bouma Sequence\ recognized in the US "Sheldon\0817#

, Sequence of structures with _ve divisions\ which wouldlater become the Bouma Sequence\ recognized in Italy"Signorini\ 0825#

, In a pioneering study\ the possibility of occurrence ofdeep bottom currents in the Atlantic Ocean suggested"Wust\ 0825#

, Deep!water origin of {graded facies| _rst proposed"Bailey\ 0825#

, Origin of submarine canyons through erosion by den!sity currents advocated "Daly\ 0825#

, Currents in submarine canyons _rst noted "Stetson\0825^ Shepard\ Revelle + Dietz\ 0828#

, First experiments on density currents to test Daly|shypothesis conducted "Kuenen\ 0826#

, Density currents in Lake Mead observed "Grover +Howard\ 0827#

, The term turbidity current introduced "Johnson\ 0827#, Graded sand from deep!sea cores described "Bramlette

+ Bradley\ 0839#, Density currents as agents for transporting sediments

recognized "Bell\ 0831#

2[1[ 0849s

, First experiments on turbidity currents of high densityconducted "Kuenen\ 0849#

, Turbidity current origin of graded bedding\ which for!med the foundation of the turbidite paradigm\ pro!posed "Kuenen + Migliorini\ 0849#

, Criteria for recognition of slope deposits proposed"Rich\ 0849#

, Transported shallow water fauna in deep!watersequences recognized "Natland + Kuenen\ 0840#

, Mass movements in heads of modern submarine can!yons documented "Shepard\ 0840#

, Association of ancient debris ~ows and slides withturbidites recognized "Doreen\ 0840#

, Cable breaks by Grand Banks slump suggested"Heezen + Ewing\ 0841^ Heezen + Drake\ 0853#

, Turbidites from modern oceans recovered "Heezen +Ewing\ 0841^ Ericson\ Ewing + Heezen\ 0841#

, Existence of dispersive pressure by colliding grains inhigh!concentration dispersions\ which would later betermed {grain ~ows|\ proposed "Bagnold\ 0843#

, First detailed account of modern submarine fans o}California reported "Menard\ 0844#

, The term turbidite for the deposit of a turbidity currentintroduced "Kuenen\ 0846#

, Importance of detrital mud matrix in turbidite sand!stone reported "Pettijohn\ 0846#

, Debris!~ow origin of pebbly mudstone proposed"Crowell\ 0846#

, Classi_cation for landslide types and processes pro!posed "Varnes\ 0847#


, The term {~uxoturbidites| for deposits of transitional~ows between slumping and turbidity currents intro!duced "Kuenen\ 0847^ Dzulynski\ Ksiazkiewicz +Kuenen\ 0848#

, Canyon!fan systems vs slope!apron systems described"Gorsline + Emery\ 0848#

, Concept of turbidity currents critiqued "Ten Haaf\0848#

, Tectonic control of deep!sea sedimentation in con!tinental margins discussed "Drake\ Ewing + Sutton\0848#

, High!concentration granular wedge at the base of adepositing turbidity current\ which would later betermed {traction carpet|\ proposed "Hsu\ 0848#

2[2[ 0859s

, High silt and clay content "02[4Ð23[4)# of turbiditesandstone recognized "Sullwold\ 0859#

, Hydrocarbon reservoirs of {turbidite| origin emphas!ized "Sullwold\ 0850#

, The _rst vertical facies model of turbidites\ which hasbecome known as the {Bouma Sequence| formulatedfrom the Annot Sandstone outcrops in SE France"Bouma\ 0851#

, In a pioneering study\ a clear distinction betweenalong!slope bottom currents and down!slope turbiditycurrents made "Murphy + Schlanger\ 0851#

, Outcrops of the Martinsburg ~ysch\ central Appal!achians described "McBride\ 0851#

, The term {traction carpet| for ~owing!grain layers atthe base of a depositing turbidity current introduced"Dzulynski + Sanders\ 0851#

, Auto!suspension of transported sediment in turbiditycurrents proposed "Bagnold\ 0851#

, Diagenetic origin of mud matrix in greywacke sug!gested "Cummins\ 0851#

, First classi_cation of sediment!gravity ~ows based on~uid rheology proposed "Dott\ 0852#

, Interpretation of ~uid mechanics from sedimentarystructures discussed "Sanders\ 0852#

, The importance of slumps\ debris ~ows\ grain ~ows\and lique_ed ~ows in the origin of the Annot Sand!stone\ SE France\ discussed "Stanley\ 0852#

, First collection of papers on turbidite research pub!lished "Bouma + Brouwer\ 0853#

, Importance of non!gravity!driven bottom currents inredistributing sediments in modern oceans discussed"Hubert\ 0853#

, Modern Congo submarine canyon\ west Africa studied"Heezen\ Menzies\ Schneider\ Ewing + Granelli\0853#

, A book on sedimentary features of ~ysch published"Dzulynski + Walton\ 0854#

, Hydrodynamic interpretation of the {BoumaSequence|\ based on comparison with traction struc!

tures produced in experimental alluvial channels\ pro!posed "Harms + Fahnestock\ 0854^ Walker\ 0854#

, The meaning of turbidity currents as opposed to othergravity!driven processes discussed "Sanders\ 0854#

, Importance of non!gravity driven bottom currents inthe Ouachita ~ysch\ Pennsylvanian\ Arkansas andOklahoma discussed "Klein\ 0855#

, First ~ume experiments in understanding body andhead dynamics of turbidity currents conducted "Mid!dleton\ 0855#

, Worldwide examples of modern submarine canyonsand valleys compiled "Shepard + Dill\ 0855#

, The importance of parallel!to!slope thermohaline andwind!driven currents "i[e[\ bottom currents# in the deepsea recognized and the term contour current introduced"Heezen\ Hollister + Ruddiman\ 0855^ Hollister\ 0856#

, For the _rst time\ the term contourite for the depositof a contour current introduced "Hollister\ 0856#

, Sequence of structures in turbidites studied "Walton\0856#

, Paleocurrent patterns in the Ouachita ~ysch\ Pennsyl!vanian\ Oklahoma documented "Briggs + Cline\ 0856#

, Grain ~ow deposits\ California discussed "Stau}er\0856#

, Details of a mid!sized modern submarine fan o} Ore!gon studied "Nelson\ 0857#

, Detailed outcrop description of a ~ysch\ Canada dis!cussed "Enos\ 0858#

, Problems associated with turbidity current conceptsdiscussed "Van der Lingen\ 0858#

2[3[ 0869s

, First model for modern submarine fan including sup!rafan!lobe concept introduced "Normark\ 0869#

, The Pennsylvanian Ouachita ~ysch\ Oklahoma studied"Cline\ 0869#

, Large mass!transport deposits "e[g[\ slumps# on themodern Mississippi Fan\ Gulf of Mexico recognized"Walker + Massingill\ 0869#

, Trace fossils in the Ouachita ~ysch\ Pennsylvanian\Oklahoma discussed "Chamberlain\ 0860#

, Deep!sea processes revealed by sea!~oor photographspublished "Heezen + Hollister\ 0860#

, First detailed seismic study of the architecture\ growthpatterns\ and sedimentation processes of a large mod!ern deep!sea fan*Bengal Fan\ Bay of Bengal*dis!cussed "Curray + Moore\ 0860#

, Hydraulic jumps in turbidity currents discussed"Komar\ 0860#

, Criteria for recognition of deposits of coarse!grainedhigh!concentration ~uids developed "Fisher\ 0860#

, Modern slumps on continental slopes of 0Ð3> reported"Lewis\ 0860#

, First model of depositional lobe for ancient submarinefans introduced "Mutti + Ghibaudo\ 0861#


, First channel!lobe submarine!fan model based on out!crop studies in Italy and Spain introduced "Mutti +Ricci Lucchi\ 0861#

, Turbidite origin of laminated mudstone discussed"Piper\ 0861#

, Sedimentation processes\ architecture\ and growth pat!tern of a small modern deep!sea fan*Navy Fan*onan active continental margin based on seismic andsediment cores discussed "Normark + Piper\ 0861#

, First major experiments on subaqueous debris ~owsconducted "Hampton\ 0861#

, Liquefaction to account for the structureless appear!nace of deep!water conglomerates invoked "Hendry\0862#

, Historical account of the turbidite paradigm reviewed"Walker\ 0862#

, An important collection of papers on deep!water pro!cesses and facies models published "Middleton +Bouma\ 0862#

, First classi_cation of sediment!gravity ~ows based onsediment!support mechanisms proposed "Middleton +Hampton\ 0862#

, Properties of submarine canyons compiled "Whitaker\0863#

, Turbiditic and non!turbiditic mudstone distinguished"Hesse\ 0864#

, For the _rst time\ the concept of {sandy debris ~ows|with low clay content discussed "Hampton\ 0864#

, A classi_cation of laminar!mass ~ow into grain ~ow withwater as interstitial ~uid and slurry ~ow with water!mudslurry as interstitial ~uid proposed "Carter\ 0864#

, Detailed seismic study of the architecture\ growth pat!terns\ and sedimentation processes of a large moderndeep!sea fan*Amazon fan*discussed "Damuth +Kumar\ 0864#

, First turbidite facies scheme for interpreting deposits ofsubmarine fans proposed "Mutti + Ricci Lucchi\ 0864#

, Detached lobe concept for submarine fans introduced"Mutti + Ricci Lucchi\ 0864#

, The use of modern Bengal Fan as an analog for thePennsylvanian Ouachita ~ysch proposed "Graham\Dickinson + Ingersoll\ 0864#

, Depositional cycles in turbidites discussed "RicciLucchi\ 0864#

, Classi_cation of very high!resolution "2[4 kHz sonar#seismic facies to study deep!sea sedimentation pro!cesses proposed "Damuth\ 0864#

, Distribution of large slides and debris ~ows on moderncontinental margins reported "Jacobi\ 0865^ Embley\0865#

, Glacio!eustatic control of turbidite\ hemipelagic andother terigenous sediment deposition on continentalmargins proposed "Damuth\ 0866#

, Facies geometry of turbidite reservoirs\ lower Pliocene\Ventura Field\ California discussed "Hsu\ 0866#

, First seismic stratigraphic models for sedimentation

on passive continental margins introduced "Vail\ Mit!chum + Thompson\ 0866#

, First side!scan sonar surveys of modern submarinecanyons\ channels\ and slope features reported "Beld!erson + Kenyon\ 0865^ Coleman + Garrison\ 0866#

, Characteristics of a large submarine slump\ SE Africadescribed "Dingle\ 0866#

, A general submarine!fan model with an emphasis onstratigraphic traps for hydrocarbon exploration pro!posed "Walker\ 0867#

, A collection of papers on submarine canyons\ fans\and trenches published "Stanley + Kelling\ 0867#

, Fine!grained turbidites discussed "Piper\ 0867#, Detailed seismic study of the architecture\ growth pat!

terns\ and sedimentation processes of a large moderndeep!sea fan*Mississippi Fan*discussed "Moore\Starke\ Bonham + Woodbury\ 0867#

, A model for _ne!grained debris ~ows\ Ordovician\Tennessee introduced "Shanmugam + Benedict\ 0867#

, Tectonic signi_cance of distal turbidites discussed"Shanmugan + Walker\ 0867#

, Up! and down!bottom currents in submarine canyons\induced by tidal forces\ documented "Shepard + Mar!shall\ 0867^ Shepard\ 0868#

, Petrology of the modern Bengal Fan\ Bay of Bengalstudied "Ingersoll + Suczek\ 0868#

, Dipmeter and log motifs of submarine channels andlobes introduced "Selley\ 0868#

, Fine!grained turbidites and contourites distinguished"Stow\ 0868#

, Modern and ancient contourites reviewed "Stow +Lovell\ 0868#

, A classi_cation of sediment!gravity ~ows based on rhe!ology and sediment!support mechanism introduced"Lowe\ 0868#

, Mounded seismic geometry of the Frigg fan\ lowerEocene\ Frigg Field\ North Sea discussed "Heritier\Lossel + Wathne\ 0868#

, Mass movement processes reviewed "Nardin\ Hein\Gorsline + Edwards\ 0868#

, Mass movements on carbonate slopes discussed"Cook\ 0868#

, Sizes of submarine slides documented "Woodcock\0868#

2[4[ 0879s

, Rhythms in _ne!grained turbidites\ Ordovician\ Ten!nessee studied "Shanmugam\ 0879#

, Sand!layer geometry of modern basin!~oor turbiditescompared "Pilkey\ Locker + Cleary\ 0879#

, A vertical facies model for _ne!grained turbidites intro!duced "Stow + Shanmugam\ 0879#

, Submarine!fan concepts debated "Nilsen\ 0879#, DSDP "Deep Sea Drilling Project# results summarized

"Warme\ Douglas + Winterer\ 0870#


, Turbidites from DSDP compiled "Kelts + Arthur\0870#

, Existence and importance of very large mass!transportdeposits on the modern Amazon Fan\ EquatorialAtlantic discussed "Damuth + Embley\ 0870#

, GLORIA "Geological Long Range Inclined Asdic#side!scan sonar survey reviewed "Laughton\ 0870#

, Petroleum source beds of deep!marine origin discussed"Kvenvolden\ 0870#

, Data in support of eustatic control of turbidites andwinnowed turbidites compiled "Shanmugam +Moiola\ 0871#

, A collection of papers on deep!water models for strati!graphic traps published "Tillman + Ali\ 0871#

, First remote acoustic detection of a modern {turbiditycurrent|\ Rupert Inlet\ British Columbia claimed "Hay\Burling + Murray\ 0871#

, Deep!water facies in subduction complexes discussed"Underwood + Bachman\ 0871#

, A theoretical model for deposits of {high!density tur!bidity currents| proposed "Lowe\ 0871#

, Four types of ~ow transformations in sediment!gravity~ows proposed "Fisher\ 0872#

, A collection of papers on the shelfbreak processes andfacies published "Stanley + Moore\ 0872#

, Hydrocarbon!bearing sands of depositional lobeorigin\ lower Pliocene\ Italy discussed "Casnedi\ 0872#

, Modern Storegga Slide\ o}shore Norway discussed"Bugge\ 0872#

, The use of managanese distribution in recognizingancient deep!water lithofacies documented "Shan!mugam + Benedict\ 0872#

, Highly meandering distributary channels on moderndeep!sea fans during GLORIA side!scan sonar surveyof the Amazon Fan\ Equatorial Atlantic discovered"Damuth et al[\ 0872^ Damuth\ Flood\ Kowsmann\Gorini + Belderson\ 0877#

, First COMFAN "COMmitte on FANs# Meeting"Pittsburgh\ Pennsylvania\ 0871#*realization of com!plexity of modern and ancient submarine fans and thatno general model is applicable to describe all fans*convened "Bouma\ 0872#

, Spectrum of processes between cohesive and cohesion!less debris ~ows discussed "Shultz\ 0873#

, Debris!~ow dynamics in subaerial environments dis!cussed "Costa + Williams\ 0873#

, Debris ~ows reviewed "Johnson\ 0873#, Mechanics of rapid granular ~ows reviewed "Savage\

0873#, Short course notes on modern and ancient deep!sea

fan sedimentation published "Nelson + Nilsen\ 0873#, A collection of papers on _ne!grained turbidites pub!

lished "Stow + Piper\ 0873#, Data in support of eustatic control of calciclastic tur!

bidites compiled "Shanmugam + Moiola\ 0873#, HEBBLE "High!Energy Benthic Boundary Layer

Experiment# project\ North Atlantic discussed "Hollis!ter + McCave\ 0873#

, Subaqueous slope failures in fjords documented "Syvit!ski\ 0874#

, DSDP Leg 85 "0872#*First modern submarine fan"Mississippi Fan#\ Gulf of Mexico cored "Bouma etal[\ 0874#

, Three types of turbidite systems based on sea levelcontrol proposed "Mutti\ 0874#

, Provenance of modern deep!sea sands discussed "Val!loni\ 0874#

, Submarine!ramp model\ an alternative to submarine!fan model\ proposed "Heller + Dickinson\ 0874#

, Turbidite facies scheme for interpreting submarine!fanenvironments questioned "Shanmugam et al[\ 0874a#

, Tectonic control of detached lobes in submarine fansproposed "Shanmugam + Moiola\ 0874#

, First model on seismic expression of submarine fans ina sequence!stratigraphic framework proposed "Mit!chum\ 0874#

, A classi_cation of deep!water facies proposed "Pick!ering\ Stow\ Watson + Hiscott\ 0875#

, A model for geometry of gully sands and related sandinjections\ upper Jurassic\ East Greenland proposed"Surlyk\ 0876#

, Basin!~oor fan and slope fan models in a sequence!stratigraphic framework proposed "Vail\ 0876#

, Modern and ancient turbidite systems compared"Mutti + Normark\ 0876#

, Mass wasting features on the continental slope\ Nor!thwest Europe documented "Kenyon\ 0876#

, Second COMFAN Meeting "Parma\ Italy\ 0877# con!vened "no formal publication#

, Modern and ancient submarine fans reviewed "Shan!mugam + Moiola\ 0877#

, Experiments on {high!density turbidity currents| con!ducted "Postma\ Nemec + Kleinspehn\ 0877#

, Modern examples of sediment drifts\ Argentine Basin\South Atlantic documented "Klaus + Ledbetter\ 0877#

, Mechanisms of high concentration sediment!gravity~ows\ based on ~ume study and _eld study of theAnnot Sandstone in SE France\ discussed "Oakeshott\0878#

, A book on deep!marine environments published "Pick!ering et al[\ 0878#

, The validity of the Bouma Sequence questioned "Hsu\0878#

2[5[ 0889s

, Deep!marine facies models reviewed "Shanmugam\0889#

, Rapid granular ~ows reviewed "Campbell\ 0889#, Aspects of sediment movement on steep delta slopes

discussed "Nemec\ 0889#, Mississippi Fan*_rst study of a modern fan using


standard industry multifold seismic data and to put amodern submarine fan into a sequence!stratigraphicframework*discussed "Weimer\ 0889#

, Seismic expression of submarine fans discussed "Posa!mentier + Erskine\ 0880^ Weimer + Link\ 0880#

, Submarine!fan lobe concepts critiqued "Shanmugam+ Moiola\ 0880#

, Normark|s "0869# suprafan lobe concept abandoned"Normark\ 0880#

, Walker|s "0867# general submarine!fan model aban!doned "Walker\ 0881a#

, A photographic book on turbidite sandstones issued"Mutti\ 0881#

, Dendritic channel patterns at the terminus of the Mis!sissippi Fan\ Gulf of Mexico documented "Twichell\Schwab\ Nelson\ Kenyon + Lee\ 0881#

, Deposition from turbidity currents reviewed "Mid!dleton\ 0882#

, Giant ancient sandy slides\ Antarctica documented"Macdonald\ Moncrief + Butterworth\ 0882#

, Hydrocarbon!bearing reservoirs in bottom!currentreworked sands\ Plio!Pleistocene\ Gulf of Mexicodescribed "Shanmugam\ Spalding + Rofheart\ 0882a\0882b\ 0884c#

, Reservoir sands of slump and debris ~ow origin\Norwegian North Sea documented "Shanmugam et al[\0883#

, Turbidite fan models based on grain size and feedersystem proposed "Reading + Richards\ 0883#

, A collection of papers on deformation of sedimentspublished "Maltman\ 0883#

, A collection of papers on submarine fans and turbiditesystems published "Weimer\ Bouma + Perkins\ 0883#

, ODP "Ocean Drilling Program# Leg 044 "0883#*_rstsystematic\ continuous deep coring of stratigraphicand seismic units\ architecture\ and sediment facies ofthe Amazon Fan^ con_rmation that channel!_ll "HARunits# and base of channel!levee system deposits"HARP units# are predominantly sand*documented"Flood\ Piper + Shipboard Scienti_c Party\ 0884#

, A collection of papers on reservoir characterization ofdeep!water clastic systems published "Hartley +Prosser\ 0884#

, Classic {turbidites| of Pennsylvanian Ouachita ~ysch\Arkansas reinterpreted as sandy debris ~ows "Shan!mugam + Moiola\ 0884#

, Hydrocarbon!producing sands of slump and debris~ow origin\ lower Eocene\ Frigg Field\ NorwegianNorth Sea discussed "Shanmugam et al[\ 0884a#

, Hydrocarbon!producing sands of slump and debris~ow origin\ Pliocene\ Edop Field\ o}shore Nigeriareported "Shanmugam\ Hermance\ Olaifa + Odior\0884b#

, Basin!~oor fans in a sequence!stratigraphic frameworkcritiqued "Shanmugam et al[\ 0884a\ 0885#

, Atlas of architectural style in turbidite systems pub!

lished "Pickering\ Hiscott\ Kenyon\ Ricci Lucchi +Smith\ 0884#

, A book on submarine channels published "Clark +Pickering\ 0885#

, US Continental slopes documented "Pratson + Haxby\0885#

, The concept of {high!density turbidity currents| ques!tioned and a theoretical model for sandy debris ~owspresented "Shanmugam\ 0885a#

, Perception vs[ reality in deep!water exploration dis!cussed "Shanmugam\ 0885b#

, Long runout distances of modern submarine slidesdocumented "Hampton et al[\ 0885#

, Debris!~ow deposits classi_ed "Coussot + Meunier\0885#

, Reinterpretation of classic {turbidites| as sandy debris~ows debated "Shanmugam + Moiola\ 0886^ Shan!mugam et al[\ 0886#

, The Bouma Sequence and the turbidite mind set cri!tiqued "Shanmugam\ 0886a#

, History behind dispelling the myth of sea!~oor tran!quility reviewed "Friedman + Sanders\ 0886#

, Petroleum exploration in deep!water deposits reviewed"Sanders + Friedman\ 0886#

, Physics of debris ~ows reviewed "Iverson\ 0886#, Finger!like debris ~ows on the glaciated Norwegian!

Barents Sea continental margin documented "Elverhoiet al[\ 0886#

, First experiments on subaqueous sandy debris ~owswith low clay content conducted "Marr\ Har}\ Shan!mugam + Parker\ 0886#

, Conceptual models and their uncertainties in deep!water exploration discussed "Shanmugam\ 0886c#

, First experiments demonstrating hydroplaning ofsubaqueous debris ~ows conducted "Mohrig et al[\0887#

, Modern tidal rhythmites in a deep!water estuary docu!mented "Cowan\ Cai\ Powell\ Seramur + Spurgeon\0887#

, Fossil contourites reviewed "Stow\ Faugeres\ Viana +Gonthier\ 0887#

, Fossil contourites exposed in China documented"Zhenzhong et al[\ 0887#

, Slope and base!of!slope systems reviewed "Galloway\0887#

, A book on turbidite systems of SE France published"Pickering + Hilton\ 0887#

, A book on dimensions and geometries of deep!watersystems issued "Shanmugam\ 0887a#

, A keynote talk on {49 years of the turbidite paradigm|delieverd "This paper\ Shanmugam\ 0887b#

, Turbidite facies models defended "Miall\ 0888#, International Geological Correlation Programme

"IGCP# Project 321 "0887#*Contourite Watch*tofacilitate research on contourites and bottom currentsestablished "Stow\ 0888#


, Sandy debris ~ow contributing to a long runout dis!tance of over 399 km downslope of the Canary Islandson slopes that decrease to as little as 9[94> documented"Gee\ Masson\ Watts + Allen\ 0888#

In summary\ the 0849s\ 0859s\ and 0869s were periods ofmodel building for the deposits of turbidity currents^however\ the de_nition and meaning of {turbidity cur!rents| has been debated since the mid 0859s "Sanders\0854#[ In the 0879s\ fundamental questions were raisedregarding the Bouma Sequence\ fan models\ and turbiditefacies scheme[ Furthermore\ results of COMFAN I"Bouma\ 0872# revealed that modern and ancient fansystems are much more complex than we had envisioned[In spite of these problems\ fan models with channels andlobes continued to dominate deep!water sedimentologyand sequence stratigraphy[ The 0889s have been a periodof re!evaluation and abandonment of fan models\ rein!terpretation of deep!water massive {turbidite| sands asdeposits of sandy debris ~ows\ debate over high!densityturbidity currents\ experiments on sandy debris ~ows\and contemplation of the meaning of seismic geometriesin terms of depositional facies[

2[6[ Differing perspectives on the turbidite paradigm

Di}ering scienti_c perspectives exist over the timing ofonset of the _nal science stage "i[e[\ mopping!up oper!ations\ Kuhn\ 0869# of the turbidite paradigm[ For exam!ple\ Walker "0862# suggested that the normal sciencestage of the turbidite paradigm began in 0849 "Fig[ 1#[However\ Stow "0874# suggested that the {age of order|"i[e[\ normal science stage# began in 0872[ From my per!spective\ the turbidite paradigm has always been in acrisis mode\ and the normal science stage has never beenachieved "see Fig[ 1#[ We are still in the process of learningthe fundamentals of deep!water processes and products\and we are far from solving many fundamental problems[We can never achieve a normal science stage until weclearly establish the basic principles of a scienti_c para!digm[ A possible reason that Walker "0862# and Stow"0874# expressed di}erent perspectives is because manyof the problems that came to light during the past fewyears were not fully realized when they published theirpapers[ Our perspectives tend to change with time[

2[7[ Science vs time

Just over 49 years ago\ geologists thought that thedeep!sea ~oor was a tranquil environment\ whichreceived only pelagic sediment "see review by Friedman+ Sanders\ 0886#[ We now know that in the deep sea\ theentire water column is a highly dynamic environment andthat coarse sediment can be transported hundreds ofkilometers downslope from the continental shelf edge bygravity!controlled mass!transport processes[ In addition\

deep thermohaline!induced bottom currents redistributeenormous volumes of sediment along the continentalslope\ rise and basin plains[ Although science is dynamic\changes in scienti_c concepts are not always swift[ Forexample\ just over 499 years ago\ it was still believed thatthe Earth was at the center of the universe as proposedby Ptolemy in the second century A[D[ It took nearly0499 years to prove that the Earth was not at the centerof the universe by the works of Copernicus\ Galileo\ andNewton[ Hopefully\ we can resolve the remaining deep!water problems in a shorter time span;

3[ Deep!water processes

An understanding of mechanics of deep!water pro!cesses is of critical importance in understanding the nat!ure of transport and deposition of sand in the deep!sea[ Process sedimentology serves as the fundamentalunderpinning for building depositional models[ Sedimentgravity plays an important role in transporting anddepositing sediments in deep!water environments[ Majorsediment!gravity processes include slides\ slumps\ debris~ows\ and turbidity currents[ In addition\ bottom cur!rents "contour currents# are important in reworking deep!water deposits[ Numerous schemes are in use for classi!fying sediment!gravity processes based on rheology "e[g[\Dott\ 0852#\ sediment!support mechanisms "e[g[\ Mid!dleton + Hampton\ 0862#\ or both "Lowe\ 0868\ 0871#[There are inherent problems with classi_cations based onsediment!support mechanisms alone because] "0# theseclassi_cations deal only with end!member types\ whereasin natural ~ows more than one support mechanism maybe involved\ "1# these classi_cations deal with sediment!support mechanisms only during the time of transport\whereas deposits re~ect sediment!support mechanismsduring the time of deposition\ and "2# at present\ thereare no criteria to recognize transport mechanisms fromthe depositional record[ For these reasons\ I _nd classi!fying sediment!gravity ~ows into two broad groups\namely "0# Newtonian ~ows and "1# plastic ~ows\ basedon rheology "Fig[ 2#\ is the most useful for interpretingthe origin of deep!water sands[ This classi_cation is anal!ogous to the one originally proposed by Dott "0852#[

3[0[ Newtonian ~ows

The rheology of ~uids can be expressed as a relation!ship between applied shear stress and rate of shear strain"Fig[ 2#[ Newtonian ~uids "i[e[\ ~uids with no inherentstrength#\ like water\ will begin to deform the momentshear stress is applied\ and the deformation is linear[ ForNewtonian ~uids\ the criterion for initiation of tur!bulence is the Reynolds Number\ Re "ratio between inertiaand viscous forces#\ which is greater than 1999 "Fig[ 2#[

In deep!water environments\ turbidity currents rep!


Fig[ 2[ Rheology "stress!strain relationships# of Newtonian ~uids "e[g[\ turbidity currents# and Bingham plastics "e[g[\ debris ~ows#\ compiled fromseveral sources "Dott\ 0852^ Enos\ 0866^ Pierson and Costa\ 0876^ Phillips and Davies\ 0880^ Middleton and Wilcock\ 0883#[ This graph shows thata fundamental rheological di}erence between debris ~ows "Bingham plastics# and turbidity currents "Newtonian ~uids# is that debris ~ows exhibitstrength\ whereas turbidity current do not[ In general\ turbidity currents are turbulent\ and debris ~ows are laminar in state[ From Shanmugam"0886a#[

resent Newtonian ~ows[ Newtonian rheology of turbiditycurrents has been addressed by many researchers "Dott\0852^ Nardin et al[\ 0868^ Lowe\ 0868\ 0871^ Shanmugam+ Moiola\ 0884#[ Lowe "0868# and Nardin et al[ "0868#classi_ed turbidity currents as both sediment!gravity~ows and ~uidal ~ows[ According to Oakeshott "0878#\this classi_cation is confusing because sediment!gravity~ows are ~ows in which sediment is moved by gravity\whereas ~uidal ~ows are ~ows in which ~uid is movedby gravity "see Middleton + Hampton\ 0862#[ In otherwords\ turbidity currents cannot be both sediment!grav!ity ~ows and ~uidal ~ows[ Classifying turbidity currentsas Newtonian ~ows can eliminate this confusion[

Turbulence is characteristic of Newtonian ~ows\ notplastic ~ows[ According to Middleton "0882#\ {{Turbiditycurrents are one type of sediment gravity ~ow in whichthe sediment is held in suspension by ~uid turbulence[||More importantly\ if a ~ow is laminar or non!turbulentit can no longer be considered as a turbidity current"Middleton\ 0882#[ A turbidity current is a sediment!grav!ity ~ow with Newtonian rheology and turbulent state fromwhich deposition occurs through suspension settling[

3[1[ Plastic ~ows

In contrast to Newtonian ~uids\ some naturally occur!ring materials "i[e[\ ~uids with strength# will not deformuntil yield stress has been exceeded "Fig[ 2#^ once theyield stress is exceeded the deformation is linear[ Suchmaterials with strength are considered to be Binghamplastic[ Flows that exhibit plastic rheology are termed

here plastic ~ows[ For Bingham plastics\ the criterion forinitiation of turbulence is based on both the ReynoldsNumber\ Re\ and the Bingham Number\ B "Fig[ 2#[Although some debris ~ows can develop turbulence"Enos\ 0866#\ such ~ows are not diagnostic of most debris~ows that are laminar "i[e[\ no ~uid mixing across stream!lines#[ Johnson "0869# favored a Bingham plastic rheo!logic model for debris ~ows[ Although the rheology is acomplex parameter and is di.cult to measure accurately"Phillips + Davies\ 0880#\ it is useful in distinguishingturbidity currents from other sediment!gravity ~ows[ Adebris ~ow is a sediment!gravity ~ow with plastic rheologyand lamianr state from which deposition occurs throughfreezing[ The term {debris ~ow| is used here for both theprocess and the deposit of that process[

The rheology of a sedimentÐwater mixture is governedmainly by sediment concentration and to a lesser extentby grain size and the physical and chemical properties oftransported solids "Pierson + Costa\ 0876#[ A com!pilation of published sediment concentration values ofvarious ~ow types shows that the boundary betweenNewtonian and plastic ~ows occurs at about 19Ð14) byvolume "Fig[ 3#[ The one exception is the concept of{high!density turbidity current| that has a range of valuesrepresenting both Newtonian and plastic ~ows[ There!fore\ I suggest that the concept of {high!density turbiditycurrent| is not meaningful in this rheologic classi_cationof ~ows[ Although I have distinguished low!density tur!bidity currents "i[e[\ true turbidity currents# from {high!density turbidity currents| for discussion purposes "Fig[3#\ I do not consider {high!density turbidity currents| as


Fig[ 3[ A classi_cation of subaqueous gravity ~ows\ based on ~uid rheology\ showing two general types\ Newtonian and Plastic[ This classi_cation isanalogous to a classi_cation originally advocated by Dott "0852#[ Turbidity currents are Newtonian ~ows\ whereas all mass ~ows "muddy debris~ows\ sandy debris ~ows\ and grain ~ows# are Plastic ~ows[ Turbidity currents occur only as subaqueous ~ows\ whereas debris ~ows and grain ~owscan occur both as subaerial and as subaqueous ~ows[ For purposes of comparison\ subaerial ~ows "river currents and hyperconcentrated ~ows# areincluded[ Sediment concentration is the most important property in controlling ~uid rheolgy[ High!density turbidity currents are not meaningful inthis rheologic classi_cation because their sediment concentration values represent both Newtonian and plastic ~ows^ however\ I have included themhere for discussion purposes[ Published values of sediment concentration by volume ) are] "0# river currents "0Ð4)^ e[g[\ Galay\ 0876#\ "1# low!density turbidity currents "0Ð12)^ e[g[\ Middleton\ 0856\ 0882#\ "2# high!density turbidity currents "5Ð33)^ Kuenen\ 0855^ Middleton\ 0856#\ "3#hyperconcentrated ~ows "19Ð59)^ Pierson and Costa\ 0856#\ "4# muddy debris ~ows "49Ð89)^ Coussot and Muenier\ 0885#\ "5# sandy debris ~ows"14Ð84)^ Shanmugam\ 0886a^ partly based on my reinterpretations of various processes that exhibit plastic rheology in papers by Middleton\ 0855\0856^ Wallis\ 0858^ Lowe\ 0871^ Shultz\ 0873^#\ and "6# grain ~ows "49Ð099)^ partly based on Rodine and Johnson\ 0865^ Shultz\ 0873^ Pierson andCosta\ 0876#[ Concentration values of more than 84 vol[) can be without signi_cant particle interlocking "Rodine and Johnson\ 0865#\ and therefore~ow "i[e[\ deformation of material in response to applied stress# is possible at high concentration values[ Two general modes of transport representdi}erent subaqueous ~ow types] "0# suspended mode in turbidity currents\ and "1# mass transport mode in plastic ~ows[ Bed!load transport ismeaningful only in river currents\ but not in turbidity currents because sediment is held in suspension by ~ow turbulence during transport[ Twogeneral sediment support mechanisms represent di}erent subaqueous ~ow types] "0# turbulence in turbidity currents\ and "1# cohesive strength\frictional strength\ and buoyancy in plastic ~ows[ Dispersive pressure " frictional strength# can become an important sediment support mechanism atsediment concentration values of 49Ð099) "Rodine and Johnson\ 0865#[

true turbidity currents in terms of ~uid rheology^ I con!sider them to be sandy debris ~ows "see Shanmugam\0885a#[

Mass transport processes are dominated by plasticbehavior "Nardin et al[\ 0868#[ Therefore\ I restrict theuse of the term {mass ~ows| only to plastic ~ows\ and Ido not apply the term {mass ~ows| to turbidity currents[Plastic ~ows comprise cohesive debris ~ows\ lique_ed~ows\ ~uidized ~ows\ and grain ~ows "see Lowe\ 0868\0871#[ In addition\ sandy debris ~ows "Shanmugam\0886a#\ and lique_ed cohesionless coarse!particle ~ow"Friedman\ Sanders + Kopaska!Merkel\ 0881^ Sanders+ Friedman\ 0886# belong to the family of {sandy plastic

~ows|[ Synonymous terms used for these sandy typesinclude] "0# ~owing!grain layers\ "1# ~uidized ~owing!grain layer\ "2# inertia!~ow layer\ "3# avalanching ~ow"see Sanders + Friedman\ 0886#\ "4# traction carpet\ and"5# high!density turbidity current "see Shanmugam\0885a#[ All these sandy ~ows have one important prop!erty in common\ namely\ plastic rheology[ Therefore\ theuse of a general term {sandy debris ~ow| for all thesetypes may help minimize the terminology congestion inthe sedimentologic literature[ Also\ when we are unableto distinguish the speci_c type of a down!slope gravity~ow\ a more general term {sediment!gravity ~ow| is pre!ferred[


Fig[ 4[ Four di}erent de_nitions of turbidity currents based on "0# rheology of ~uids\ "1# sediment!support mechanism\ "2# driving force\ and "3#velocity:time factors[ Of these four types\ only the Newtonian and turbulent types are useful in interpreting the behavior of ~ow because evidencefor ~uid rheology and sediment!support mechanism is preserved in the deposit[ However\ evidence for driving force and waxing velocity is not alwayspreserved[

3[2[ Differing de_nitions of turbidity currents

In spite of the precise de_nition of turbidity currentsdiscussed above\ there are other de_nitions of turbiditycurrents with widely di}ering concepts[ I have selectedfour types based on four di}erent criteria "Fig[ 4#] "0#Newtonian ~ows based on rheology "Dott\ 0852#\ "1#turbulent ~ows based on sediment!support mechanism"Middleton + Hampton\ 0862#\ "2# high!density turbiditycurrents based on driving force "Postma et al[\ 0877#\ and"3# waxing ~ows based on velocity "Kneller\ 0884#[ Ofthese four types\ only the _rst two types are useful inrecognizing depositional processes because evidence forrheology and sediment!support mechanism is preservedin the rock record[

In Newtonian ~ows "i[e[\ turbidity currents#\ the depo!sition occurs through unhindered settling of individualgrains from suspension[ Hence\ normal grading\ indica!tive of Newtonian rheology and ~uid turbulence\ is acharacteristic feature of a turbidite[ However\ normalgrading is not unique to turbidites^ it has also beenobserved in dilute experimental debris ~ows as well "Marret al[\ 0886#[ Normally graded beds of debris ~ow origin

can be distinguished from normally graded beds of tur!bidity current origin by associated features[ For example\~oating granules and clasts in a normally graded sandunit are indicative of deposition through hindered settlingin a plastic debris ~ow rather than in a Newtonian tur!bidity current[ I will return to this point later[

{High!density turbidity currents| are de_ned based onthe driving force "Fig[ 4#[ For example\ the basal tractioncarpets "also known as inertia!~ow layer# in {high!densityturbidity currents| are driven by the overriding turbiditycurrents "Postma\ et al[\ 0877#[ In addition\ {high!densityturbidity currents| are de_ned based on grain size "Lowe\0871#\ on rapid deposition\ and on ~ow density "Kuenen\0849#[ Because of these conceptually di}ering ~ow types\there are no standard criteria to recognize deposits ofhigh!density turbidity currents[ This confusion has pavedthe way for interpreting deep!water massive sands ofdebris!~ow origin as high!density turbidites[ In fact\ theterm {high!density turbidite| is a misnomer because theterm {high density| should refer to the density of the ~ow\not the density of the deposit[

The concept of {high!density turbidity currents|\ basedon ~ow density with a range of 0[4Ð1[9 "Kuenen\ 0849#\


Fig[ 5[ "A# An experimental view of {high!density turbidity currents| by Postma et al[ "0877# who suggested that the basal high!concentration layer"labeled as sandy debris ~ow# was driven by the upper low!concentration layer "labeled as turbidity current#[ According to Postma et al[ "0877#\ bothupper and lower layers comprise the {high!density turbidity currents|[ I consider upper and lower layers as rheologically di}erent entities and thereforeseparate ~ow processes "see Shanmugam\ 0885a#[ "B# According to Postma et al[ "0877#\ lower and upper layers represent non!Newtonian andNewtonian rheology\ respectively[ "C# According to Postma et al[ "0877#\ lower and upper layers represent laminar and turbulent states\ respectively[The basal laminar layer "i[e[\ sandy debris ~ow# is variously termed as inertia!~ow layer\ traction carpet\ ~owing!grain layer etc[ by various authors"see Shanmugam\ 0885a#[ The basal layer with high sediment concentration promotes hindered settling\ and allows development of ~oating mudstoneclasts and quartz granules[ "D# Interpretation of Postma et al[ "0877#[ Because sediment!gravity ~ows are classi_ed on the basis of rheology andsediment!support mechanism "Lowe\ 0871#\ a single ~ow "i[e[\ high!density turbidity current# cannot be both Newtonian and non!Newtonian inrheology\ and laminar and turbulent in state at the same time[ This type represents gravity ~ow transformation of Fisher "0872#[ From Shanmugam"0886a#[

is a highly confusing one because the density may varydramatically through the ~ow[ A ~ow density of 1[9 is notunique to high!density turbidity currents because debris~ows also have a density of 1[9 "Hampton\ 0861#[ Atthese high ~ow densities\ turbulence would be dampedby high sediment concentration\ and ~ows would becomenon!turbulent "i[e[\ laminar#[ Without turbulence\ high!density ~ows cannot be turbidity currents "Shanmugam\0885a#[

The other problem is that a {high!density turbiditycurrent|\ de_ned on the basis of driving force\ is a density!strati_ed ~ow composed of a lower layer "i[e[\ high!con!centration\ plastic\ laminar# and an upper layer "i[e[\ low!concentration\ Newtonian\ turbulent#\ in which the basalhigh!concentration layer "i[e[\ traction carpet# cannot bea turbidity current because of its plastic rheology andlaminar ~ow state "Fig[ 5#[ The basal layer with highsediment concentration would severely hinder settling\and would freeze mudstone clasts and quartz granules in~oating positions[

Kneller "0884# observed that simple normally gradedbeds are rare in deep!water sequences\ and that mostdeep!water sequences with complications "e[g[\ massivesandstones\ disordered sequences\ abrupt grain!sizebreaks\ large!scale bedforms etc[# are di.cult to interpretas turbidites[ In alleviating this problem\ Kneller "0884#

has rede_ned turbidity currents using velocity "u#\ dis!tance "x#\ and time "t#\ and classi_ed turbidity currentsinto _ve types\ namely "0# depletive waning ~ow\ "1#uniform waning ~ow\ "2# depletive steady ~ow\ "3# deplet!ive waxing ~ow\ and "4# accumulative waning ~ow[ Thisclassi_cation allows room for interpreting deep!waterdeposits with any kind of grading "i[e[\ normal or inverse#as turbidites "Fig[ 6#[ The very foundation of the turbiditeparadigm\ based on the relationship between turbiditesand normal grading "Kuenen + Migliorini\ 0849^ Bouma\0851#\ has been undermined by the introduction of con!cepts relating massive sands "Harms + Fahnestock\ 0854#and inversely graded sands "Kneller\ 0884# to turbidites"Fig[ 6#[

Unlike the conventional de_nition of turbidity currentsbased on ~uid rheology and ~ow turbulence that takeinto consideration sediment concentration\ velocity\thickness\ and viscosity\ Kneller|s "0884# de_nition is pri!marily concerned with velocity[ The object of rede_ningturbidity currents using velocity alone serves no realscienti_c purpose^ although it does provide a psycho!logical solace in interpreting all deep!water sands as tur!bidites whether they show normal grading or not[ I wouldsuggest that rarity of normally graded beds in the rockrecord simply means that deposits of true turbidity cur!rents are rare in nature;


Fig[ 6[ Three publications showing how opinions on nature of grading in turbidites have changed through time[ Top] Bouma "0851# suggested normalgrading for turbidites[ Middle] Harms and Fahnestock "0854# proposed normal grading and massive "i[e[\ no grading# for turbidites[ Bottom] Kneller"0884# advocated normal grading\ massive "i[e[\ no grading#\ and inverse grading for turbidites[

3[3[ Inappropriate subaerial analogs for turbidity currents

A troubling practice is to compare subaqueous turbiditycurrents with subaerial river currents "Chikita\ 0878#[This comparison is ill!founded for many reasons "Table0#[ River currents and turbidity currents are fun!damentally di}erent\ although both are turbulent in state"Shanmugam\ 0886a#[ River currents are low in sus!pended sediment "0Ð4) by volume^ Galay\ 0876#\whereas turbidity currents "i[e[\ low!density turbidity cur!rents# are relatively high in suspended sediment "0Ð12)by volume^ Middleton\ 0856\ 0882#\ although both cur!rents are considered to be Newtonian in rheology "Fig[ 3#[River currents are ~uid!gravity ~ows\ whereas turbiditycurrents are sediment!gravity ~ows "Middleton\ 0882#[ Inriver currents\ sand and gravel fractions are transportedprimarily by bed load "traction# mechanism\ and there!

Table 0Comparison of subaerial river currents and subaqueous turbidity currents[ Partly based on Shanmugam "0886a#

Features River currents Turbidity currents

Ambient ~uid Air WaterRheology of ~uid Newtonian NewtonianType of gravity ~ow Fluid gravity ~ow Sediment gravity ~owNature of ~ow Uniform\ steady\ and continuous Non!uniform\ unsteady\ and episodicSediment concentration Low "0Ð4 vol[)# High "0Ð12 vol[)#Dominant transport of sand and gravel Bed load Suspended loadDominant structures Cross bedding Normally graded bedding

fore river deposits are characterized by dune bedformswith cross bedding[ In contrast\ sands in true turbiditycurrents "i[e[\ low!density turbidity currents# are trans!ported by suspended load\ and thus sandy turbidites showa general lack of cross bedding and show a characteristicnormal grading[

Bouma and Coleman "0874# interpreted the deep!waterAnnot Sandstone\ exposed in Peira Cava area in SEFrance\ as lateral accretionary channel!_ll turbiditesusing ~uvial point!bar analogy[ They used the presenceof pebble nests\ foreset bedding\ and paleocurrent direc!tions in support of their interpretations[ However\ thisanaology is inappropriate for several reasons[ First\ theAnnot Sandstone example used in the study does notshow channel geometry "e[g[\ Bouma + Coleman\ 0874\their _g[ 2#\ but does show a sheet geometry\ which isan unlikely geometry of lateral!accretion deposits by a


Fig[ 7[ Comparison of size!velocity diagram for bed forms "structures# developed in ~ume experiments at a ~ow depth of 19 cm "compiled from manysources\ see Southard "0864## with the _ve internal divisions "A\ B\ C\ D\ and E# of the Bouma "0851# Sequence[ Bouma divisions A\ B\ C\ and Dare labeled in the size!velocity diagram for _ne!grained sand for discussion purposes[ Note that dunes and in!phase waves "antidunes# observed in~ume experiments are absent in the Bouma Sequence[ Also note that the basal normally graded division of the Bouma Sequence is absent in ~umestrctures[ Published size!velocity diagram of experimental structures by Southard "0864# is ~ipped vertically in order to make an easy comparisonwith the Bouma Sequence[

meandering channel[ Second\ the logged sequences of theAnnot Sandstone in Peira Cava do not contain sedi!mentary facies in support of the lateral accretion model"Oakeshott\ 0878#[ Third\ the pebble nests in the AnnotSandstone are analogous to slurried beds\ and slurriedbeds were interpreted to be deposits of debris ~ows"Mutti\ Nilsen + Ricci Lucchi\ 0867#[ In addition toslurried beds\ the Annot Sandstone exhibits inverse grad!ing at the base and contains armoured mud balls "Pick!ering + Hilton\ 0887^ Stanley\ Palmer + Dill\ 0867#[ Iwould suggest that these features are products of debris~ows\ and plastic debris ~ows are not a viable mechanismto explain lateral accretion deposits in a meanderingchannel[ Also\ the origin of meandering channels byunsteady turbidity currents in deep!marine environmentsis still an unresolved issue[

Perhaps\ the most problematic issue is the use of the_ve alluvial channel bed forms "i[e[\ plane bed\ ripples\dunes\ upper ~ow regime plane bed\ and antidunes#observed in ~ume experiments "Simons\ Richardson +Nordin\ 0854^ Southard\ 0864# as the analog for the _vedivisions of the Bouma "0851# Sequence "see Harms +Fahnestock\ 0854^ Walker\ 0854#[ Although this com!parison is deeply embedded in our psyche "Fig[ 7#\ it isnot founded on sound ~uid dynamic principles[

Simons et al[ "0854# cautioned that sedimentary struc!tures observed in their ~ume experiments are meaningfulonly for structures developed in subaerial alluvial chan!nels[ The obvious implication is that these experimentalalluvial structures are not analogous to turbidite struc!tures formed under subaqueous environments[

Simons et al[ "0854# conducted ~ume experimentsunder equilibrium ~ow conditions[ However\ in mostnatural ~ows\ changes in bed con_gurations tend to lagbehind changes in ~ow conditions\ and there have beenalmost no ~ume experiments on disequilibrium bed con!_gurations "Southard 0864#[ Natural turbidity currentsare waning ~ows\ and waning ~ows may never attainequilibrium "see Allen\ 0862#[

On the use of experimental structures of Simons et al["0854# as analog for turbidite structures\ Walker "0854#cautioned\ {{[ [ [ the ~ume experiments were conductedunder conditions of non!deposition\ whereas many of thesedimentary structures of turbidites are formed underconditions of net deposition[||

Dunes are an integral part of bed forms produced in~ume experiments of alluvial channels "Simons et al[\0854#\ whereas cross beds "i[e[\ internal structures of dunebed forms# are absent in the Bouma Sequence "Fig[ 7#[In fact\ all structures observed in ~ume experiments were


formed under traction or bed load "Simons et al[\ 0854#[The origin of traction structures requires establishmentof hydrodynamic equilibrium[ The duration required forestablishing hydrodynamic equilibrium is greater thanthe time required for sedimentation "Allen\ 0862#[ There!fore\ traction structures formed in ~ume experiments arenot appropriate analogs for interpreting structures for!med by natural turbidity currents[ It is worth remem!bering that Kuenen "0853# would use the presence ofdune structures in deep!water sandy sequences as evi!dence against turbidite deposition[

The very last stages of sand transport by {dilute tail| endof turbidity currents may form thin divisions of parallellamination by reworking "Kuenen\ 0842\ 0853#[However\ the {dilute tail| concept can be invoked only ifthere is evidence for turbidite deposition\ independent ofparallel lamination[ This evidence must constitute] "0#the presence of a normally graded division beneath thedivision of parallel lamination\ "1# the presence of a nor!mally graded division that is thicker than the overlyingdivision of parallel lamination\ "2# the presence of a nor!mally graded division without associated inverse grading\and "3# the presence of a normally graded division with!out ~oating mudstone clasts and ~oating quartz granules[In the absence of an underlying normally graded division\the origin of parallel lamination by {dilute tail| end ofturbidity currents cannot be invoked because the {dilutetail| end of waning turbidity currents cannot attain equi!librium[

The routine interpretation of deep!water sands withthick divisions of {parallel lamination| as upper ~owregime ~at beds of turbidity currents is not justi_edbecause thick upper ~at beds have never been generatedby experimental turbidity currents[ On the other hand\experimental studies have shown that some horizontallayers formed by sandy debris ~ows may mimic {parallellamination|[ Also\ the development of pervasive lami!nation has been ascribed to sediment shear during freez!ing of mass ~ows "Stau}er\ 0856#[ Furthermore\ deepbottom currents are traction currents and are quite cap!able of generating parallel lamination[ In other words\there is no reason to assume that all laminated beds are{turbidites| "Murphy + Schlanger\ 0851#[

Kuenen "0853# stated\ {{[ [ [ a turbidity current musthave carried its load of grains in suspension almost up tothe point at which each particle comes to rest||[ For thisreason\ normal grading is typical of turbidite beds\ but isabsent in experimental structures of alluvial channels"Fig[ 7#[

To date\ no one has ever generated the completeBouma Sequence\ with all its _ve divisions\ by turbiditycurrents with Newtonian rheology and turbulent state in~ume experiments[ There are no size!velocity type diag!rams for turbidity currents[ Clearly\ there is a conceptualdisconnect when we try to explain the origin of turbiditesdeposited from suspension using the origin of exper!

imental structures formed from traction[ Therefore\ thecurrent hydrodynamic interpretation of the BoumaSequence is tenuous[ New experiments are needed inestablishing the true relationship between sequence ofstructures\ if any\ in turbidites and their realtionship todeposition from turbidity currents[

A common perception is that high!density turbiditycurrents in subaqueous environments are analogous tohyperconcentrated ~ows in subaerial environments "Fig[8#[ According to Pierson and Costa "0876#\ hyp!erconcentrated ~ows are plastic ~ows\ and therefore\{high!density turbidity currents| cannot be true turbiditycurrents[ In China "Qian\ Yang\ Zhao\ Cheng\ Zhang\ +Xu\ 0879#\ the term {hyperconcentrated ~ow| is used fortwo distinctly di}erent ~ow types] "0# Newtonian ~uidscharacterized by low sediment concentration and tur!bulent state in which coarse and _ne particles settle sep!arately\ and "1# Bingham "i[e[\ non!Newtonian# ~uidscharacterized by high sediment concentration and lami!nar state in which coarse and _ne particles are depositedtogether "i[e[\ freezing#[

Analogous to the application of the term {hyp!erconcentrated ~ow| for both turbulent and laminar ~owsin subaerial environments "Qian et al[ 0879#\ the term{high!density turbidity current| is applied to both tur!bulent and laminar ~ows in subaqueous environments"Postma et al[\ 0877#[ High!density turbidity currents arecommonly perceived to occupy an intermediate positionbetween low!density turbidity currents and debris ~ows"Fig[ 8#[ Although the introduction of the {hypercon!centrated stream ~ow| concept for conditions inter!mediate between {normal stream ~ow| and {debris ~ow|in subaerial environments appears to have resolved theproblem of intermediate ~ows "Beverage + Culbertson\0853#\ the boundaries between these ~ow types based onsediment concentration vary with grain size and com!position "Pierson + Costa\ 0876#[ The other problem isthat both hyperconcentrated ~ows and debris ~ows areconsidered to be non!Newtonian ~uids that exhibit plas!tic behavior "Fig[ 8#[ In short\ the use of subaerial rivercurrents and hyperconcentrated ~ows as analogs forsubaqueous turbidity currents\ in my opinion\ is notappropriate[

3[4[ Flow transformation in sediment!gravity ~ows

Based on theoretical hydrodynamic considerations\Kuenen "0849# proposed downslope transformations ofslumping to mud ~ow\ and subsequently others haveproposed transformations of slumping and debris ~owsto turbidity currents "Dott\ 0852^ Hampton\ 0861#[ Thetransformation of one type of ~ow "e[g[\ laminar debris~ow# to another "e[g[\ turbulent turbidity current# duringtransport is perhaps the most important and the leastunderstood phenomenon in process sedimentology[ Anunderstanding of ~ow transformation is important


Fig[ 8[ Schematic diagram showing inconsistencies when comparing subaerial {hyperconcentrated ~ow| with subaqueous {high!density turbiditycurrent|[ See text for details[

because whether a ~ow had transported sediment indebris!~ow mode or turbidity!current mode is critical indeveloping a geologic model[ For example\ Newtonianturbidity currents are more likely to spread laterally thanplastic debris ~ows[ Also\ deposition of sediment by set!tling from turbidity currents vs by freezing from debris~ows will make a di}erence in sandbody geometry[ How!ever\ there are no established criteria for recognizingtransport mechanisms in the depositional record becauseof ~ow transformations "Dott\ 0852^ Walton\ 0856^ Mid!dleton + Hampton\ 0862^ Carter\ 0864^ Stanley et al[\0867^ Lowe\ 0871^ Postma\ 0875^ Middleton\ 0882^ Shan!mugam\ 0885a#[ For this reason\ process terms used inthis review refer only to depositional mechanisms\ nottransport mechanisms[

Four types of transformations have been proposed forsediment!gravity ~ows by Fisher "0872#[ They include"0# body transformation\ "1# gravity transformation\ "2#surface transformation\ and "3# elutriation trans!formation "Fig[ 09#[ Experimental studies of Postma etal[ "0877# have shown that turbidity currents can developbasal laminar layers "i[e[\ sandy debris ~ows# by gravity~ow transformation "Fig[ 5#[ Postma et al[ "0877# calledsuch ~ows as {high!density turbidity currents|[ Exper!imental studies have also shown that plastic debris ~owscan be diluted to develop Newtonian turbidity currents"Hampton\ 0861^ Marr et al[\ 0886#[ If a laminar debris~ow generates an upper turbulent cloud "i[e[\ turbiditycurrent# due to surface ~ow transformation "Fig[ 00#\then we should call it a {low!density debris ~ow| if weapply the reasoning of Postma et al[ "0877# for high!density turbidity current "Fig[ 5#[ This is because theseturbidity currents are derived from and initially drivenby underlying debris ~ows[ Although these turbidity cur!

Fig[ 09[ Four types of ~ow transformations in sediment!gravity ~ows"modi_ed after Fisher\ 0872#[

rents are generated by dilution of debris ~ows\ thesecurrents still possess distinct Newtonian rheology andturbulent state that are characteristics of turbiditycurrents[ Therefore\ I discourage any classi_cation ofsediment!gravity ~ows based on driving forces[

Phillips and Davies "0880# noted\ {{[ [ [ although a ~ow


Fig[ 00[ Problems in classifying sediment!gravity ~ows based on driving forces[ Top] If a turbidity current generates a basal high!concentrationlaminar layer due to gravity ~ow transformation\ Postma et al[ "0877# would call it a {high!density turbidity current|[ This is because the basal high!concentration layer is derived from and driven by over!riding turbidity currents[ Open arrow shows direction of transport[ Bottom] If a laminardebris ~ow generates an upper turbulent cloud "i[e[\ turbidity current# due to surface ~ow transformation through dilution "e[g[\ Hampton\ 0861#\we should call it a {low!density debris ~ow| if we follow the reasoning of Postma et al[ "0877# for high!density turbidity current[ These weak turbiditycurrents are not capable of transporting sand and gravel in suspension[ Open arrow shows direction of transport[

may start as a viscous plastic material it may subsequentlydevelop grain!dispersive characteristics[ Then\ as shearrates are reduced\ for example\ by a reduction in bedslope or by jamming of coarse grains in the channel\ the~ow may once again exhibit plastic!viscoplasticbehavior||[ In other words\ a debris ~ow may transforminto a grain ~ow\ and then back to a debris ~ow again[Similarly\ Middleton "0869# has suggested the trans!formation of a grain ~ow "laminar state# to a turbiditycurrent "turbulent state# and returning to a grain ~ow"laminar state# during the last stages of deposition[

In discussing the physics of debris ~ows\ Iverson "0886#stated\ {{When mass movement occurs\ the sediment!water mixtures transform to a ~owing\ liquid!like state\but eventually they transform back to nearly rigiddeposits||[ In other words\ although these trans!formations do occur during transport\ evidence for ~owtransformations cannot be inferred from the _nal deposit[

The challenge in interpreting the depositional recordhas always been how to distinguish ~ows that underwent~ow transformation from ~ows that did not[ Many of ususe this universal constraint as a license to assume thatall deep!water sands must have been transported by tur!bidity currents and subsequently underwent late!stageplastic deformation to resemble debris!~ow deposits[This false assumption is one of the reasons why the tur!bidite facies models have been reigning over the debris~ow facies models during the past 49 years[

3[5[ Theoretical sandy debris ~ows

The concept of sandy debris ~ows was _rst introducedby Hampton "0864#[ I have expanded that concept toinclude the following speci_c parameters "Fig[ 3#] "0#plastic rheology\ "1# multiple sediment!support mech!anisms "cohesive strength\ frictional strength and buoy!ancy#\ "2# mass transport mode\ "3# a minimum of 14Ð29) sand and gravel\ "4# 14Ð84) sediment "gravel\ sandand mud# concentration by volume\ and "5# variable claycontent "as low as 9[4) by weight#[ I would suggest thatrheology is more important than gran!size distribution incontrolling sandy debris ~ows[ I would also suggest thatsandy debris ~ows can develop in slurries of any grainsize "very _ne sand to gravel#\ any sorting "poor to well#\any clay content "low to high#\ and any modality "unim!odal and bimodal#[ Sandy debris ~ows have been dis!cussed previously in some details "Shanmugam\ 0885a\0886a#[

Theoretically\ grain ~ows "i[e[\ cohesionless debris~ows# and muddy debris ~ows "i[e[\ cohesive debris ~ows#can be considered to be two end members of plastic ~ows"Fig[ 01#[ Sandy debris ~ows are considered to representan intermediate position between grain ~ows with fric!tional strength and muddy debris ~ows with cohesivestrength "Shanmugam\ 0886a#[ Therefore\ multiple sedi!ment support mechanisms\ such as\ cohesive strength\frictional strength and buoyancy are proposed for sandy


Fig[ 01[ Theoretical vs natural debris ~ows[ Theoretically\ grain ~ows "i[e[\ cohesionless debris ~ows# and debris ~ows "i[e[\ cohesive debris ~ows# canbe considered to be two end members of rheological {debris ~ows| "Lowe\ 0868#[ Following Lowe "0868#\ the rheologic term {plastic| is used for bothgrain ~ows " frictional strength# and debris ~ows "cohesive strength#[ Sandy debris ~ows are considered to represent an intermediate position betweenend!member types\ and therefore\ multiple sediment support mechanisms are proposed for sandy debris ~ows[ An advantage of this concept is thatit requires neither the steep slopes required for grain ~ows nor the high matrix content necessary for cohesive debris ~ows[ From Shanmugam "0886a#[

debris ~ows "Fig[ 3#[ An advantage of this concept is thatit requires neither the steep slopes necessary for grain~ows nor the high matrix content necessary for cohesivedebris ~ows[

3[6[ Experimental sandy debris ~ows

One of the main criticisms that has been leveled at theconcept of sandy debris ~ows is the erroneous notion thatall debris ~ows must have a high clay content in orderto provide the necessary strength "e[g[\ D|Agostino +Jordan\ 0886#[ Although Hampton "0864# has noted thatas little as 1) clay is su.cient to provide the strengthfor sandy debris ~ows\ some members of the geologiccommunity "e[g[\ D|Agostino + Jordan\ 0886# are stilltroubled by the concept of sandy debris ~ows with lowclay content[ Costa and Williams "0873# also showed anumber of mud!poor debris ~ows in which clasts arelubricated by a mud slurry\ but mud constitutes less than0 or 1) of the debris ~ow[

In verifying the concept of sandy debris ~ows with lowclay content\ experiments were conducted on subaqueoussandy debris ~ows at St[ Anthony Falls Laboratory ofthe University of Minnesota "Marr et al[\ 0886#[ Theexperimental ~ume used was 09m in length\ 29 cm inwidth\ and 79 cm in depth "Fig[ 02#[ The ~ume was _ttedwith three di}erent slopes] 3[5\ 0[0\ and 9> in order toobserve changes in deposition at points of slope change[Sediment slurries were composed of silica sand "019mmsize#\ clay "bentonite or kaolinite#\ coal slag "same bulk

density as silica sand] 1[5 g:cm2#\ and water[ Coal slag of499mm size was used as tracer material[ Sandy debris~ows were generated with bentonite clay content as lowas 9[4) by weight or with kaolinite clay 4) by weight[Sandy debris ~ows were also generated using medium!grained sand "299mm size# with bentonite clay content aslow as 0[4) by weight or kaolinite clay 4) by weight[

The following general observations can be maderegarding sandy debris ~ows based on our experimentalstudies]

0[ Sandy debris ~ows are a viable mechanism for trans!porting and depositing sand in subaqueous environ!ments[

1[ Sandy debris ~ows can travel long distances on gentleslopes "less than 0>#[

2[ Contrary to popular belief\ sandy debris ~ows donot require high clay content[ As low as 9[4) claycontent is su.cient to generate sandy debris ~ows[However\ without that amount of clay\ debris ~owswill not develop[ In the absence of clay\ the sand!water slurry either becomes a short!lived grain ~owor a short!lived turbidity current[

3[ Sandy debris ~ows were developed from slurries ofboth bimodal and unimodal grain!size distribution[

4[ The ratio of water to clay and types of clay determinethe ~ow behavior[ For example\ by maintaining aconstant amount of kaolinite at 04) by weight\ andby increasing the water content\ three di}erent typesof sandy debris ~ows "i[e[\ strong\ moderate\ and


Fig[ 02[ Dimensions of the ~ume used in sandy debris ~ow experiments described in this paper[ From Marr et al[ "0886#[

weak#\ re~ecting a decrease in ~uid strength\ are gen!erated at 14\ 29\ and 39) water by weight\ respec!tively "Fig[ 03#[ The signi_cance of this observationis that the change of water content alone can make adi}erence in the ~ow behavior[ More importantly\the amount of clay in the deposit is not always an

Fig[ 03[ Changes in ~ow behavior of sandy debris ~ows with changesin water and kaolinite clay[ Note that with 39) water\ debris ~ow typeschange from weak through moderate to strong at kaolinite content of04\ 14\ and 24)\ respectively[ At 04) kaolinite\ debris ~ow changesfrom weak through moderate to strong types with 39\ 29\ and 14)water\ respectively[ In other words\ increasing clay content and decreas!ing water content result in stronger debris ~ows[ From Marr et al["0886#[

useful criterion in interpreting the nature of ~ow[Primary sedimentary features are more reliable ininterpreting ~ow behavior than clay content[Deposits of sandy debris ~ows with low clay content"e[g[\ 9[4)# are obvious candidates for mis!interpretation as the deposits of other processes\ suchas {high!density| turbidity currents and grain ~ows[

5[ Subaqueous debris ~ows tend to develop hydro!planing\ whereas subaerial debris ~ows do not"Mohrig et al[\ 0887#[ Experimental studies of suba!queous debris ~ows have shown that hydroplaningcan dramatically reduce the bed drag\ and thusincrease head velocity "Mohrig et al[\ 0887#[ Thisexplains why subaqueous debris ~ows can travel fas!ter and farther on gentle slopes than subaerial debris~ows[

6[ In subaqueous debris ~ows with hydroplaning\ ero!sion does not occur "Mohrig et al[\ 0887#[

7[ Water!escape structures "dishes and pillars# havebeen observed in experimental sandy debris ~ows[Dish structures and pillars are commonly ascribedto liquefaction and ~uidization "Lowe\ 0864#[ Lowe"0864# suggested that dish structures form throughthe following steps] "0# when vertically escapingwater meets an impermeable barrier the water is for!ced to move laterally until discontinuities form\ "1#at discontinuities the water resumes its vertical move!ment resulting in the evacuation of ~uid under theimpermeable barrier\ "2# the evacuation of waterresults in the formation of cavity under the imper!meable barrier\ and _nally "3# the collapse of thecavity forms the dish structures[ Lowe "0864# explai!


Fig[ 04[ Stages of development of water!escape structures in sandy debris ~ows] "0# hydroplaning\ "1# water entrapment in cavities\ and "2# waterescape[ Settling of debris!~ow layer squeezes the water in cavities to escape upward\ resulting in sand volcanoes\ dish structures\ and vertical pipes[This diagram is based on direct observations of experiments as well as observations made on videotapes of experiments[

ned that pillars form when horizontal ~ow of wateris converted to vertical ~ow[

The dish structures in experimental sandy debris~ows form in three stages\ namely\ "0# hydroplaning\"1# water entrapment\ and "2# water escape "Fig[04#[ During the hydroplaning stage\ water penetratesunderneath the plastic ~ow layer "Fig[ 04\ Stage 0#[When the deposit begins to settle\ water gets trappedin cavities underneath the bed "Fig 05A^ Fig[ 04\Stage 1#[ Finally\ further settling of sediment causesthe trapped water to escape by bursting open the topof the cavity\ resulting in a sand volcano[ A fullydeveloped volcano would form a dish!shaped basalsurface "Fig[ 04\ Stage 2#\ which would eventuallymimic dish structures along the bedding surface inthe rock record[ Water escape also results in verticalpipes or pillars "Fig[ 06B#[

Water!escape structures in deep!water sands werepreviously used as evidence for deposition from liqu!e_ed ~ows and high!density turbidity currents"Lowe\ 0871#[ Our experiments suggest that water!escape structures are quite common in subaqueoussandy debris ~ows with hydroplaning[ Perhaps\ thepresence of water!escape structures in sandy debris~ows may be used as evidence for inferring hyd!roplaning[

8[ Inverse grading is common in sandy debris ~ows"Fig[ 05B#[

09[ Normal grading also develops in weak debris ~ows"Fig[ 06A#[ Settling of coarser grains occurs fromsuspension through hindered settling after the ~owstopped[ This settling of grains from a non!turbulent"i[e[\ laminar# ~ow after the ~ow had halted is di}er!

ent from settling of grains that occurs from a tur!bulent turbidity current during transport[

A di}erent origin for the development of normalgrading in muddy debris ~ows has been proposed byVallance and Scott "0886# who stated\ {{if normallysegregated ~ow stops rapidly enough\ the resultingdeposit will be normally graded[|| In short\ debris~ows can develop inverse grading\ normal grading\or no grading\ whereas turbidity currents can developonly normal grading[

Sandy debris ~ows with normal grading could bemisinterpreted as turbidites in the rock record "Fig[06B#[ Normally graded sandy debris ~ows can bedistinguished from normally graded sandy turbiditesby the associated features[ For example\ ~oating cla!sts and granules due to hindered settling are commonin {normally graded| debris ~ows[ In turbidites\ how!ever\ ~oating clasts and granules are not likely to bepresent because of unhindered settling[

In experiments using 299mm size silica sand and 4wt) kaolinite\ sandy debris ~ows developed not onlya normal grading\ but also a relatively clean basalsand layer[ The origin of this clean basal sand layeris speculated to be by sudden settling of sand grainscoupled with upward migration of mud[ This hasimportant implications for developing alternativedeep!water depositional models because the con!ventional wisdom dictates that only turbidites formgood!quality reservoirs[ Our experiments suggestthat sandy debris ~ows are capable of forming clean\mud poor sands[

00[ Massive sand emplaced by sandy debris ~ows exhi!bits a random distribution of coal slag throughout


Fig[ 05[ "A# Side view of ~ume tank showing sandy debris ~ows with water entrapment "arrow# beneath a debris!~ow layer "i[e[\ Stage 1 in Fig[ 04#[Trapped water escapes when the sandy debris ~ow layer begins to settle toward the ~ume ~oor\ causing sand volcanoes[ Horizontal distance between3[9 and 3[0 markers is 09 cm[ Flow direction from right to left[ "B# Side view of ~ume tank showing sandy debris ~ows with a middle layer of coalslag "arrow# in a sandy unit "white#[ The sandy unit is composed of a basal inversely graded layer^ an upper normally graded layer\ and a middle coalslag layer[ Horizontal distance between 3[7 and 3[8 markers is 09 cm[ Flow direction from right to left[

the bed "Fig[ 07A#\ which is analogous to ~oatinggranules in sandstone[

01[ Internal layers in sandy debris ~ows develop becauseof post!depositional movement along failure planes"or secondary glide planes# during remobilization of~ows "Fig[ 07B#[ These layers could be misidenti_edas parallel lamination in the rock record\ resultingin an erroneous interpretation of the depositionalprocess[

02[ Imbricate slices can develop in sandy debris ~ows[When the front of a ~ow freezes\ the body of the ~owbreaks away from the front end and overrides thefront as successive thrust slices "Fig[ 07B#[ Imbricateslices suggest compression[ Large scale com!pressional ridges have been reported from a modernsubmarine {~ow slide| in a fjord in British Columbia"Prior\ Bornhold + Johns\ 0873#[ Imbricate slices"duplex!like structures# also have been reported fromthe subaerial Blackhawk landslide "Shreve\ 0857#\and from the Pennsylvanian ~ysch sequences in theOuachita Mountains in Arkansas "ShanmugamMoiola + Sales\ 0877a#[ Duplex structures are con!

ventionally associated with tectonic activity\ andtherefore\ it is important to know that duplex!likestructures can also be formed by remobilization ofsandy debris ~ows unrelated to tectonic activity[

03[ The frontal part "snout# of sandy debris ~ows com!monly comes to a sudden stop due to freezing[ Snoutsare characterized by irregular and:or sharp frontaledges "Fig[ 08A#[

04[ During remobilization\ frontal parts of sandy debris~ows detach themselves from the main body andstart to move ahead of the main body as isolatedblocks "Fig[ 08B#[ Such isolated blocks are evidencefor tensional movement[ Large bodies of isolatedmuddy debris ~ows and slumps have been reportedfrom modern oceans "Embley\ 0865\ 0879^ Embley+ Jacobi\ 0866#[ Recognition of similar isolated bod!ies of sandy debris ~ows in the subsurface has impor!tant implications for hydrocarbon exploration[

A summary of all the features observed in the ~umeexperiments of sandy debris ~ows "Fig[ 19# suggest thatmany of these features can easily be mistaken for other


Fig[ 06[ "A# Side view of ~ume tank showing sandy debris ~ows with a high concentration of coal slag forming a distinct basal black layer "arrow#[This basal layer formed through hindered settling after the ~ow had stopped[ This could be mistaken for {normal grading| deposition from turbiditycurrents in the rock record[ Normal grading has been reported from muddy debris ~ows in the rock record "Vallance and Scott\ 0886#[ Horizontaldistance between 4[7 and 4[8 markers is 09 cm[ Flow direction from right to left[ Note smooth upper surface[ "B# Side view of ~ume tank showingsandy debris ~ows with a moderate concentration of coal slags forming a faint basal black layer[ Note that the amount of coal slag gradually decreasesupward\ resembling {normal grading|[ In comparison to the above example "A#\ this example suggests a stronger ~ow that resulted in a severelyhindered settling[ Vertical pipes "arrow# were created by the escape of water[ Width of photo is approximately 09 cm[ Flow direction from right toleft[

depositional processes "e[g[\ turbidity currents\ lique_edand ~uidized ~ows#\ and for tectonic activity "duplexstructures#[ There are no vertical facies models fordeposits of sandy debris ~ows[

3[7[ Bottom currents

In large modern ocean basins\ such as the Atlantic\thermohaline!induced geostrophic bottom currentswithin the deep and bottom water masses commonly

~ow approximately parallel to bathymetric contours "i[e[\along slope\ Fig[ 10# and are generally referred to as{contour currents| "Heezen et al[\ 0855^ Ewing\ Ettreim\Ewing\ + Pichon\ 0860^ Flood + Hollister\ 0863#[However\ because not all types of bottom currents followregional bathymetric contours\ I prefer that the term{contour current| be applied only to currents ~owing par!allel to bathymetric contours\ and other currents betermed {bottom currents| "Shanmugam et al[\ 0882a\0882b\ 0884c#[ For example\ wind!driven surface currents


Fig[ 07[ "A# Side view of ~ume tank showing sandy debris ~ows with random distribution of coal slag "black grains# in massive sand[ Horizontaldistance between 3[9 and 3[0 markers is 09 cm[ Flow direction from right to left[ "B# Side view of ~ume tank showing sandy debris ~ows with imbricateslices "inclined arrow#[ Imbricate slices develop in sandy debris ~ows when the front of a ~ow freezes\ the body of the ~ow breaks and thrusts overthe slice in the front due to compression[ Similar features "duplex!like structures# have been reported from the rock record and have been ascribedto synsedimentary slumping processes "Shanmugam et al[\ 0877#[ However\ duplex structures are commonly associated with tectonic activity[ Notenearly horizontal or gently dipping internal layers "horizontal arrow#[ These layers are caused by post!depositional movement along failure planes"or secondary glide planes# during remobilization of ~ows[ These layers could be misidenti_ed as parallel lamination in the rock record\ which mayresult in erroneous interpretations of depositional processes[ Horizontal distance between 3[3 and 3[2 markers is 09 cm[ Flow direction from right toleft[


Fig[ 08[ "A# Side view of ~ume tank showing sandy debris ~ows with a sharp and irregular snout "arrow#[ Sharp and irregular snout is due to freezingof the ~ow[ Random distribution of coal slags is due to freezing of the ~ow with strength[ Horizontal distance between 4[7 and 4[8 markers is 09 cm[Flow direction from right to left[ "B# Map view of experimental sandy debris ~ows showing isolated blocks of sand bodies "arrow#[ These bodiesslowly get detached from the main body by tension[ Some detachments may be explained by hydroplaning and related faster moving head withrespect to the body[ Width of photo is approximately 09 cm[ Flow direction from right to left[


Fig[ 19[ A summary of features observed in experimental sandy debris ~ows[

may ~ow in a circular motion and form eddies that mayreach the deep!sea ~oor\ such as the Loop Current in theGulf of Mexico "Pequegnat\ 0861^ Bouma\ 0861#\ and theGulf Stream in the North Atlantic[ Local bottom currentsthat move up and down slope can be generated by tidesand internal waves^ especially in submarine canyons"Bouma + Hollister\ 0862^ Shepard\ Dill + Von Rad\0858#[ These currents are quite capable of erosion\ trans!portation\ and redeposition of _ne to coarse sand in thedeep sea[

Bottom currents] "0# are generally persistent for longtime intervals and can develop equilibrium conditions^ "1#transport sand primarily by traction "bedload movement!sliding\ rolling\ and saltation of Allen "0871##^ "2# aresometimes free of sediment\ and for this reason\ are

termed {clear water currents| "Bouma + Hollister\ 0862#^"3# entrain and transport passive sediment particles"Lowe\ 0868#^ "4# are driven by thermohaline\ wind\ wave\or tidal forces^ and "5# commonly ~ow parallel to theregional slope\ but can also ~ow in circular motions"gyres# unrelated to the slope "Pequegnat\ 0861#[ Thesecharacteristics clearly discriminate deep!sea bottom cur!rents from turbidity currents[ Bottom currents operateparallel to slope in most deep!water settings inde!pendently of down!slope turbidity currents\ debris ~ows\slumps\ etc[ As a result\ sands introduced into the basinepisodically by down!slope gravity processes would beconstantly reworked by bottom currents[ This interplayof processes would result in a vertical sequence not unlikethe {Bouma Sequence| "Shanmugam\ 0886a#[


Fig[ 10[ A schematic diagram showing gravity!driven downslope turbidity currents\ and parallel!to!slope bottom currents "also known as contourcurrents#[ From Shanmugam et al[ "0882a#[

Deposits of {contour currents| "i[e[\ bottom currents#have been termed {contourites| "Hollister\ 0856#[ Twodistinct types of contourites\ namely {muddy contourites|and {sandy contourites|\ have been recognized "Stow +Lovell\ 0868^ Stow + Holbrook\ 0873#[ Although criteriahave been proposed to distinguish muddy from sandycontourites "Stow + Lovell\ 0868^ Stow\ Faugeres\ Viana\+ Gonthier\ 0887#\ the real distinction between the twotypes in terms of sand content has not been established[There exists a continuum of facies between muddy andsandy types\ and the sand percentage that demarcates themuddy type from the sandy type has not been de_ned[ Infact\ the Faro Drift area in the Gulf of Cadiz\ which hasbeen used as the type area for the general model of bothmuddy and sandy contourites "Stow et al[\ 0887#\ con!tains only 4) sand "Gonthier\ Faugeres + Stow\ 0873#[I would set a lower limit of 14) sand for sandy contour!ites[ I prefer the general term {bottom!current!reworkedsands| to {sandy contourite| irrespective of the sandcontent\ so long as evidence for reworking of sands canbe established[

Contour currents have been shown to be complex andcan form strong circular eddies causing current reversalsand generate {abyssal storms| "Hollister + McCave\0873#[ For these reasons\ the use of paleocurrent direc!tions to recognize bottom!current deposits "Lovell +Stow\ 0870# under the assumption that all bottom cur!

rents follow regional bathymetric contours may be tenuous[Bottom!current!reworked sands can be recognized

using primary physical sedimentary structures "Hubert\0853^ Hollister\ 0856^ Hollister + Heezen\ 0861^ Bouma+ Hollister\ 0862^ Unrug\ 0866^ Stow + Lovell\ 0868^Lovell + Stow\ 0870^ Shanmugam et al[\ 0882a^ + Stowet al[\ 0887#[ Traction structures are considered to bethe only reliable criteria for recognizing bottom!currentreworked sands "Shanmugam et al[\ 0882a\ 0882b#[

I do not advocate any standard vertical facies modelfor bottom!current reworked sands\ however\ I do sug!gest that the following criteria may be useful in reco!gnizing bottom!current reworked sand in core andoutcrop of deep!water strata "Fig[ 11#]

0[ Predominantly _ne!grained sand and silt[1[ Thin!bedded to laminated sand "usually less than

4 cm# in deep!water mud[2[ Rhythmic occurrence of sand and mud layers[3[ Numerous sand layers "49 or more per 0 meter of

core#[4[ Sharp "non!erosional# upper contacts and sharp to

gradational bottom contacts[0

5[ Internal erosional surfaces[0

0 Diagnostic criteria[


Fig[ 11[ Suggested traction structures for recognizing deep!marine bottom!current reworked sands[ From Shanmugam et al[ "0882a#[

6[ Well!sorted sand and low depositional matrix "cleansand#[

7[ Inverse size grading "coarsening upward# at variousscales[0

8[ Horizontal lamination and low!angle crosslamination[0

09[ Cross!bedding[ Although Mutti "0866# advocatedthe origin of cross!bedding in deep!sea channel


mouth deposits due to by!passing of turbiditycurrents\ steady and equlibrium ~ow conditionsrequired for the formation of cross!bedding aredi.cult to envision in episodic turbidity currentevents at channel mouths[0

00[ Lenticular bedding:starved ripples at the core scale[0

01[ Current ripples with preserved crest or eroded crest[Some ripple forms with curved bases may representwave ripples[0

02[ Mud!o}shoots[0

03[ Double mud layers "tidal#[0

04[ Sigmoidal cross bedding "tidal#[0

05[ Flaser bedding[06[ Occurrence of sand layers with traction structures in

discrete units\ but not as part of a vertical sequenceof structures\ such as the Bouma "0851# sequencewith basal graded division[ Base!missing {BoumaSequences| are products of bottom currents[0

Although deep!marine bottom!current reworked sandscan resemble tidal and shallow marine "outer shelf#deposits\ they can be recognized by their close associationwith other deep!marine facies\ such as turbidites\ debris!~ow deposits\ and hemipelagic mud[ In~uence of tidalforces can generate tidal deposits in deep!water settings[For example tidal rhythmites have been reported fromdeep!water estuaries "Cowan\ Cai\ Powell\ Seramur +Spurgeon\ 0887#[ Tidal features "e[g[\ double mud layers\sigmoidal cross bedding etc[# in ancient deep!water sandsin southeastern France\ o}shore Brazil\ and EquatorialGuinea have been observed[

I emphasize that no single criterion by itself is uniqueto bottom!current reworked facies[ Although many ofthe features listed above can be attributed to processesother than bottom!current reworking\ the association ofseveral of the above features in the Gulf of Mexico cores"Shanmugam et al[\ 0882a#\ along with the knowledge ofthe regional depositional setting\ greatly enhances thechance for recognizing bottom!current reworked facies[Distinguishing deposits of bottom currents from those ofoverbanking turbidity currents is especially critical indeveloping realistic depositional models and in eva!luating reservoir potential[ In the Gulf of Mexico\ hydro!carbon!bearings sands of bottom!current origin showhigh porosity values "14Ð39)#\ and high permeabilityvalues "099Ð0799 mD#[ From petroleum explorationpoint of view\ bottom current is a viable mechanism thatis capable of forming {clean| sands in the deep sea[

4[ Deep!water facies models

4[0[ Philosophy

A facies model\ by de_nition\ must act as a norm\ aframework\ a predictor\ and a basis for interpretation"Walker\ 0881b#[ My view is that facies models may be

more useful in interpreting subaerial and shallow!marinedeposits than deep!water deposits[ Unlike ~uvial and del!taic environments\ it is not practical to observe and ana!lyze features and processes directly in deep!waterenvironments[ We are also hampered by our inability toemulate deep!water conditions realistically in laboratoryexperiments[ This is further complicated by the problemsof comparing modern and ancient deep!water systems"Shanmugam et al[\ 0874a\ 0874b^ Mutti + Normark\0876^ Pickering et al[\ 0878#[ As a result\ deep!water faciesmodels are mostly based on incomplete observationsmade on modern and ancient systems[ This is one ofthe reasons why past attempts to develop general faciesmodels of deep!water systems "e[g[\ Mutti + Ricci Lucchi\0861^ Normark\ 0867^ Walker\ 0867# have failed[

The attraction to a facies model is that it serves as ashort cut to complex geologic interpretations[ Anderton"0874# believes that facies models are ephemeral\ and thateach facies model is unique[ Because each facies model isunique to a certain environment\ we are programmed toalign our thinking and observation along a pre!destinedpath[ In maintaining the integrity of the model\ we areoften forced to de!emphasize features that are {foreign|to the model[ The reality is that those {foreign| featuresare as important as the features advocated by the model[This is where facies models have the potential to restrictour ability to observe objectively all the features that arepresent\ irrespective of whether those features are part ofa model or not[ After all\ a facies model is developed froma local example\ and we cannot expect it to encompass allpossible variabilities[ In criticizing the application of rigid~uvial facies schemes to the rock record\ Leeder "0886#cautioned\ {{the main philosophical reason is that it\ andother schemes like it\ are lazy intellectually and deny thegreat potential richness of the sedimentary record\ full ofpossible variation not adequately taped by rigid classi!_cation[|| Once a model is established\ it is not easy toerase it from our mind or practice[ Science is a journey\whereas facies models terminate that journey and becomethe _nal destination[

4[1[ Order vs chaos in nature

Any attempt to construct a general facies model is anattempt to distill order in nature[

Order is an arrangement in which everything is organ!ized in its right place\ whereas chaos is disorganization[Order is believed to facilitate prediction because of itssimplicity\ whereas chaos is believed to deter predictionbecause of its complexity[ This is why turbidite faciesmodels ~ourished in the 0859s "e[g[\ Bouma\ 0851#\ the0869s "e[g[\ Piper\ 0867#\ and the 0879s "e[g[\ Lowe\ 0871#[But I stress that aspects of nature are chaotic and there!fore the study of chaos is equally important in under!standing the geologic record[

The common tendency is to over!emphasize order and


de!emphasize chaos in facies models[ This practice hasled to a skewed representation of order in the rock record[For example\ Moiola and Shanmugam "0873# interpretedthe Pennsylvanian Jackfork Group in the Ouachitas asbeing composed of classic turbidites organized into chan!nels "thinning up sequences# and crevasse splays "thick!ening up sequences#[ This was based on observations ofthe trends on large!scale packages "several meters thick#without paying much attention to details at the cen!timeter scale[ Later\ Shanmugam and Moiola "0884# rein!terpreted the same Jackfork Group as being composedof deposits of sandy debris ~ows\ slumps\ and bottomcurrent reworking stacked in a disorganized "i[e[\ chaotic#a manner[ This later study was based on detailed obser!vations made at the centimeter to decimeter scale[ Wehave observed the chaotic occurrence of slump and debris~ow facies at core scale\ but these same chaotic facies arestacked in an orderly and predictable manner at a largerscale in Equatorial Guinea "Famakinwa + Shanmugam\0887#[

The distinction between order and chaos is not alwaysclear cut\ and may change with time[ What was onceconsidered order may later be considered chaos[ Forexample\ the Bouma Sequence is considered to representdepositional order of a single turbidity current "Fig[ 12#[This is true only if we assume that no process other thana turbidity current can generate the Bouma Sequence[ AsI have pointed out "Shanmugam\ 0886a#\ the BoumaSequence can also be explained by the combination of asandy debris ~ow and bottom!current reworking[ If so\the Bouma Sequence is no longer a representation ofnatural order by a single process[

Although Mutti and Normark "0876# routinely classifyall deep!water systems as 0st\ 1nd\ 2rd\ 3th and 4th orderfeatures\ core studies have shown that chaotic pattern isthe norm in many deep!water systems at the core scale"Shanmugam et al[\ 0884a#[ Pickering et al[ "0884# applieda bounding surface hierarchy\ composed of six orders\ todeep!water deposits[ This bounding surface concept wasoriginally developed for ~uvial deposits "e[g[\ Miall\0874#[ However\ ~uvial processes and submarine pro!cesses are not one and the same "Table 0#[ The perceivedorder in deep!water systems\ at least in part\ is due tomodel!driven description of deep!water strata[

4[2[ Generalization vs precision of facies models

The applicability of a facies model depends on its gen!eralization[ The more general a facies model gets\ themore applicable the model becomes beyond its orig!ination point[ On the other hand\ the more precise afacies model gets\ the less applicable the model becomesbeyond its birth place[ For these reasons\ generalists tendto lump and di}use the details\ whereas purists prefer tosplit the details[ For example\ a single division in theBouma Sequence has been correlated with _ve divisions

of _ne!grained turbidite sequence "Fig[ 12#[ The challengein constructing useful facies models has always beenwhere to draw the line between lumping and splitting[This is particularly true for deep!water systems becauseof their highly complex and variable facies distribution[A classic example is the basal division in the BoumaSequence "Ta# in which both massive and graded beds arelumped together "Fig[ 6#[ This has led to eight di}erentinterpretations "e[g[\ grain ~ows\ sandy debris ~ows\high!density turbidity currents etc[# for the basal massivedivision of the Bouma Sequence "see Shanmugam\0886a#[ Clearly\ the Bouma Sequence cannot be the normfor turbidites[

4[3[ Problems with turbidite facies models

Bouma "0851# proposed the _rst vertical facies modelfor turbidites "Fig[ 12#\ which eventually has beenreferred to as the Bouma Sequence and comprises _vedivisions "Ta\ Tb\ Tc\ Td\ Te#[ Later workers realized thatthe muddy division of the Bouma Sequence "Te# was notadequate to satisfactorily represent all divisions that arepresent in muddy turbidites "e[g[\ Piper\ 0867#[ This real!ization led Stow and Shanmugam "0879# to propose anew vertical facies model just for the _ne!grained tur!bidites with nine divisions "T9\ T0\ T1\ T2\ T3\ T4\ T5\ T6\T7#[ Similarly\ Lowe "0871# introduced a new verticalfacies model for coarse!grained turbidites "i[e[\ depositsof high!density turbidity currents# with six divisions "R0\R1\ R2\ S0\ S1\ S2#[

In natural environments\ there is only one type ofturbidity current\ a Newtonian ~ow in which sediment issuspended by ~uid turbulence[ Natural turbiditycurrents\ no matter what grain size sediment they trans!port\ will always behave the same in terms of ~uid dynam!ics[ Therefore\ an ideal turbidity current that carriesgravel to mud size material should deposit a continuumof divisions representing coarse!grained turbidites at thebottom "R0\ R1\ R2\ S0\ S1\ S2#\ classic turbidites in themiddle "Ta\ Tb\ Tc\ Td\ Te#\ and _ne!grained turbidites atthe top "T9\ T0\ T1\ T2\ T3\ T4\ T5\ T6\ T7#[ There are nophysical laws that dictate that turbidity currents\ whichcarry coarse sediment must cease deposition at Lowe|s"0871# S2 division or turbidity currents that carry _nesediment must commence deposition with Stow andShanmugam|s "0879# T9 division[ The established div!isional boundaries between these three ideal facies modelsis an arti_cial one[ In other words\ there is no ~uiddynamics reason why a turbidity current carrying a gravelto mud sediment load cannot deposit all its divisions fromgravel "R0# to mud "T7#[ In fact\ Lowe "0871# suggested acontinuum of deposits from coarse!grained turbidites toclassic turbidites "R0 to Te# totaling 00 divisions[ I haveadded the nine divisions of _ne!grained turbidites to thiscontinuum "Fig[ 13#[ In this composite model\ an idealturbidite bed should comprise a total of 05 divisions\


Fig[ 12[ Existing vertical facies models of "0# coarse!grained turbidites "Lowe\ 0871#\ "1# classic turbidites "also known as the Bouma Sequence#\ and"2# _ne!grained turbidites "Stow and Shanmugam\ 0879#[ Correlation of the S2 division of coarse!grained turbidites with the Ta division of the BoumaSequence is after Lowe "0871#[ Correlation of various divisions between classic turbidites and _ne!grained turbidites is after Pickering et al[ "0878#[

Fig[ 13[ A schematic diagram showing downslope changes in turbidite divisions from coarse!grained turbidites "Lowe\ 0871#\ through classic turbidites"Bouma\ 0851#\ to _ne!grained turbidites "Stow and Shanmugam\ 0879#[ A total of 05 divisions is expected from an ideal turbidite bed\ however\ noone has ever documented such a turbidite bed[ Diagram is from Lowe "0871#\ and modi_ed using concepts from Pickering et al[ "0878#[

eliminating four overlapping divisions[ Such an expec!tation is not unrealistic because many deep!watersequences contain gravel to mud range lithologies[ Tomy knowledge\ no one has ever documented a complete

turbidite bed with 05 divisions in modern or ancientdeposits[ The absence of a complete turbidite bed with05 divisions in the geologic record suggests that the idealturbidite facies models are wrong[


4[4[ Problems with traction!carpet models

The notion that traction carpets in high!density tur!bidity currents are analogous to bed!load transport inriver currents is ~awed[ This is because deposition from{traction carpets| occurs in the absence of sand movementby true traction\ and in the presence of pervasive laminarshearing "Middleton\ 0869#[ For this reason\ Carter"0864# abandoned the use of the term {traction carpet|[

The precise mechanism of a traction carpet has beenthe subject of speculation for nearly four decades sinceits inception by Dzulynski and Sanders "0851#[ Thisspeculation has resulted in the following multiplicity ofmodels and processes] "0# ~uxoturbidity currents\ "1#grain ~ows\ "2# slurry ~ows\ "3# ~owing!grain layers\ "4#inertia!~ow layers\ "5# ~uidized ~owing grain layers\ "6#avalanching ~ows\ "7# liqu_ed cohesionless coarse!par!ticle ~ows\ "8# high!density turbidity currents\ and "09#sandy debris ~ows "see Sanders\ 0854^ Carter\ 0864^Lowe\ 0871^ Postma et al[\ 0877^ Shanmugam\ 0886a^Sanders + Friedman\ 0886#[ This many terminologies fora single ~ow type can only mean that we do not have aclear understanding of the mechanics of the ~ow involvedin the {traction carpet|[

The most recent addition to the long line of traction!carpet models is the one called {laminar sheared layers|"Vrolijk + Southard\ 0886#[ According to Vrolijk andSouthard "0886#\ {laminar sheared layers| are products ofturbidity currents[ As the name {laminar sheared layers|implies\ these laminar layers are products of laminar"plastic# ~ows^ therefore\ they cannot be products of tur!bulent turbidity currents "see Middleton\ 0882#[

Another recent addition to the plethoric family of trac!tion carpets is the one proposed by Sohn "0886#\ whostates\ {{the model is generally qualitative and partlyspeculative\ not fully supported by experimental or obser!vational evidence[|| Such speculative models would havebeen appropriate when the concept of traction carpet was_rst introduced[ What we need today is hard data\ notmore speculations[

Sohn "0886# states\ {{It seems that traction carpets andoverlying turbulent ~ows cannot be separate entities\ theformer being subordinate to the latter||[ Using Sohn|slogic\ one could argue that turbidity currents\ whichdevelop on top of debris ~ows through dilution of debris~ows "see Fig[ 00#\ are not separate entities from debris~ows[ In other words\ one could classify these overridingturbidity currents as {low density debris ~ows| becausethey are derived from the debris ~ows below "Fig[ 00#[The problem with this approach is that it fails to take intoaccount the rheology and sediment!support mechanism\which are the foundation for classifying sediment!gravity~ows "e[g[\ Lowe\ 0868#[

Sohn "0886# states\ {{Traction carpets can be separateentity only when they move independently of the over!lying ~ows\ for example\ on steep fan!delta slopes||[ First

of all\ it is misleading to call a layer a {traction carpet|without the overlying turbulent ~ow[ Secondly\ what arethe criteria for distinguishing deposits of a density!strati!_ed ~ow "i[e[\ traction carpet with overlying turbulent~ow# from that of a density!uni_ed ~ow "i[e[\ sandy debris~ow without overlying turbulent ~ow#< Norem\ Locatand Schieldrop "0889# suggested that a turbidity currentevolved from a debris ~ow "density strati_ed# may outrunthe mother debris ~ow and become a density!uni_ed tur!bidity current "Shanmugam\ 0886a#[ In cases like this\what criteria should be used in recognizing traction car!pets<

Sohn "0886# in his _g[ 3 claims that traction carpetscan generate _ve types of deposits\ namely\ "0# thick!bedded and inversely graded\ "1# thick!bedded and mass!ive with only the basal part inversely graded\ "2# di}uselystrati_ed\ "3# thinning!upward strati_ed\ and "4# thick!ening!upward strati_ed[ If this is true\ virtually all deep!water sands could be interpreted as deposits of tractioncarpets; The issue here is how to distinguish these _vedeposits of traction!carpet origin from those of otherprocesses "e[g[\ sandy debris ~ows# that also generateinversely graded or massive sands[

Finally\ the problems surrounding the concept of {trac!tion carpet| can be traced\ at least in part\ to another con!fusing concept known as {~uxoturbidity current| "Kuenen\0847#[ The link is that both concepts advocate the presenceof non!turbulent "i[e[\ laminar# layers at the base of adepositing turbidity current "Carter\ 0864#[AlthoughCarter"0864# favored the use of the term {~uxoturbidites| for thedeposits of ~uxoturbidity currents\ Hsu "0878# pointed outthat no one seems to know what the term {~uxo| stands forin ~uxoturbidites[ Furthermore\ the term {~uxoturbidites|was _rst applied to {sand!avalanche deposits| in the PolishCarpathians by Dzulynski et al[ "0848# because Ph[ H[Kuenen felt that the term {sand!avalanche deposits| wastoo long\ and that the term {~uxoturbidites| was short\descriptive\ and thereforemore appropriate "seeHsu "0878#\for a fascinating history behind the application of the term#[Until we decide to discard these meaningless terminologies\problems will persist[

4[5[ Problems with contourite facies modes

Stow et al[ "0887# proposed a composite facies modelfor muddy and sandy contourites "Fig[ 14#[ This modelis the same as the one proposed for the modern FaroDrift that parallels the northern margin of the Gulf ofCadiz\ south of Portugal "Gonthier et al[\ 0873#[ It con!sists of a basal negatively "inversely# graded unit overlainby a positively "normally# graded unit "Fig[ 14#[ Theboundary between the positively graded and negativelygraded units occurs in the middle of a massive "struc!tureless# sandy silt unit "Fig[ 14#[ Sand and silt compriseonly 4) of the sediment[ The grain size vertically variesfrom mud at the bottom\ sandy silt in the middle\ and


Fig[ 14[ Composite facies model for muddy and sandy contourites "Stow et al[\ 0887#[ Vertical grain size variation and bioturbation\ advocated bythe model\ are not unique to contour currents[ This general model for sandy contourites is based on an example "Faro Drift# that is 84) mud\ andonly 4) sand and silt "see Gonthier et al[\ 0873#[

mud at the top[ Bioturbation is ubiquitous throughout[Gonthier et al[ "0873# attributed the vertical change ingrain size "vertical increase followed by vertical decrease#to corresponding variations in current velocity "verticalincrease followed by vertical decrease# associated withthe deep Mediterranean Out~ow[

Stow et al[ "0887# have provided a precise de_nition of{contourites|\ which is good[ By their de_nition\ con!tourites are sediments that have been deposited orreworked by geostrophic bottom currents that followbathymetric contours in water depths greater than 299m[Stow et al[ "0887# do not consider {contourites| to includethe deposits of bottom currents induced by surface windcurrents\ tidal currents\ or clear!water canyon currentsthat operate in water depths greater than 299m[ Whenwe deal with ancient strata\ it is not always possible todi}erentiate whether a bottom current that followedbathymetric contours reworked a bed or a bottom currentthat did not follow bathymetric contours reworked a bed[This is because not all bottom currents follow bathymetriccontours "e[g[\ The Loop Currents in the Gulf of Mexico#[

Therefore\ Stow et al[|s general contourite model is appli!cable only to those ancient examples where it can bedemonstrated that the geostrophic currents followedbathymetric contours in paleo water depths in excess of299m[ In other words\ the general model of Stow et al["0887# is of limited value^ it fails to represent a variety ofbottom currents that are common in the deep sea[

The term {sandy| is used loosely for both quartz sands"i[e[\ clastic contourites of Stow et al[\ 0887# and biogenicsands "i[e[\ biogenic contourites of Stow et al[\ 0887#[Quartz sands have a bulk density of 1[54 g:cm2\ whereasbiogenic sands "mostly foraminiferal calcitic grains# havea bulk density of 1[60 g:cm2[ More importantly\ for!aminiferal sands are globular in shape with hollowinteriors\ whereas\ quartz grains are variable in shapewith dense interiors[ As a consequence\ foraminiferalsands\ in comparison to quartz sands\ generally ~oat inwater\ although calcite has a higher bulk density thanquartz; These di}erences are important in controllingthe settling velocity of quartz and foraminiferal sands[Di}erences in settling velocity would generate di}erent


disposition between quartz and foraminiferal sands[Therefore\ lumping both siliciclastic and biogenic sandsin the {sandy contourites| category is confusing from asettling velocity point of view[

In the original model of the Faro Drift\ sands and siltsform about 4) of the sediment "Gonthier et al[\ 0873#[The composite contourite model is claimed to be a generalmodel for both muddy and sandy contourites "Stow etal[\ 0887#[ It is misleading to propose a sandy contouritemodel based on an example "Faro Drift# that is composedof more than 84) mud[

In discussing the composite contourite facies model"Fig[ 14#\ Stow et al[ "0887# state that in deep!water drifts\{{[ [ [ direct evidence of current in~uence is often meagre||[I _nd it ironic that a general model for {contour currents|has neither strong direct evidence for currents nor evi!dence for currents that follow bathymetric contours[ Afacies model is expected to reveal something unique abouta particular environment or process^ the contourite modeldoes not reveal anything unique about contour currents[

The model "Fig[ 14# strongly suggests that bioturbationis characteristic of contourites "see also Lovell + Stow"0870##[ This was based on the belief that active bottomcurrents would increase the oxygen concentration of thewater mass "Chough + Hesse\ 0874#\ and thereby wouldincrease the activity of organisms[ However\ Tucholke\Hollister\ Biscaye and Gardner "0874# suggested that thedegree of preservation of bioturbation is a function ofbottom current intensity^ strong bottom currents do notfavor preservation of biogenic structures[

There is nothing unique about bioturbated mud indeep!water sequences that suggests deposition from con!tour!following\ deep geostrophic currents[ Bioturbatedmud is quite common in areas that are not a}ected bycontour currents in the deep sea[ Even if bioturbation isprevalent in areas of contour currents\ bioturbation doesnot reveal anything unique about contour currentsdirectly[ In the rock record\ convincing cases of con!tourites have been documented without the presence ofbioturbation[ For example\ in the Neoproterozoic Sheep!bed Formation "Windermere Supergroup# of Canada\certain deep!water intervals have been interpreted to bedeposits of contour currents\ even though there is nobioturbation "Dalrymple + Narbonne\ 0885#[

Many workers have interpreted ancient strata as {con!tourites| or bottom!current reworked deposits "Stanley\0877^ Mutti\ 0881^ + Shanmugam et al[\ 0882a#[ In theirdisagreement over the above interpretations\ Stow et al["0887# stated\ {{the attempt to address the problem solelyfrom work of ancient turbidite sequences "e[g[\ Stanley\0877^ Mutti\ 0881^ Shanmugam et al[\ 0882a# has led toseveral serious errors in interpretations [ [ [||[ Admittedly\the features of these ancient examples have very little incommon with the features of the general facies modeldeveloped from a modern drift "Stow et al[\ 0887#[ Myview is that we don|t fully understand the similarities and

di}erences between modern and ancient bottom currents[Until we do\ any general facies model of contourites is ofonly limited practical value[

5[ Submarine!fan models

Submarine fans are considered to be products of pri!marily turbidity currents[ However\ a few modern fanshave been ascribed to debris ~ows "Elverhoi et al[\ 0886#[Submarine!fan models\ based on turbidite concepts\ havebeen the most in~uential sedimentologic tool in pet!roleum industry for interpreting deep!water environ!ments[ These models have a long history\ and it is worthanalyzing how they have in~uenced both sedi!mentologists and sequence stratigraphers[

5[0[ Modern!fan model

Normark "0869# presented the _rst widely used modelfor modern submarine fans based on studies of small\sand!rich\ fans such as the San Lucas and Navy fans\o}shore of California[ He introduced the term {suprafan|to describe the lobe!shaped bulge found immediatelydownfan of the termination of the major feeder channelon modern fans[ This morphologic feature was pre!sumably formed by rapid deposition of coarse sedimentby turbidity currents at the termination of the upper!fanvalley "Normark\ 0869\ 0867#[ The suprafan lobe wasthought to exhibit an overall mounded\ hummocky mor!phology in high!resolution seismic data because theirregular surface of the suprafan produced multiple andoverlapping hyperbolic re~ections "Normark\ 0880#[

5[1[ Ancient!fan model

Mutti and co!workers proposed submarine!fan modelsbased on outcrop studies in Italy and Spain\ which popu!larized the concept of submarine fans with channels inthe middle!fan setting and depositional lobes in the lower!fan setting "Mutti + Ricci Lucchi\ 0861^ Mutti\ 0866#[Mutti and Ghibaudo "0861# were the _rst to apply theterm {depositional lobe| to ancient deep!sea fansequences[ The general characteristics of the depositionallobes of ancient submarine fans "Mutti + Ghibaudo\0861^ Mutti + Ricci Lucchi\ 0861^ Mutti\ 0866# includethe following] "0# they are considered to develop at ornear the mouths of submarine!fan channels analogous todistributary mouth bars in deltaic systems^ "1# they showan absence of basal channeling^ "2# they usually displaythickening!upward depositional cycles composed ofclassic turbidites^ "3# their common thickness range is 2Ð04m\ and "4# they exhibit sheet!like geometry[

5[2[ General!fan model

Walker "0867# combined the major elements of Nor!mark|s "0869# model for modern fans with facies concepts


Fig[ 15[ Evolution of concepts on seismic mounds[ Normark "0869# _rst proposed the seismic mound concept based on his study of suprafan lobesof modern systems[ Mitchum "0874# proposed a general seismic model for submarine fans\ based on the seismic mound concept of Normark "0869#\in which lobes exhibit an external mounded geometry with internal bidirectional downlaps[ Vail et al[ "0880# proposed a basin!~oor fan model\ whichis based on Mitchum|s "0874# lobe concept[ Thick upward arrows show the link between seismic mound concepts[ See text for details[

of ancient submarine fans "Mutti + Ricci Lucchi\ 0861#\and advocated a general fan model with a single feederchannel in the upper!fan area and suprafan lobes in themiddle:lower fan areas[ Subsequently\ this general fanmodel\ became in~uential in hydrocarbon explorationand production because of its predictive capabilities[

5[3[ Sequence!stratigraphic models

The concept of suprafan lobes with mounded seismicforms had its in~uence in seismic sequence stratigraphy"Fig[ 15#[ Sarg and Skjold "0871# applied the suprafanconcept to the Paleocene sands in the Balder area\ NorthSea and mapped eight distinct suprafan lobes with moun!ded seismic geometries[ Each individual mound was inter!preted as a {suprafan lobe| containing an inner fan with

_ning!upward channelized deposits and an outer fanfringe with coarsening!upward sheet sands "Sarg +Skjold\ 0871#[ Mitchum "0874#\ following Normark|s"0869# model\ proposed a general seismic model forancient fans that consist of an upper and a lower fan"Fig[ 15#[ The upper fan consists of leveed channels "i[e[\channel!levee complex of Normark "0869#\ and the lowerfan is composed of lobate and mounded deposits "i[e[\suprafan of Normark\ 0869#[ It is important to note thatMitchum "0874# equated mounded seismic facies withsheet!like turbidite sandstones of ancient depositionallobes[ In Mitchum|s "0874# model\ a lobe is consideredto exhibit mounded external form and bidirectionaldownlap\ suggesting that the lobe is fully developed andhas well!de_ned outer limits[

In a sequence!stratigraphic framework\ the lowstand


systems tract is composed of the basin!~oor fan\ theslope fan and the prograding wedge "Vail\ 0876^ Vail\Audemard\ Bowman\ Eisner + Perez!Cruz\ 0880#[ Slopefans and basin!~oor fans of Vail "0876# represent Mit!chum|s "0874# upper fan with leveed channels and lowerfan with seismic mounds\ respectively "Fig[ 15#[ In short\the basin!~oor fan concept is nothing but a combinationof Normark|s "0869# suprafan lobe concept "i[e[\ moun!ded seismic geometry# and Mutti and Ricci Lucchi|s"0861# depositional lobe concept "i[e[\ sheet!like sand!stone bodies#[ However\ there is an important distinctionbetween fan models of sedimentology and sequence stra!tigraphy[ In sedimentologic fan models\ channels andlobes are contemporaneous elements^ whereas insequence!stratigraphic models\ leveed fan channels arepart of the slope fan\ and are therefore younger\ and notcontemporaneous with the lobes\which are part of theolder underlying basin!~oor fan[

The application of shallow!water sequence!strati!graphic terms\ such as {maximum ~ooding surface| and{parasequence| to deep!water sequences creates a con!ceptual problem[ For example\ Normark\ et al[ "0886#have applied the term {maximum ~ooding surface| to themodern Amazon[ Fan[ The term {~ood| literally meansthat a river or sea is ~owing over its usual limits[ At 2999Ð3999m of water depths\ irrespective of sea level changes\nothing is ~owing over its usual limits[ The closest thingto a {~ooding| event in bathyal environments is the {over!banking| of turbidity currents from channels[ Althoughthis ~ooding surface on the Amazon Fan may haveoccurred at a time of ~ooding of the time!equivalentAmazon shelf\ the term {maximum ~ooding surface| at2999Ð3999m of water depths is a conceptually confusingone[ This example exempli_es the potential for confusionwhen we use sequence!stratigraphic terminologies in asedimentologic context[

Another example is the application of the par!asequence concept to deep!water "i[e[\ bathyal# turbiditesands of the Kakegawa Group in Japan "Sakai +Masuda\ 0885#[ By de_nition\ a parasequence is a depositof a paracycle "Van Wagoner et al[\ 0877^ Kamola + VanWagoner\ 0884#[ A parasequence is a relatively con!formable succession of genetically related beds or bedsetsbounded by ~ooding surfaces or their correlative surfaces"Van Wagoner et al[\ 0877#[

Because a parasequence is bounded by ~oodingsurfaces\ recognition of ~ooding surfaces is the key toestablishing a parasequence[ Van Wagoner et al[ "0877#de_ned a ~ooding surface as a surface that separatesyounger from older strata across which there is evidenceof an abrupt increase in water depth[ Sakai and Masuda"0885# have recognized parasequence boundaries in out!crops[ Accordingly\ these parasequence boundaries mustcorrespond to ~ooding surfaces[ In shallow!waterenvironments\ it is possible to recognize ~ooding surfacesbecause small changes in water depths "i[e[\ a few m#

are re~ected in the deposits[ However\ in bathyal waterdepths minor changes in water depths cannot be recog!nized[ The common tendency to interpret a mudstoneinterval in deep!water sequences as evidence for increas!ing water depths is not meaningful[ Condensed sectionscommonly are used as evidence for a rise in sea level[However\ condensed sections simply re~ect low rates ofdeposition "Loutit\ Hardenbol + Vail\ 0877#\ and cannotbe routinely equated with a marine ~ooding surface ora rise in sea level[ Therefore\ it is not clear what theparasequence boundaries recognized by Sakai andMasuda "0885# represent in terms of changing waterdepths[

A parasequence tends to show a gradual upward shal!lowing trend within the interval bounded by ~oodingsurfaces[ Sakai and Masuda "0885# do not present anyevidence for upward shallowing trends within the par!asequences in the Kakegawa Group[ Considering thatthe sands deposited by turbidity currents and mass ~owsin deep!water environments occur episodically\ in a mat!ter of hours or days "e[g[\ earthquake induced mass~ows#\ it is not practical to apply the parasequence con!cept to deep!water deposits in terms of changing waterdepths "i[e[\ upward shallowing followed by sudden deep!ening#[ In short\ there are no tools to recognize par!asequences in deep!water deposits "Shanmugam\ 0886b#[

5[4[ Abandonment of submarine!fan models

Re~ecting on the current unpopularity of submarine!fan models\ Miall "0888# opined\ {{the simple\ all!purposesubmarine!fan model of Mutti and Ricci Lucchi "0861#and Walker "0867# served the geological community wellfor about a decade\ but is now all but obsolete||[ Thereare good reasons for the demise of submarine!fan models[

Data gathered from the modern Navy Fan since thepublication of the suprafan lobe concept revealed thatthe {suprafan| area of modern fans is composed of acomplex array of channel\ lobe and large!scale scourelements[ This led Normark "0880# to reassess the validityof his suprafan concept] {{[ [ [ the suprafan concept is nolonger viable as a mappable\ de_ning structure of tur!bidite systems||[ Because the morphologic charactersticsof modern suprafan lobes are either not preserved in therock record or they cannot be planimetrically mapped inoutcrops\ Normark "0880# abandoned his {suprafan lobe|concept altogether[ Walker "0881a# also abandoned hisgeneral fan model by stating\ {{A submarine fan modelof the channel!depositional lobe type\ in~uential in itstime\ but now obsolete because it ignored externalcontrols\ especially sea level ~uctuations||[

The general premise behind popular fan models"Walker\ 0867^ Mitchum\ 0874^ Vail\ 0876#\ which equa!ted the suprafan lobe concept of modern fans "Normark\0869# with depositional lobe concept of ancient fans"Mutti + Ricci Lucchi\ 0861#\ was ill!founded because]


"0# modern suprafan lobes are de_ned on the basis ofconvex!upward surface morphology observable in high!resolution seismic data\ but their internal architectureand sedimentary facies are not known due to lack of longcores from closely spaced wells^ "1# concepts of ancientdepositional lobes are based on internal architectureobservable in outcrop:core\ but their true surface mor!phology and seismic expression are not known becauseof discontinuous outcrops\ tectonic complications\ diag!enesis\ and thin lobe packages "2Ð04m#^ "2# concepts ofmodern suprafan lobes were developed from convergentcontinental margins\ whereas sequence!stratigraphic con!cepts were developed from divergent continental margins^"3# depositional lobes using Mutti|s "0866# criteria havebeen documented in the ancient rock record\ but havenot been recognized in modern submarine fans "Flood etal[\ 0884#^ and "4# modern suprafan lobes do not formdiscrete mappable units "Normark\ 0880#\ whereasancient depositional lobes do[ In short\ the data frommodern and ancient fans simply are not compatible tomake any meaningful synthesis "Shanmugam et al[\ 0874^0877#[

By abandoning the suprafan lobe concept\ Normark"0880# e}ectively eliminated a major source of confusionin the literature[ However\ Normark "0880# also createdmajor problems by applying the term {depositional lobe|to the modern Navy fan[ This is because the lobes onmodern Navy fan have not been cored to su.cient depthsto establish the thickening!up trends and sheet!like geo!metries of true depositional lobes are present\ as requiredby Mutti|s "0866# de_nition of depositional lobes[ Coredlower!fan intervals in the modern Amazon Fan also donot show thickening!up trends characteristic of {lobes|"Normak\ et al[\ 0886#[ Although the outer fan area ofthe Mississippi fan is termed {depositional lobe| "Nelson\Twichell\ Schwab\ Lee + Kenyon\ 0881#\ core from thisarea is composed primarily of slumps and debris ~owsrather than turbidites "Nelson et al[\ 0881#[ In fact\ I amnot aware of a single published example of a depositionallobe from modern fans that has had its turbidite faciesand thickening!up trends documented using conventionalcore data\ or its laterally continuous\ sheet!like\ sand!body geometry documented by correlation of sand unitsbetween closely spaced wells[

Problems also exist in recognizing depositional lobesin the ancient rock record[ The thickening!up trend hasalways been an important criterion for recognizing depo!sitional lobes "Mutti\ 0866#[ Recently\ however\ Mutti"0881# interpreted certain intervals with thinning!uptrends as depositional lobes in the Pennsylvanian Jack!fork Group in the Ouachitas[ By de_nition\ depositionallobes are characterized by classic turbidites "Mutti\ 0866#[However\ I think that the intervals that Mutti "0881#interpreted as depositional lobes in the PennsylvanianJackfork Group are dominated by slumps and debris~ows\ not turbidites "Shanmugam + Moiola\ 0883#[

The irregular upper surface of the suprafan lobe pro!duces multiple and overlapping hyperbolic re~ectorscausing mounded\ hummocky morphology "Normark\0880#[ Modern slides and debris ~ows also generatemounded\ hummocky morphology because of theirirregular upper surfaces "Jacobi\ 0865^ Embley\ 0879^Prior et al[\ 0873#[ Therefore\ a mounded\ hummockymorphology is not unique to suprafan lobes[ In fact\irregular upper surfaces are more characteristics of slides\slumps and debris ~ows in modern oceans than turbidites[Unlike turbidity currents\ the plastic rheology and ~owbehavior "like wet concrete# of slumps\ slides and debris~ows allow them to form deposits with topographic reliefabove the existing sea ~oor "e[g[ Jacobi 0865^ Embley +Jacobi\ 0866^ Embley 0879^ Prior et al[\ 0873^ Hiscott +Aksu\ 0883#[

The conceptual basin!~oor fan model\ characterizedby mounded seismic facies\ predicts sheet!like turbiditesands "Vail et al[\ 0880#[ However\ I\ along with severalco!workers\ have conducted detailed description andinterpretation of about 01\999 feet of core through anumber of mounded seismic forms of {basin!~oor fans|in the North Sea and Norwegian Sea[ These studies showthat turbidites are extremely rare in these mounded fea!tures "³0)#[ Mass!transport deposits\ especiallyslumps\ slides and debris ~ows\ are predominant in thecore "49Ð099)# taken from mounded seismic facies"Shanmugam et al[\ 0884a#[ Our data also suggest thatsome of these sands are laterally discontinuous "Shan!mugam et al[\ 0883#[ While features identi_ed as basin!~oor fans may occur at speci_c and predictable strati!graphic positions within a depositional sequence and pro!duce characteristic seismic facies and re~ection patternson seismic data\ our core study indicates that basin!~oorfans do not represent speci_c depositional facies "e[g[\turbidites# and geometries "i[e[\ sheet!like# as the modelpredicts[ I suggest that seismic mound models "e[g[\ basin!~oor fan# should be abandoned because they are notreliable and they are based on the now defunct suprafan!lobe model[

6[ Seismic facies and geometries

6[0[ Depositional processes

Seismic facies and geometries are used to classify deep!water systems into basin!~oor fans and slope fans in asequence!stratigraphic framework "Vail et al[\ 0880#\ andin turn\ these models are used to predict speci_c depo!sitional processes "e[g[\ turbidity currents#[ However\ asdiscussed above\ the term {turbidity current| has precisemeanings in terms of rheology "i[e[\ Newtonian#\ andsediment!support mechanism "i[e[\ turbulence#[ Evidencefor Newtonian rheology and ~ow turbulence cannot beestablished directly from seismic!re~ection pro_les or


wireline!log motifs^ rather\ these properties can only beascertained from actual sediment facies in cores oroutcrops[ Furthermore\ the interpretation of speci_c seis!mic facies and geometries "e[g[\ sheet\ mounded\ continu!ous\ hummocky etc[# as to sediment processes may varyfrom one worker to the next depending on one|s experi!ence[

6[1[ Mounded seismic facies of sheet sands

Deep!water sheet sands are a major attraction to thepetroleum industry because of their potential to holdlarge volumes of hydrocarbons and because their simplegeometry allows easy reserve calculations and hydro!carbon recovery[ Thus\ the appeal of a conventional sub!marine!fan model is that sheet sands can be predicted todevelop in outer fan areas and in front of distributarychannels by turbidity currents\ and that they appearmounded in seismic pro_les[ However\ care must be exer!cised in interpreting mounded seismic facies as sheetsands[

For example\ modern lower!fan deposits of the Ama!zon and Mississippi fans\ which contain sheet!like sands\show no evidence of mounded external geometry or sea!~oor relief on seismic data of any scale "e[g[ Damuth etal[\ 0877^ O|Connell\ Normark\ Ryan + Kenyon\ 0880^Shanmugam + Moiola\ 0880#[ Simply\ there are no datafrom either modern or ancient fans to support the viewthat sheet!like sandstones of submarine fans generate themounded seismic geometries that are characteristic ofbasin!~oor fans in the sequence!stratigraphic framework[Furthermore\ it is not clear to me why sheet!like sandbodies of depositional lobes on the lower portion of asubmarine fan would be expected to produce moundedfeatures with relatively steep convex!upward upper sur!faces in seismic sections "Shanmugam + Moiola 0880^Swarbrick\ 0880#[ Individual depositional lobes\ observedin outcrops with thicknesses ranging from 2 to 04m\are not thick enough to generate mounds that can bediscriminated on seismic re~ection pro_les[

6[2[ Channels and lobes

The outer fan areas of the modern Mississippi Fanwere used as the modern analog for turbidite fans withsheet!like geometries "Shanmugam\ Moiola\ McPherson+ O|Connell\ 0877b#[ Such a notion was based strictlyon parallel and continuous re~ection patterns observedon seismic pro_les[ However\ a SeaMARC 0A sidescan!sonar survey coupled with piston coring of a portion ofthe outer Mississippi Fan reveal that this portion of theterminus of the Mississippi Fan is not entirely sheet!likeas previously thought\ but channelized and dendritic innature "Twichell et al[\ 0881^ Twichell\ Schwab +Kenyon\ 0884#[ Also\ piston and gravity cores "Nelson etal[\ 0881^ Schwab et al[\ 0885# taken from channels in the

outer Mississippi Fan reveal that channels are _lled withdebris ~ows for the most part^ turbidites\ although alsopresent\ are not the dominant facies "Shanmugam\0886a#[

Although Twichell et al[ "0881# and Schwab et al["0885# still label the outer fan areas as {depositionallobes|\ true depositional lobes\ as de_ned by Mutti "0866#\are absent in the outer Mississippi Fan[ In other words\what were once considered to be non!channelized tur!bidite lobes of the Mississippi Fan have now been rein!terpreted to be channel!_ll debris ~ows[ This change ofinterpretation is the result of recent acquisition of high!resolution data[ In cases where high!resolution geo!physical data and core information are absent\ I preferto use the more general term {lobe form| for features thatappear lobate in map view\ but whose origin has not beenestablished using core information[

Amplitude extraction maps showing channel!likeforms "e[g[\ linear and sinuous patterns# are used to inter!pret channel!_ll turbidites\ but channels can also be _lledby debris ~ow\ slump and pelagic deposits[ Because pro!cesses that cut channels are not always the same processesthat _ll channels "Mutti + Normark\ 0876#\ process!based interpretation of channel!looking features in seis!mic data will always be a challenge[ Also\ debris ~owchutes and retrogressive slumping can create channel!like features[ More importantly\ spill over deposits fromdebris ~ow chutes may mimic gull!wing geometry ofchannel levee complexes in seismic data[ For thesereasons\ I prefer the general term {channel form| wheninterpreting seismic data\ without the bene_t of coreinformation needed to con_rm the presence of turbidites[

6[3[ High!amplitude re~ection packets "HARPs#

In the Amazon Fan\ channel bifurcation through avul!sion is thought to initially lead to deposition of unchan!nelized sandy ~ows in the interchannel area "Fig[ 16\top diagram#[ Subsequent channel and levee developmentand progradation over these sandy deposits "Fig[ 16\bottom diagram# produces a sheet!like geometry at thebase of the new channel!levee system that returns high!amplitude re~ections "HARPs# on seismic data "Flood\Manley\ Kowsmann\ Appi + Pirmez\ 0880^ Flood\ et al[\0884#[ These sheet!like HARPs overlain by a channel!levee system "gull!wing geometry# are in many waysidentical in appearance to a basin!~oor fan overlain by aslope fan in a sequence!stratigraphic framework[However\ there is a major di}erence between a basin!~oor fan and HARP[ For example\ a basin!~oor fan isformed by progradation primarily during lowstands ofsea level "allocyclic process#\ whereas HARPs are theresults of channel bifurcation "autocyclic process#[ Moreimportantly\ the basin!~oor fan and the slope fan are notcontemporaneous and form at di}erent times "Vail et al[\0880#^ whereas a HARP unit and its overlying channel!


Fig[ 16[ Channel bifurcation through avulsion on a deep!sea fan results in unchannelized sandy ~ows "top diagram# breaching the con_ning levee ofthe active channel through a crevasse and then spreading out initially as unchannelized ~ows into lower relief interchannel areas to form a sandydeposit termed a HARP unit\ because it forms a {high!amplitude re~ection packet| on seismic data "Flood et al[\ 0880#[ With subsequent\ establishmentof a new leveed channel over these sandy HARP deposits "bottom diagram# can result in sheet!like geometry "Flood et al[\ 0884#[ Sheet!like HARPsoverlain by channel!levee complex "gull!wing geometry# can mimic a basin!~oor fan overlain by a slope fan in a sequence!stratigraphic framework"see Shanmugam et al[\ 0884a#[ However\ a basin!~oor fan is formed by progradation during lowstands of sea level "allocyclic process# and is olderthan the overlying slope fan\ whereas HARPs are formed by channel bifurcation "autocyclic process# that are conteporaneous with channel!leveeformation[ Therefore\ caution must be exercised in interpreting seismic geometries in terms of processes[

levee system are essentially contemporaneous features"Flood et al[\ 0880^ Flood et al[\ 0884#[ This again illus!trates that caution must be exercised in interpreting seis!mic geometries in terms of processes[

6[4[ Seismic facies and geometries vs depositional facies

Calibration of cored intervals with seismic re~ectionpro_les suggests that seismic facies and geometries alonemay not be reliable indicators of depositional faciesbecause a single depositional facies "e[g[\ sandy debris

~ow# can return a variety of seismic facies or geometries"Fig[ 17#[ For example\ in the Faeroe Basin\ west ofShetlands\ conventional cores recovered from moundedseismic facies and geometries with bidirectional downlapare composed of sandy debris ~ows and slumps "Shan!mugam et al[\ 0884a#[ In the Agat area in the NorwegianNorth Sea\ mounded seismic facies with chaotic internalre~ections are documented in cores to be composed ofsandy debris ~ows and slumps "Shanmugam et al[\ 0883#[In the Gulf of Mexico\ sheet seismic facies and geometrieswith parallel and continuous re~ections are also com!


Fig[ 17[ Schematic diagram showing that a single depositional facies ofsandy debris ~ow can generate several seismic facies and geometries"e[g[\ mounded\ sheet\ and pinch out#[ See text for details[

posed of sandy debris ~ows "Shanmugam + Zimbrick\0885#[ In the Gryphon Field\ North Sea\ lateral pinchout geometries with irregular and discontinuous re~ec!tions are composed of sandy debris ~ows "Shanmugamet al[\ 0884a#[

A single seismic facies or geometry can represent morethan one depositional facies[ In the Ewing Bank 715 Fieldof Gulf of Mexico\ for example\ Plio!Pleistocene sandswere cored and interpreted to be deposited primarily bybottom currents "Shanmugam et al[\ 0882a#[ Calibrationof these cores with seismic pro_les suggests that there areno di}erences in seismic re~ection patterns between thesereworked sands and associated channel turbidites[ Inother words\ a single seismic facies can be returned fromtwo very di}erent depositional facies[

At present\ our understanding of the sedimentary fac!ies that form di}erent seismic facies and geometries ispoor because of insu.cient {ground truthing| by coredata[ Seismic facies of deep!water sequences can bedeceptive\ and therefore\ mapping of seismic facies indeep!water sequences should be done with the realizationthat these patterns may not represent distinct depo!sitional facies[ Core is needed to ground truth and cali!brate depositional facies with seismic facies[

7[ Depositional mud matrix in deep!water sands

Depositional "primary# mud matrix\ which occludesporosity and reduces permeability\ is of economic import!ance in evaluating the reservoir potential of deep!water

sands[ In the 0849s and 0859s\ turbidites were consideredto be poor reservoirs because of their high mud content[The {turbidite!greywacke!~ysch!dirty sand| linkage andits negative in~uence on petroleum industry is eloquentlysummarized by Sanders and Friedman "0886#[ Pettijohn"0846# championed the link between high detrital matrixof deep!water sandstones "greywackes# and their tur!bidity current origin[ In referring to turbidite sandstones\Pettijohn "0846# stated\ {{The second group\ therefore\probably owes its detrital matrix or {paste| to depositionfrom ~uids with higher sediment:~uid ratios[ Such mediaare the subaqueous turbidity ~ows found in some lakesand in many marine environments [ [ [||[

Sullwold "0859# reported high silt and clay content"02[4Ð23[4)# from sieve analysis of upper Miocene sand!stone beds that were interpreted to be turbidites[ Thefollowing comments of Sullwold "0850# re~ect the thenprevailing views in the early 0859s concerning the muddynature of turbidity currents and their deposits]

0[ {{A turbidity current is opaque and muddy "by de_!nition# [ [ [||

1[ {{Poor sorting is an expected feature in turbidites[||2[ {{The large percentage of silt and clay in these sands

has caused them to be termed wackes and graywackesby most workers[||

3[ {{Sorting is directly related to porosity\ and turbiditesmust therefore have less original porosity than shal!low!water sands [ [ [||

Although the term {greywacke| is no longer used syn!onymously with turbidites\ the above comments are stillvalid because turbidity currents are considered to be atype of sediment!gravity ~ow with Newtonian rheologyin which sediment is held in suspension by ~ow turbu!lence[ Sanders and Friedman "0886# emphasize\ {{Fromthe point of view of petroleum geology\ sands depositedfrom turbulent suspension are poorly sorted and includeslarge amounts of silt and clay||[ It makes sense that tur!bidity currents would deposit mud!rich sediment becauseit is easier to transport mud\ rather than sand or gravel\in turbulent suspension[

In the 0889s\ however\ there has been a tendency toperpetuate the opposite notion] i[e[\ turbidites are clean"i[e[\ mud poor# sands[ Mitchum\ Sangree\ Vail and Wor!nardt "0889\ 0882#\ for example\ considered the turbiditesof basin!~oor fans to be {{[ [ [ clean\ well sorted sandstonewith good reservoir quality||[ In my opinion\ this popularnotion is based on the misinterpretation of clean\ deep!water\ massive sands as {turbidites| using the tractioncarpet analogy "see Shanmugam et al[\ 0884a^ Shan!mugam\ 0885a#[ Some might even use the low mud con!tent of certain deep!water sands as a criterion forinterpreting them as turbidites[ As discussed earlier\experiments have shown that sandy debris ~ows canemplace sands with only minute amounts of clay "i[e[\9[4) by weight# "Marr et al[\ 0886#[ Therefore\ low mud


content does not appear to be a valid criterion for estab!lishing the turbidity current origin of deep!water sands[

Sanders and Friedman "0886# maintain that simply{dirty| "i[e[\ mud rich# sands are turbidites\ and {clean|"i[e[\ mud free# sands are non!turbidites[ When comparedto turbidity currents\ sandy debris ~ows have betterchances of depositing mud!poor\ clean\ sands for thefollowing reasons]

0[ Experiments have shown that sandy debris ~ows canemplace clean sands as basal layers "see section onExperimental Sandy Debris Flows#[

1[ Subaqueous debris ~ows commonly undergo dilutionduring transport "Hampton\ 0861#[ The dilution gen!erates turbidity currents due to the removal of mudfrom the underlying debris ~ow "Fig[ 00#[ This processnot only depletes the underlying debris ~ow of mudbut also enriches the overriding turbidity current withmud\ a kind of mass balance of mud[ The longer thedepletion of mud\ the cleaner the sand would becomein a debris ~ow[ As discussed earlier\ experiments haveshown that sandy debris ~ows are capable of operatingwith only minute amounts of clay "Marr et al[\ 0886#[

2[ Mud is an integral component of turbidity currentsthat are generated from debris ~ows[ Turbulence keepsthe mud in suspension during transport[ During depo!sition\ mud is emplaced along with the _ne!grainedsand[ Thus\ turbidite sands should always containmud "Sanders + Friedman\ 0886#[ Pure sand ~ows\without mud\ cannot support sand and gravel in tur!bulent suspension for long periods of time duringtransport\ and will collapse[ Therefore\ mud!freesandy turbidity currents are short lived\ and are notimportant sand transport mechanisms in the deep sea[

3[ Subaqueous debris ~ows are prone to develop hyd!roplaning "Mohrig et al[\ 0887#[ Furthermore\ debris~ows are laminar in state[ As a result\ subaqueousdebris ~ows with hydroplaning are not likely to erodethe sea!~oor and incorporate the eroded mud into the~ow[ In contrast to debris ~ows\ turbidity currents arealways turbulent in state "Middleton\ 0882#[ Tur!bulence tends to cause erosion of the sea!~oor\ andthe eroded sea!~oor mud invariably gets incorporatedinto the ~ow[

In summary\ the emplacement of {clean| sands in deep!water environments may be better explained by] "0# sandydebris ~ows\ and "1# bottom currents "Hubert\ 0853^Hollister\ 0856^ Shanmugam et al[\ 0882a#\ rather thanby turbidity currents[

8[ Perpetuation of the turbidite paradigm

In this section\ I have selected the following studiesin demonstrating how the turbidite paradigm has beenperpetuated during the past 49 years[

Early experiments of {the turbidity currents of highdensity| by Kuenen "0849# have been very in~uential[Unfortunately\ these experiments did not deal with trueturbidity currents[ Carter "0864# considered Kuenen|sexperimental turbidity currents as slurry ~ows\ a type ofdebris ~ows[ In commenting on Kuenen|s "0849# experi!ments of high!density turbidity currents\ Oakeshott"0878# stated\ {{[ [ [ it is obvious from the high content ofclay in these experimentally formed ~ows that they wereactually debris ~ows\||[

Middleton "0856# conducted experiments on {high!concentration turbidity ~ows|[ However\ Middleton|s"0856# experimental {high!concentration turbidity ~ows|meet all the criteria for mass ~ows "i[e[\ debris ~ows#\as de_ned by Dott "0852#] "a# they were ~ows of non!Newtonian ~uids that exhibit plastic behavior\ "b# theywere high!concentration ~ows in which the sediment issupported by dispersive pressure\ and "c# deposition fromthese ~ows occurred by {freezing|[ Therefore\ these exper!imental ~ows were not true turbidity currents "see Shan!mugam\ 0885a#[

Experiments on {high!density turbidity currents| byPostma et al[ "0877# have also been very in~uential[ As Ipointed out earlier\ these experimental ~ows are com!posed of both sandy debris ~ows and turbidity currents[According to Oakeshott "0878#\ Postma et al[ "0877#experimental ~ows\ {would probably be described asdebris or density modi_ed grain ~ows|[ In these experi!ments\ the term {high!density turbidity current| is aeuphemism for {debris ~ows| ever since it started withKuenen|s "0849# experiments[

Arnott and Hand "0878# claimed that their experimentswere of particular relevance to deposition from turbiditycurrents[ However\ Sanders and Friedman "0886# ques!tioned the relevance of these experiments to turbiditycurrents because the current was not carrying the sedi!ment in suspension[

Deformation of a 1[4 cm!diameter steel rod wasascribed to damage done by {turbidity currents| in theScripps submarine canyon\ o}shore California "Inman\Nordsrom + Flick\ 0865#[ However\ no evidence waspresented for bending of the steel rod by turbiditycurrents[ The deformed rod itself is evidence only forsome powerful force or event that caused the damage[In other words\ turbidity current is only one of severaloptions^ other possibilities are submarine slides\ sub!marine slumps\ submarine avalanches\ submarine debris~ows\ and even bottom currents[ In fact\ mass move!ments are quite common in submarine canyons"Shepard\ 0840#[ Slumping activity was reported fromthe Scripps submarine canyon "Dill\ 0853#\ and from theLa Jolla submarine canyon "Shepard\ 0868#[ However\attempts to generate turbidity currents at the head ofthe Scripps submarine canyon were unsuccessful "Dill\0853#[

The classic case of submarine telegraph cable breaks


by {turbidity currents| is the one associated with the 0818Grand Banks Earthquake "Heezen + Ewing\ 0841#[ Simi!lar to the case of the bent rod in the Scripps Canyon\there is no direct link between cable breaks and turbiditycurrents[ The presence of thin turbidite layers in this areais not the proof for cable breaks[ In fact\ Heezen andEwing "0841# recognized the possibility of cable breaksby slumps as well[ In discussing the breakage of the CableH in the Grand Banks area\ Hsu "0878# states\ {{Thisscenario suggests that the trans!Atlantic cable near thebase of the slope was not broken by a turbidity current\but by a high!speed\ sediment!gravity ~ow||[ Hsu "0878#suggests that the Cable H was broken by a debrisavalanche[ Sanders and Friedman "0886# ascribed cablebreaks in the Grand Banks area to lique_ed cohesionlesscoarse!particle ~ow\ a type of submarine avalanche[ Insupport of their hypothesis\ Sanders and Friedman"0886# pointed to the presence of small pebbles wedgedinto the frayed strands of the cable|s armor[ In my view\submarine slumps and avalanches are better candidatesfor breaking cables than turbidity currents because of thefast!moving solid masses of material involved in slumpsand avalanches[

Piper\ Shor and Hughes Clarke "0877# suggested thatdeep!sea gravel waves in the Grand Banks area are prod!ucts of bed load transport by turbidity currents\ anal!ogous to dune bed forms in subaerial rivers\ involvingtraction processes[ The implication is that these gravelwaves are composed of cross bedding^ however\ no coreinformation is available to prove the presence of crossbedding in these gravel waves[ Hsu "0878# proposed analternative\ debris avalanche\ origin for the gravel wavesin the Grand Banks area[ To my knowledge\ no onehas ever generated cross beds in ~ume experiments fromturbidity currents[

Hay et al[ "0871# reported the _rst remote acousticdetection of a modern {turbidity current| in the RupertInlet\ British Columbia[ The {turbidity current| event inthis case was detected using acoustic sounders operatingat 31[4\ 096\ and 199 kHz[ It is conceivable that this eventwas a turbidity current[ It is also possible that this eventwas a debris ~ow\ or a basal plastic ~ow with an over!riding Newtonian ~ow[ The problem with any acousticdata is that they cannot detect ~uid rheology or sediment!support mechanism in establishing the precise nature ofthe ~ow "i[e[\ turbidity current vs debris ~ow#[

Turbidity currents simply cannot exist without tur!bulence "Middleton\ 0882#[ However\ the term {turbiditycurrents| was used for non!turbulent "i[e[\ laminar state#~ows "McCave + Jones\ 0877#[ Similarly\ the term {lami!nar sheared layers|\ implying deposition from laminar"i[e[\ non!turbulent# ~ow\ was used for deposits of {tur!bidity currents| "Vrolijk + Southard\ 0886#[

Chikita "0878# used the term {turbidity currents| syn!onymously for subaerial river currents[ Turbidity currentis a subaqueous process and it is not analogous to suba!

erial river current "Table 0#[ Otherwise\ ~urial depositswould be misinterpreted as {{turbidities||[

Peira Cava and vicinity in SE France\ where the Annotsandstone is exposed\ served as the type locality for theformulation of the {Bouma Sequence|[ An important attri!bute of these deep!water sandsone beds is the claim thatvirtually every bed is described to show normal grading"Bouma\ 0851^ Pickering + Hilton\ 0887\ their _g[ 51\Log A#[ However\ these {normally graded| beds also showinverse grading at their base "e[g[\ Pickering+Hilton\ 0887\their _g[ 51\ Log A#\ ~oating armoured mud balls "e[g[\Stanley et al[\ 0867\ their _g[ 7[7D#\ and large ~oatingmudstone clasts in the middle "e[g[\ Pickering + Hilton\0887\ their _g[ 51\ Log A#[ Normal grading of a deep!watersandstone can be used as evidence for deposition fromsuspension settling of a turbidity current only if the sand!stone is devoid of inverse grading at the base\ armourdmud balls and ~oating mudstone clasts in the middle[ Thisis because inverse grading and ~oating armoured mud ballssuggest freezing of plastic debris ~ows[

Bouma "0851# did not include the presence of inversegrading\ ~oating armoured mud balls\ and ~oating mud!stone clasts as part of the vertical facies model of a tur!bidite "i[e[\ the Bouma Sequence# in the Annot Sandstone[As a result\ many of us emphasize only the presence of{normal grading|\ but ignore the importance of inversegrading and armoured mud balls while interpreting theorigin of the Annot Sandstone[ For example\ in spite oftheir observation of inverse grading\ armoured mud balls\and ~oating mudstone clasts in the Annot sandstone\Pickering and Hilton "0887# concluded that {{The Gresd| Annot Formation in the Peira Cava sub!basin is inter!preted to represent a base!of!slope sub!basin _ll withproximal!to!distal changes showing deposition of pre!dominantly sand!rich turbidites "italics mine# in the proxi!mal parts of the sub!basin\ and relatively sand!de_cientturbidites "italics mine# in the disal parts of the sub!basin||[ Pickering and Hilton "0887# also concluded thatmany basal beds of the Annot Sandstone are deposits ofhigh!concentration turbidity currents\ but they conceded\{{Of course\ the precise hydrodynamic conditions andsediment concentrations of high!concentration turbiditycurrents remains unresolved||[

Perhaps\ the single most important source of per!petuation of the turbidite paradigm is the biased way wedescribe {normal grading|\ which serves as the gateway toturbidite interpretation[ There are three types of normalgrading] "0# distibution grading in which all grain sizesdecline upwards over the entire bed "Middleton\ 0856#\"1# coarse!tail grading in which only the coarsest com!ponents decline upwards "Middleton\ 0856#\ and "2#delayed grading in which grain size declines gradually forthe most part of the bed\ but rapidly near the top of thebed "Walton\ 0845#[ All of them can be used as evidencefor turbidite deposition[ However\ none of them can beused if any one of them contain inverse grading at the


Fig[ 18[ Top] Schematic diagram showing development of simple normal grading by suspesion settling from a turbulent turbidity current[ Bottom]Schematic diagram showing development of inverse to normal grading by freezing and late!stage settling from a laminar debris ~ow[

base indicating plastic ~ows\ or contain ~oating mud!stone clasts in the middle indicating plastic ~ows\ orassociated with parallel lamination suggesting tractiondeposition[ Although inverse to normal grading is com!mon in deposits of debris ~ows "Fig[ 18#\ many ignorethe presence of inverse grading and emphasize only thenormal grading in arriving at the preferred turbiditeinterpretation[

Because the description and meaning of normal grad!ing varies from one worker to another\ it is not clear howmany of the published examples of {normal grading| trulyrepresent turbidite deposition "Fig[ 18#[ For example\describing a cross!bedded sandstone that is coarser at thebase than it is at the top as {graded| is not meaningful[ Incases like this\ {{[ [ [ the term graded has lost its originaldescriptive meaning so clearly set forth by Pettijohn andKuenen|| "Murphy + Schlanger\ 0851#[ I suggest that theconcept of {normal grading| should be reserved only todescribe deep!water intervals that do not contain cross!strati_cation\ horizontal strati_cation\ contortedbedding\ inverse grading\ ~oating mudstone clasts\ ~oat!ing quartz granules\ pockets of gravels\ etc[ Otherwise\deposits of slumps\ debris ~ows\ and bottom currentswould be misinterpreted as {turbidites|[

In sandstones showing divisions of the {BoumaSequence|\ it is more important to establish that the basaldivision "Ta# is normally graded than the entire {BoumaSequence| is normally graded[ Otherwise\ virtually everysandstone!shale sequence in the entire geologic record

could be described as {normally graded| on the assump!tion that the overlying shale represents the pelagic upperdivision "Te# of the {Bouma Sequence| and that the shaleis _ner grained than the underlying sandstone[

Finally\ even though Normark "0880# and Walker"0881a# have now abandoned their popular fan models\many petroleum geologists still use these models "e[g[\Coleman\ Swearingen + Breckon\ 0883^ McGee\ Bilinski\Gary\ Pfei}er + Sheimanan\ 0883^ Galloway\ 0887#[ So\the perpetuation of the turbidite paradigm goes on[ It isby design\ not by accident[

09[ A paradigm shift

In the 0869s and early 0879s\ I and my co!workersproposed ideal vertical facies models for _ne!graineddebris ~ows "Shanmugam + Benedict\ 0867#\ for _ne!grained turbidites "Stow + Shanmugam\ 0879#\ for therhythmic order of turbidites "Shanmugam\ 0879#\ and forturbidite fans "Shanmugam\ 0879#[ But my skepticismabout the dominance of turbidites in deep!water systemsand my perception of the inadequacy of facies modelsbegan to take root when I started describing cores andoutcrops worldwide in great detail "Fig[ 29#[ Prior tomy involvement in describing deep!water sequences forMobil\ which began in 0867\ I thought that most deep!water sands are turbidites and that they are commonlyorganized into channels and lobes in a submarine!fan


Fig[ 29[ Top] Graph showing the total thickness of intervals of deep!water core and outcrop that I have described since 0863\ when I beganmy Ph[D[ research at the University of Tennessee "Shanmugam\ 0867#[Bottom] Bars showing my changing perspectives of deep!water systemsat a scale of depositional units with my increasing exposure to deep!water sequences\ from one of order and simplicity in 0863 to one ofchaos and complexity in 0887[ Note that a major shift in my perspectiveoccurred in 0889 when I began describing cores from the North Seareservoirs\ composed primarily of deep!water massive sands[

setting\ re~ecting natural order[ Now\ I realize that deep!water systems are extremely complex and variable\re~ecting mostly chaos at the scale of depositional units"Fig[ 29#[ A major shift in my perspective of deep!watersystems occurred in 0889 when I began describing coresfrom the North Sea "Fig[ 29#[ This shift was due to myexposure to some of the most complicated deep!waterfacies that occur in the form of {massive| sands[ Aspectsof deep!water massive sands are addressed by Stow andJohansson "0888#[

Our understanding of depositional processes and sanddistribution in deep!water environments is still in itsinfancy[ No single facies model can adequately representall deep!water systems "Shanmugam\ 0889^ Mutti\ 0881#[Submarine fan studies are presently in a state of ~ux"Walker\ 0881a#[ The days of interpreting complex deep!water sequences as channels and lobes using fan modelsare over[ Sedimentologic and sequence!stratigraphic lin!eages of fan concepts dominated by lobes show that theirpopularity escalated in the 0869s and 0879s but declined

in the 0889s to a point of their abandonment "Fig[ 20#[The turbidite paradigm has come a full circle in the 0889s\completing a remarkable scienti_c journey set in motionin the 0849s[ Consequently\ we are not in any better statetoday in terms of deep!water facies models than we were49 years ago[

However\ we are in a better state today in terms ofavailable marine geological data\ core and outcrop stud!ies\ theoretical considerations\ and ~ume experiments[We have learned that deep!water systems are quite com!plex in terms of sea!~oor topography\ depositional pro!cesses\ geometries\ and stacking patterns[ We have alsolearned that no single facies model can possibly explainall variations in the complex deep!sea environments[

09[0[ Slope models for the 10st century

Mass transport processes "slides\ slumps\ sand ~ows\and debris ~ows# have been observed in modern oceans"e[g[\ Shepard\ 0840\ 0868^ Dill\ 0853\ 0855#^ however\convincing direct observations of turbidity currents inmodern oceans are lacking[ I _nd it ironic that thereare numerous deep!water facies models for deposits ofturbidity currents that we don|t observe\ but there are nofacies models for deposits of mass ~ows that we doobserve[ This is perhaps because of the simplicity of tur!bidity current concepts and submarine!fan models\ andthe historical association between turbidites and sheetgeometries[ It is true that basinal turbidites are sheet!likein geometry\ however\ these turbidite sands are com!monly thin bedded\ _ne grained\ and contain highamounts of mud[ In contrast\ slope sands of debris ~oworigin are thicker bedded\ coarser grained\ and containlower amounts of mud in comparison to turbidites[ Thecurrent trend in petroleum industry is to routinely applysubmarine!fan models\ developed for base!of slope set!tings with smooth sea ~oors\ to intraslope settings withhighly irregular sea ~oors\ such as in the Gulf of Mexico"Holman + Robertson\ 0883#[ However\ we need todevelop separate models for slopes emphasizing slopeprocesses and products[ The conventional wisdom thatslopes are areas of {bypassing| of sand is not valid in allcases[ Slopes are important future target areas wheremajor petroleum reservoirs are waiting to be found[ Stowand Faugeres "0887# aptly noted\ {{[ [ [ back to the slopeis the way forward into the next century||[

Although Galloway|s "0887# recent paper emphasizedthe importance of {slope| systems in petroleum explo!ration\ the paper is misleading because it uses confusingterminology\ abandoned concepts\ and selective facies[Galloway "0887# uses the term {slope| for base!of!slopesystems\ for the sake of brevity[ This is misleadingbecause slope systems and base!of!slope systems are quitedi}erent from one another in terms of] "0# sea!~oor top!ographies "irregular vs smooth#\ "1# slope gradients "highvs low#\ "2# gravity tectonics "common vs rare#\ "3# ero!


Fig[ 20[ Rise and fall of popularity of submarine!fan models in sedimentology and sequence stratigraphy during the past 49 years[

sional elements\ such as canyons and gullies "commonvs rare#\ "4# depositional processes "mass movements vsturbidity currents#\ and "5# openness of depositional sites"constrictive vs[ open#[ Galloway "0887# states\ {{sub!marine fans are the best known slope depositionalelements [ [ [|| and uses the Mississippi\ Amazon\ andIndus fans as examples of {slope| fans[ This is confusingbecause the bulk of major modern fans\ such as the Mis!sissippi\ are clearly developed on the basin ~oor\ not onthe slope[ Also\ the classic submarine!fan models withchannels and lobes "e[g[\ Mutti + Ricci Lucchi\ 0861#are meant for base!of!slope systems "where channels canspread out to form lobes on the vast open sea ~oors#\ notfor slope systems[ Because of the casual usgae of the terms{slope| and {fans|\ the geologic literature is saturated with{fans| in the intraslope areas of the Gulf of Mexico "e[g[\Weimer et al[\ 0883#[ The correct and precise usage ofthe terms {slope| and {fans| has major implications forestablishing paleogeography and predicting reservoirs[

Galloway "0887# promotes themounded\ sand!rich\ sup!rafan lobe concept[ This is outdated information becausethe suprafan lobe concept\ originally introduced by Nor!mark "0869\ 0867#\ has now been abandoned by Normark

"0880# himself[ Galloway "0887\ his _g[ 2# claims that wire!line log motifs can be useful in interpreting depositionalfacies[ This is misleading because di}erent depositionalfacies can generate similar log motifs\ and a single depo!sitional facies can generate a multitude of log motifs "Shan!mugam et al[\ 0883\ 0884a\ 0884b\ 0885#[ Galloway "0887#equates turbidite channels with ~uvial channels[ This ismisleading because turbidity currents and river currents arenot one and the same "Table 0#[

Galloway "0887\ his _g[ 6# discusses only the muddytypes of slides\ slumps\ and debris ~ows in his seven typesof slope facies[ This is selective because there are sandyslides "Fig[ 21#\ sandy slumps "Fig[ 21#\ and sandy debris~ows "Shanmugam et al[\ 0884a#[ Galloway "0887# dis!cusses only the muddy types of contourites "i[e[\ sedimentdrifts# in his seven types of slope facies[ This is selectivebecause there are also sandy contourites "Stow + Lovell\0868#[ Hydrocarbon!bearing sands of bottom current ori!gin "i[e[\ sandy contourites# have been reported fromthe Plio!Pleistocene intraslope basins of Gulf of Mexico"Shanmugam et al[\ 0882a#[ From petroleum industrypoint of view\ there is a need to understand the dis!tribution of sand in intraslope basins[


Fig[ 21[ Sheet!like geometry of ancient sandy submarine slides[ Ablation Point Formation\ Kimmeridgian Alexander Island\ Antarctica[ Note thelarge sandstone sheet with rotated:slumped edge "left#[ Person "arrow# 0[7 m tall[ From Macdonald et al[ "0882#[

By de_nition\ continental slopes represent the steepsea!~oor areas between shelf!slope break "about 199mwater depth# and slope!basin break "Fig[ 0#[ Althoughmost continental slopes have gradients of 2Ð5> slope\ withan average slope of 3> "Heezen\ Tharp + Ewing\ 0848#\actual slopes are much smaller "9[4Ð1>#[ In general "seePratson + Haxby\ 0885#\ slopes of active margins arerelatively steeper than those of passive margins[ Someslopes undergo extensive gravity tectonic deformation\which leads to development of diapirs and intraslopebasins with erosional features\ such as canyons and gul!lies "e[g[\ northern Gulf of Mexico\ Niger Delta#[ Depo!sition of thick sand bodies can occur in intraslope basins[

Future models should take into account the greatwealth of information available on modern and ancientslope processes and products\ such as\ ancient sandyslides "Fig[ 21#\ muddy slides\ slumps and debris ~ows[Debris ~ows can travel hundreds of kilometers on gentlegradients "Masson\ van Niel + Weaver\ 0887#[ On glaci!ated continental margins\ debris ~ows tend to develop_nger!like patterns "Elverhoi et al[\ 0886#[ These detailsare seldom included in popular deep!water models[

Ancient sandy slides in Antarctica exhibit sheet!likegeometries and can have abrupt terminations "Fig[ 21#[

Thick sandy slides that are encased in deep!water mudare likely to produce blocky wireline log motifs[ Slidesand bodies in Antarctica that are 0999m long and 49mthick may be recognized in seismic data[ Such sands arelikely candidates for developing stratigraphic trapsbecause of their isolated occurrence in deep!water mud[Ancient sandy slumps have been correlated throughouta distance of 07 km in Spain "Mutti\ 0881#[ Thus\ slides\slumps\ and debris ~ows are capable of traveling longdistances\ comprising sandy lithofacies\ and formingsheet!like geometries\ and should be included in standardmodels for petroleum exploration[

As a counterpart to turbidite dominated fan modelssuited for base!of!slope settings\ I o}er an alternativemodel that is representative of debris!~ow dominatedsystems suited for some slope\ and possibly for somebase!of!slope settings "Fig[ 22#[ Unlike submarine fanswith organized turbidite packages in channels and lobes"Mutti + Ricci Lucchi\ 0861#\ the proposed slope modeladvocates a complexity of deposits of debris ~ows andother processes "Fig[ 22#[ Debris!~ow dominated systemscan be broadly classi_ed into "0# non!channelized and "1#channelized types "Fig[ 22#[ Most deep!water reservoirsin the North Sea "Shanmugam et al[\ 0884a#\ Norwegian


Fig[ 22[ Proposed depositional model for non!channelized and channelized debris!~ow dominated systems\ which are common in slope and base!of!slope settings[ In non!channelized systems\ sandy debris ~ows are expected to occur downdip from sand!rich shelf "modi_ed after Shanmugam\0886a#[ In channelized systems\ sandy debris ~ows are expected to occur mainly within channels and at their terminus[ Although debris ~ows maygenerate lobate sand bodies\ they are not analogous to typical depositional lobes formed by classical turbidity currents in submarine fans "e[g[\ Mutti+ Ricci Lucchi\ 0861#[ Di}erent oil!water contacts "O:W# may be encountered in debris!~ow reservoirs because of their lateral discontinuity[However\ there are cases where debris!~ow reservoirs are sheet!like with good vertical and lateral connectivity caused by amalgamation of sand units[

Sea "Shanmugam et al[\ 0883#\ Gulf of Mexico "Shan!mugam + Zimbrick\ 0885#\ and o}shore Equatorial Gui!nea "Shanmugam et al[\ 0886b# are considered to be non!channelized type[ Channelized type includes certain inter!vals in the Edop Field in o}shore Nigeria "Shanmugamet al[\ 0884b#\ and the modern Mississippi Fan[ In thisslump and debris!~ow dominated slope model\ natureof shelf "sand rich vs mud rich#\ sea!~oor topography"smooth vs irregular# and depositional process "settling vsfreezing# tend to control sand distribution and geometry[Contrary to popular belief\ sandy debris ~ows can bethick\ areally extensive\ and excellent reservoirs "Shan!mugam + Zimbrick\ 0885#[ High frequency ~ows tend todevelop amalgamated debris!~ow deposits with lateralconnectivity and sheet!like geometry[

According to the model "Fig[ 22#\ amalgamated sandydebris ~ows may be predicted to occur downdip from asand!rich shelf[ Experimental studies of subaqueous

debris ~ows have shown that hydroplaning can dra!matically reduce the bed drag\ and thus increase headvelocity "Mohrig et al[\ 0887#[ This would explain whysubaqueous debris ~ows can travel faster and farther ongentle slopes than subaerial debris ~ows[

Although deposits of sandy debris ~ows are complex\they are capable of developing sheet!like geometries inthe rock record "Fig[ 23#[ The notion that all depositsof debris ~ows are discontinuous is ill founded becauseamalgamated deposits of debris ~ows can develop lat!erally connected sand bodies "Fig[ 23#[ In some ways\deposits of both turbidity currents and sandy debris ~owsare alike^ and in many ways\ they are di}erent from oneanother[

The conventional notion that debris!~ow reservoirs donot have good reservoir properties is not true because thelower Eocene sands of the Frigg Formation "Frigg Field\Norwegian North Sea#\ which are interpreted to be of


Fig[ 23[ Comparison of deposits of sandy turbidity currents and sandy debris ~ows[ Turbidity currents are shown to develop a submarine fan withchannels and lobes[ Debris ~ows are shown to develop isolated ~ows\ amalgamated ~ows\ and tongue or sheet ~ows in a non!channelized system^debris ~ow in a chanelized system is not shown[ Processes and deposits are shown as cross sectional views[ Note that debris ~ows are capable offorming sheet sands[

slump and debris ~ow origin\ exhibit extremely highporosities "16Ð21)# and permeabilities "899Ð3999 mD#"see Shanmugam et al[\ 0884a#[ Also\ experiments haveshown that sandy debris ~ows can deposit sands withonly a minute amount of clay "less than 0) by weight#[Although deposits of debris ~ows are chaotic at corescale\ they can organize themselves into an orderly\ there!fore predictable\ stacking pattern "Famakinwa + Shan!mugam\ 0887#[ In short\ the proposed debris!~owdominated slope model is in some respects better thanthe turbidite fan model[

00[ A critical perspective

During the past 49 years\ our misplaced a.nity tothe turbidity current concept has grown phenomenallybecause of its simplicity and predictability[ Consequently\we have deviated from using the single precise de_nitionof turbidity currents into using a multitude of de_nitionsthat allow us to classify any deep!water sand as somekind of turbidite[ As a result of the prevailing turbiditemind set\ we have manufactured a plethora of {turbidites|]"0# ~uxoturbidites\ "1# megaturbidites\ "2# seis!moturbidites\ "3# atypical turbidites\ "4# problematicaturbidites\ "5# high!density turbidites\ "6# unusual turbid!ites\ "7# ungraded turbidites\ "8# inversely graded turbid!ites\ and "09# base!missing turbidites[ None of these{turbidites| are the deposits of true turbidity currents^they are deposits of avalanches\ slumps\ debris ~ows\ and

bottom currents[ By this critique\ I do not suggest thatthere are no turbidites[ However\ I do advocate thatour interpretation of rocks must always be based onobservational evidence\ not on mind set and models[

What is troubling\ is that the de_nition of the term{turbidity current| has been changed almost 079> over theyears[ In the 0849s and 0859s\ turbidity currents wereconsidered to be ~ows with turbulent state\ waningvelocity\ and Newtonian rheology\ but in the 0879s and0889s\ turbidity currents are considered to be ~ows withlaminar state\ waxing velocity\ and plastic rheology[ Aconsequence of this reversal of de_nitions is that it allowsus to interpret deposits of debris ~ows as {turbidites|[ Inlight of the emerging new data from my studies thatrevealed the dominance of debris!~ow facies and theobsolescence of turbidite facies in many parts of theworld\ it is understandable as to why it is necessary torede_ne turbidity currents that includes debris ~ows[Only through such a rede_nition of {turbidity currents|\we could keep the turbidite paradigm alive in the 10stcentury[

Equally troubling\ is the use of the term {turbidite fan|loosely for any deep!water sand "Weimer et al[\ 0883#[This addictive practice\ which is prevalent in both pet!roleum industry and academia\ must stop[ My critiqueof the loose usage of the terms {turbidites| and {fans| isnot just a quibble over semantics^ the precise meaning ofthese terms has serious implications for ~uid dynamics\sandbody geometry\ reservoir predictability\ and econ!omics in petroleum industry[


In the 10st century\ when all is said and done\ data willdictate that a majority of {sandy turbidite fans| existsonly in facies models and in our minds\ not in the rockrecord[ Perhaps\ it is time to refocus our attention todescribing and interpreting rocks without the distractionof facies models[ In concluding this rather long andre~ective article\ I am optimistic that in the 10st century\a new paradigm for deep!water systems will emerge thatwill be more inclusive in terms of slope processes andproducts than just basinal turbidity currents and fanmodels[

Acknowledgements

I dedicate this paper to all those deep!water rocks thatquietly challenged and in~uenced my thinking during thepast 14 years[ I thank Dorrik Stow for inviting me topresent this paper as a keynote talk at Geoscience 0887Symposium entitled {Deep!Water Sedimentary Systems]Reservoirs and Source Rocks| held at Keele University\England\ in April 0887[ I also thank journal reviewers J[E[ Damuth and an anonymous reviewer for their criticalreview and exhaustive comments\ and journal editor Prof[D[ G[ Roberts for his helpful suggestions[ I thank R[ J[Moiola\ D[ W[ Kirkland\ S[ H[ Gabay\ and N[ Houghtonfor reviewing the manuscript\ Mark Lindsey for drafting\J[ E[ Krueger for managerial support\ and Mobil Tech!nology Company for granting permission to publish thispaper[ I wish to thank Mobil and O.ce of NavalResearch for funding experimental studies of sandydebris ~ows that were carried out at St[ Anthony FallsLaboratory of the University of Minnesota in Min!neapolis during 0885Ð0887\ and Je} Marr\ Peter Har}\and Gary Parker for providing me with data from sandydebris ~ow experiments and for their valuable discussion[I thank Jean Shanmugam for editorial comments\ andPam Luttrell "VP!NEPV# for absorbing the cost ofreprints[

References

Allen\ J[ R[ L[ "0862#[ Phase di}erences between bed con_gurationand ~ow in natural environments\ and their geological relevance[Sedimentology\ 19\ 212Ð218[

Allen\ J[ R[ L[ "0871#[ In Sedimentary structures\ their character andphysical basis\ vol[ 0 "pp[ 482#[ Amsterdam] Elsevier[

Anderton\ R[ "0874#[ Clastic facies models and facies analysis[ In P[ J[Brenchly\ P[ J[ Williams\ Sedimentology] recent developments andapplied aspects "pp[ 20Ð36#[ Oxford] Blackwell Scienti_c Publi!cations[

Arnott\ R[ W[ C[\ + Hand\ B[ M[ "0878#[ Bedforms\ primary structuresand grain fabric in the presence of suspended sediment rain[ Journalof Sedimentary Petrology\ 48\ 0951Ð0958[

Bagnold\ R[ A[ "0843#[ Experiments on a gravity free dispersion of largesolid spheres in a Newtonian ~uid under shear[ Proceedings of theRoyal Society of London "A#\ 114\ 38Ð52[

Bagnold\ R[ A[ "0845#[ The ~ow of cohesionless grains in ~uids[ Phil[Trans[ Royal Society of London\ Ser[\ A 138\ 124Ð186[

Bagnold\ R[ A[ "0851#[ Auto!suspension of transported sediment^ tur!bidity currents[ Royal Society of London Proceedings\ Series A\ 154\204Ð208[

Bailey\ E[ B[ "0825#[ Sedimentation in relation to tectonics[ GeologicalSociety of America Bulletin\ 36\ 0602Ð0615[

Belderson\ R[ H[\ + Kenyon\ N[ H[ "0865#[ Long!range sonar views ofsubmarine canyons[ Marine Geology\ 11\ M58ÐM63[

Bell\ H[ S[ "0831#[ Density currents as agents for transporting sediments[Journal of Geology\ 49\ 401Ð436[

Beverage\ J[ P[\ + Culbertson\ J[ K[ "0853#[ Hyperconcentration ofsuspended sediment[ American Society of Civil Engineers\ Pro!ceedings Journal of the Hydraulics Division\ 89 HY 5\ 006Ð017 Nov!ember[

Bouma\ A[ H[ "0851#[ In Sedimentology of some ~ysch deposits] a graphicapproach to facies interpretation "pp[ 057#[ Amsterdam] Elsevier[

Bouma\ A[ H[ "0861#[ Recent and ancient turbidites and contourites[Transactions*Gulf Coast Association of Geological Societies\ 11\194Ð110[

Bouma\ A[ H[ "0872#[ COMFAN[ Geo!Marine Letters\ 2\ 42Ð113 Nos[1\ 2\ 3[

Bouma\ A[ H[\ + Brouwer\ A[ "0853#[ In Turbidites] developments insedimentology 2 "pp[ 153#[ Amsterdam] Elsevier[

Bouma\ A[ H[\ + Coleman\ J[ M[ "0874#[ Peira Cava turbidite system\France[ In A[ H[ Bouma\ W[ R[ Normark\ + N[ E[ Barnes \ Sub!marine fans and related turbidite systems "pp[ 106Ð111#[ New York]Springer!Verlag[

Bouma\ A[ H[\ + Hollister\ C[ D[ "0862#[ Deep ocean basin sedi!mentation[ Proceedings of Society of Economic Paleontologists andMineralogists Paci_c Section Short Course\ Los Angeles\ California[G[ V[ Middleton\ + A[ H[ Bouma[ Turbidites and deep!water sedi!mentation\ 68Ð007[

Bouma\ A[ H[\ + Coleman\ J[ M[\ DSDP Leg 85 Shipboard Scientists"0874#[ Mississippi Fan] Leg 85 program and principal results[ InA[ H[ Bouma\ W[ R[ Normark\ + N[ E[ Barnes\ Submarine fans andrelated turbidite systems "pp[ 136Ð141#[ New York] Springer!Verlag[

Bramlette\ M[ N[\ + Bradley W[ H[ "0839#[ Geology and Biology ofNorth Atlantic deep!sea cores[ US Geological Survey\ Professionalpaper 085!A\ 0Ð23

Briggs\ G[\ + Cline\ L[ M[ "0856#[ Paleocurrents and source areas ofLate Paleozoic sediments of the Ouachita Mountains\ SoutheasternOklahoma[ Journal of Sedimentary Petrology\ 26\ 874Ð0999[

Bugge\ T[ "0872#[ Submarine slides on the Norwegian continentalmargin\ with special emphasis on the Storegga area[ IKU ContinentalShelf Institute Publication\ 009\ 041 Norway[

Bullard\ E[ "0864#[ The emergence of plate tectonics] a personal view[Annual Review of Earth and Planetary Sciences\ 2\ 0Ð29[

Campbell\ C[ S[ "0889#[ Rapid granular ~ows[ Annual Review of FluidMechanics\ 11\ 46Ð80[

Carter\ R[ M[ "0864#[ A discussion and classi_cation of subaqueousmass!transport with particular application to grain ~ow\ slurry ~ow\and ~uxoturbidites[ Earth!Science Reviews\ 00\ 034Ð066[

Casnedi\ R[ "0872#[ Hydrocarbon!bearing submarine fan system ofCellino Formation\ central Italy[ American Association of PetroleumGeologists Bulletin\ 56\ 248Ð269[

Chamberlain\ C[ K[ "0860#[ Bathymetry and paleoecology of Ouachitageosyncline of southeastern Oklahoma as determined from tracefossils[ American Association of Petroleum Geologists Bulletin\ 44\23Ð49[

Chikita\ K[ "0878#[ A _eld study on turbidity currents initiated fromspring runo}s[ Water Resources Research\ 14\ 146Ð160[

Chough\ S[ K[\ + Hesse\ R[ "0874#[ Contourites from the Eirik Ridge\South of Greenland[ Sedimentary Geology\ 30\ 074Ð088[

Clark\ J[ D[\ + Pickering\ K[ T[ "0885#[ In Submarine channels] processesand architecture "pp[ 120#[ London] Vallis Press[

Cline\ L[ M[ "0869#[ Sedimentary features of Late Paleozoic ~ysch\


Ouachita Mountains\ Oklahoma[ In J[ Lajoie\ Flysch sedimentologyin North America "pp[ 74Ð090#\ The Geological Association of Can!ada Special Paper\ Vol[ 6[

Coleman Jr\ J[ L[\ Swearingen\ G[ V[\ + Breckon\ C[ E[ "0883#[ TheJackfork Formation of Arkansas*a test for the Walker!Mutti!Vailmodels for deep!sea fan deposition] _eld guide book[ In Proceedingsof Geological Society of America South!Central Section Meeting\Little Rock\ Arkansas "pp[ 45#[

Coleman\ J[ M[\ + Garrison\ L[ E[ "0866#[ Geological aspects of marineslope stability\ northwestern Gulf of Mexico[ In A[ F[ Richards\Marine Geotechnology\ Marine Slope Stability\ Vol[ 1 "pp[ 8Ð33#[Crane\ Russak + Company\ Inc[\ New York] [

Cook\ H[ E[ "0868#[ Ancient continental slope sequences and their valuein understanding modern slope development[ In L[ J[ Doyle\ + O[H[ Pilkey\ Geology of continental slopes "pp[ 176Ð294#\ Society ofEconomic Paleontologists and Mineralogists Special Publication\Vol[ 16[

Costa J[E[\ Williams G[P[ "0873#[ Debris!~ow dynamics "videotape#[US Geological Survey Open File Report OF 73!9595

Coussot\ P[\ + Meunier\ M[ "0885#[ Recognition\ classi_cation andmechanical description of debris ~ows[ Earth!Science Reviews\ 39\198Ð116[

Cowan\ E[ A[\ Cai\ J[\ Powell\ R[ D[\ Seramur\ K[ C[\ + Spurgeon\ V[L[ "0887#[ Modern tidal rhythmites deposited in a deep!water estu!ary[ Geo!Marine Letters\ 07\ 39Ð37[

Crowell\ J[ C[ "0846#[ Origin of pebbly mudstones[ Geological Societyof America Bulletin\ 57\ 882Ð0998[

Cummins\ W[ A[ "0851#[ The greywacke problem[ Liverpool and Man!chester Geology Journal\ 2\ 40Ð61[

Curray\ J[ R[\ + Moore\ D[ G[ "0860#[ Growth of the Bengal deep!seafan and denudation in the Himalayas[ Geological Society of AmericaBulletin\ 71\ 452Ð461[

D|Agostino\ A[ E[\ + Jordan\ D[ W[ "0886#[ Reinterpretation of depo!sitional processes in a classic ~ysch sequence "Pennsylvanian Jack!fork Group#\ Ouachita Mountains\ Arkansas and Oklahoma]discussion[ American Association of Petroleum Geologists Bulletin\70\ 362Ð364[

Dalrymple\ R[ W[\ + Narbonne\ G[ M[ "0885#[ Continental slope sedi!mentation in the Sheepbed Formation "Neoproterozoic\ Win!dermere Supergroup#\ Mackenzie Mountains\ N[W[T[ CanadianJournal of Earth Science\ 22\ 737Ð751[

Daly\ R[ A[ "0825#[ Origin of submarine canyons[ American Journal ofScience\ 20\ 309Ð319[

Damuth\ J[ E[ "0864#[ Echo!character of the Western Equatorial Atlan!tic ~oor and its relationship to the dispersal and distribution ofterrigenous sediments[ Marine Geology\ 07\ 06Ð34[

Damuth\ J[ E[ "0866#[ Late Quaternary sedimentation in the WesternEquatorial Atlantic[ Bulletin Geological Society of America\ 77\ 752Ð767[

Damuth\ J[ E[\ + Embley\ R[ W[ "0870#[ Mass!transport processes onAmazon Cone] Western Equatorial Atlantic[ American Associationof Petroleum Geologists Bulletin\ 54\ 518Ð532[

Damuth\ J[ E[\ + Kumar\ N[ "0864#[ Amazon cone] morphology\ sedi!ments\ age\ and growth pattern[ Bulletin Geological Society of Amer!ica\ 75\ 584Ð609[

Damuth\ J[ E[\ Kolla\ V[\ Flood\ R[ D[\ Kowsmann\ R[ O[\ Monteiro\M[ C[\ Gorini\ M[ A[\ Palma\ J[ J[ C[\ + Belderson\ R[ H[ "0872#[Distributary channel meandering and bifurcation patterns on Ama!zon deep!sea fan as revealed by long!range side!scan sonar "GLO!RIA#[ Geology\ 00\ 83Ð87[

Damuth\ J[ E[\ Flood\ R[ D[\ Kowsmann\ R[ O[\ Gorini\ M[ A[\ +Belderson\ R[ H[ "0877#[ Anatomy and growth!pattern of Amazondeep!sea fan revealed by long!range side!scan sonar "GLORIA# andhigh!resolution seismic studies[ American Association of PetroleumGeologists Bulletin\ 61\ 774Ð800[

Dill\ R[ F[ "0853#[ Sedimentation and erosion in Scripps submarine

canyon head[ In R[ L[ Miller Marine geology "pp[ 12Ð30#[ London]Macmillan[

Dill\ R[ F[ "0855#[ Sand ~ows and sand falls[ In Fairbridge\ Encyclopediaof oceanography "pp[ 652Ð654#[ New York] Reinhold[

Dingle\ R[ V[ "0866#[ The anatomy of a large submarine slump on asheared continental margin "SE Africa#[ Geological Society of Lon!don Journal\ 023\ 182Ð209[

Doreen Jr\ J[ M[ "0840#[ Rubble bedding and graded bedding in TalaraFormation of northwestern Peru[ American Association of Pet!roleum Geologists Bulletin\ 24\ 0718Ð0738[

Dott Jr\ R[ H[ "0852#[ Dynamics of subaqueous gravity depositionalprocesses[ American Association of Petroleum Geologists Bulletin\36\ 093Ð017[

Drake\ C[ L[\ Ewing\ M[\ + Sutton\ G[ H[ "0848#[ Continental marginsand geosynclines] the east coast of North America\ north of CapeHatteras[ In L[ H[ Ahrens\ et al[\ Physics and Chemistry of the Earth\Vol[ 2 "pp[ 009Ð087#[ Oxford] Pergamon Press[

Dzulynski\ S[\ + Sanders\ J[ E[ "0851#[ Current marks on _rm mudbottoms[ Connecticut Academy of Arts and Science\ transactions\ 31\46Ð85[

Dzulynski\ S[\ + Walton\ E[ K[ "0854#[ In Sedimentary features of ~yschand greywackes "pp[ 163#[ Amsterdam] Elsevier[

Dzulynski\ S[\ Ksiazkiewicz\ M[\ + Kuenen\ Ph H[ "0848#[ Turbiditesin ~ysch of the Polish Carpathian Mountains[ Bulletin GeologicalSociety of America\ 69\ 0978Ð0007[

Elverhoi\ A[\ Norem\ H[\ Anderson\ E[ S[\ Dowdeswell\ J[ A[\ Fossen\I[\ Ha~idason\ H[\ Kenyon\ N[ H[\ Laberg\ J[ S[\ King\ E[ L[\ Sejrup\H[ P[\ Solheim\ A[\ + Vorren\ T[ "0886#[ On the origin and ~owbehavior of submarine slides on deep!sea fans along the Norwegian!Barents Sea continental margin[ Geo!Marine Letters\ 06\ 008Ð014[

Embley\ R[ W[ "0865#[ New evidence for occurrences of debris ~owdeposits in the deep sea[ Geology\ 3\ 260Ð263[

Embley\ R[ W[ "0879#[ The role of mass transport in the distributionand character of deep!ocean sediments with special reference to theNorth Atlantic[ Marine Geology\ 27\ 12Ð49[

Embley\ R[ W[\ + Jacobi\ R[ D[ "0866#[ Distributions and morphologyof large sediment slides and slumps on Atlantic continental margins[Marine Geotechnology\ 1\ 194Ð117[

Enos\ P[ "0858#[ Anatomy of a ~ysch[ Journal of Sedimentary Petrology\28\ 579Ð612[

Enos\ P[ "0866#[ Flow regimes in debris ~ow[ Sedimentology\ 13\ 022Ð031[

Ericson\ D[ B[\ Ewing\ W[ M[\ + Heezen\ B[ C[ "0841#[ Turbiditycurrents and sediments in North Atlantic[ American Association ofPetroleum Geoloìsts Bulletin\ 45\ 378Ð400[

Ewing\ M[\ Eittreim\ S[\ Ewing\ J[\ + Le Pichon\ X[ "0860#[ Sedimenttransport and distribution in the Argentine Basin\ 2[ Nepheloidlayer and processes of sedimentation[ Physics and Chemistry of theEarth 7\ 38Ð67[

Famakinwa\ S[ B[\ + Shanmugam\ G[ "0887#[ Orderliness in the midstof chaos] prediction of deep!water reservoir facies in a slump anddebris!~ow dominated system\ Equatorial Guinea[ 0887 AmericanAssociation of Petroleum Geologists Annual Convention ExtendedAbstracts\ 1\ A081[

Famakinwa\ S[ B[\ Shanmugam\ G[\ Hodgkinson\ R[ J[\ + Blundell\ L[C[ "0886#[ In Deep!water slump and debris!~ow dominated reservoirsof the Za_ro _eld area\ offshore Equatorial Guinea "pp[ A23#\ Amer!ican Association of Petroleum Geologists Annual Convention Of_cialProgram[

Fisher\ R[ V[ "0860#[ Features of coarse!grained\ high!concentration~uids and their deposits[ Journal of Sedimentary Petrology\ 30\ 805Ð816[

Fisher\ R[ V[ "0872#[ Flow transformations in sediment gravity ~ows[Geology\ 00\ 162Ð163[

Flood\ R[ D[\ + Hollister\ C[ D[ "0863#[ Current!controlled topographyon the continental margin o} the eastern United States[ In C[A[


Burke\ C[L[ Drake\ The Geology of Continental Margins "pp[ 086Ð194#[ New York] Springer!Verlag[

Flood\ R[ D[\ Manley\ P[\ Kowsmann\ R[ O[\ Appi\ C[ J[\ + Pirmez\ C["0880#[ Seismic facies and Late Quaternary growth of Amazonsubmarine fan[ In P[ Weimer\ + M[ H[ Link\ Seismic facies andsedimentary processes of submarine fans and turbidite systems "pp[304Ð322#[ New York] Springer!Verlag[

Flood R[ D[\ + Piper D[ J[ W[\ Shipboard Scienti_c Party "0884#Proceedings of the Ocean Drilling Program\ Initial Reports R[ D[Flood\ D[ J[ W[ Piper\ + A[ Klaus\ et al[\ Ocean Drilling Program]College Station\ Texas\ Texas A+M University\ 044\ 4Ð05

Forel\ F[ A[ "0776#[ Le ravin sous!lacustre de Rhone dans le lac Leman[Bulletin de la Societe Vaudoise Science Naturele\ 12\ 74Ð096[

Friedman\ G[ M[\ + Sanders\ J[ E[ "0886#[ Dispelling the myth of sea!~oor tranquility[ Geotimes\ 31\ 13Ð16[

Friedman\ G[ M[\ Sanders\ J[ E[\ + Kopaska!Merkel\ D[ C[ "0881#[ InPrinciples of sedimentary deposits] stratigraphy and sedimentology"pp[ 606#[ New York] McMillan Publishing Company[

Galay\ V[ "0876#[ In Erosion and sedimentation in the Nepal Himalaya"pp[ 09[00#[ Signapore] Ke}ord Press Pvt[ Ltd[

Galloway\ W[ E[ "0887#[ Siliciclastic slope and base!of!slope depo!sitional systems] component facies\ stratigraphic architecture\ andclassi_cation[ American Association of Petroleum Geologists Bull!etin\ 71\ 458Ð484[

Gee\ M[ J[ R[\ Masson\ D[ G[\ Watts\ A[ B[\ + Allen\ P[ A[ "0888#[ TheSaharan debris ~ow] an insight into the mechanics of long runoutsubmarine debris ~ows[ Sedimentology\ 35\ 206Ð224[

Gonthier\ E[ G[\ Faugeres\ J!C[\ + Stow\ D[ A[ V[ "0873#[ Contouritefacies of the Faro Drift\ Gulf of Cadiz[ In D[ A[ V[ Stow\ + D[ J[W[ Piper\ Fine!grained sediments] deep!water processes and facies"pp[ 164Ð181#\ Geological Society of London Special Publication\Vol[ 04[

Gorsline\ D[ S[\ + Emery\ K[ O[ "0848#[ Turbidity current depositsin Sand Pedro and Santa Monica basins o} southern California[Geological Society of America Bulletin\ 69\ 168Ð189[

Graham\ S[ A[\ Dickinson\ W[ R[\ + Ingersoll\ R[ V[ "0864#[ Himalayan!Bengal model for ~ysch dispersal in the Appalachian!OuachitaSystem[ Geological Society of America Bulletin\ 75\ 162Ð175[

Grover\ N[ C[\ + Howard\ C[ S[ "0827#[ The passage of turbid waterthrough Lake Mead[ American Society of Civil Engineers Trans!actions\ 092\ 619Ð689[

Hampton\ M[ A[ "0861#[ The role of subaqueous debris ~ows in gen!erating turbidity currents[ Journal of Sedimentary Petrology\ 31\664Ð682[

Hampton\ M[ A[ "0864#[ Competence of _ne!grained debris ~ows[ Jour!nal of Sedimentary Petrology\ 34\ 723Ð733[

Hampton\ M[ A[\ Lee\ H[ J[\ + Locat\ J[ "0885#[ Submarine landslides[Reviews of Geophysics\ 23\ 22Ð48[

Harms\ J[ C[\ + Fahnestock\ R[ K[ "0854#[ Strati_cation\ bed forms\and ~ow phenomena "with an example from the Rio Grande#[ InG[ V[ Middleton\ Primary sedimentary structures and their hyd!rodynamic interpretation "pp[ 73Ð004#\ Society of Economic Paleon!tologists and Mineralogists Special Publication\ Vol[ 01[

Harms J[ C[\ Southard J[ B[\ Spearing D[ R[\ + Walker R[ G[ "0864#[Depositional environments as interpreted from primary sedi!mentary structures and strati_cation sequences\ Lecture Notes forSociety of Economic Paleontologists and Mineralogists ShortCourse No[ 1\ Dallas\ Texas\ 050 pp

Hartley\ A[ J[\ + Prosser\ D[ J[ "0884#[ Reservoir characterization ofdeep!water clastic systems[ Geological Society of London SpecialPublication\ 83\ 145[

Hay\ A[\ Burling\ R[ W[\ + Murray\ J[ W[ "0871#[ Remote acousticdetection of a turbidity current surge[ Science\ 106\ 722Ð724[

Heezen\ B[ C[\ + Drake\ C[ L[ "0853#[ Grand Banks slump[ AmericanAssociation of Petroleum Geologists Bulletin\ 37\ 110Ð114[

Heezen\ B[ C[\ + Ewing\ M[ "0841#[ Turbidity currents and submarine

slumps\ and the 0818 Grand Banks earthquake[ American Journalof Science\ 149\ 738Ð762[

Heezen\ B[ C[\ + Hollister\ C[ D[ "0860#[ In The face of the deep "pp[548#[ New York] Oxford University Press[

Heezen\ B[ C[\ Hollister\ C[ D[\ + Ruddiman\ W[ F[ "0855#[ Shaping ofthe continental rise by deep geostrophic contour currents[ Science\041\ 491Ð497[

Heezen\ B[ C[\ Tharp\ M[\ + Ewing\ M[ "0848#[ The ~oors of the oceans]I[ The North Atlantic[ Geological Society of America Special Paper\54\ 011[

Heezen\ B[ C[\ Menzies\ R[ J[\ Schneider\ E[ D[\ Ewing\ W[ M[\ +Granelli\ N[ C[ "0853#[ Congo submarine canyon[ American Associ!ation of Petroleum Geologists Bulletin\ 37\ 0015Ð0038[

Heller\ P[\ + Dickinson\ W[ R[ "0874#[ Submarine ramp facies modelfor delta!fed\ sand!rich turbidite systems[ American Association ofPetroleum Geologists Bulletin\ 58\ 859Ð865[

Hendry\ H[ E[ "0862#[ Sedimentation of deep water conglomerates inLower Ordovician rocks of Quebec*composite bedding producedby liquefaction of sediment<[ Journal of Sedimentary Research\ 32\014Ð025[

Heritier\ F[ E[\ Lossel\ P[\ + Wathne\ E[ "0868#[ Frigg _eld!large sub!marine!fan trap in lower Eocene rocks of North Sea[ AmericanAssociation of Petroleum Geologists Bulletin\ 52\ 0888Ð1919[

Hesse\ R[ "0864#[ Turbiditic and non!turbiditic mudstone of Cretaceous~ysch sections of the East Alps and other basins[ Sedimentology\ 11\276Ð305[

Hiscott\ R[ N[\ + Aksu\ A[ E[ "0883#[ Submarine debris ~ows andcontinental slope evolution in front of quaternary ice sheets\ Ba.nBay\ Canadian Arctic[ American Association of Petroleum GeologistsBulletin\ 67\ 334Ð359[

Hiscott\ R[ N[\ Pickering\ K[ T[\ Bouma\ A[ H[\ Hand\ B[ M[\ Kneller\B[ C[\ Postma\ G[\ + Soh\ W[ "0886#[ Basin!~oor fans in the NorthSea] sequence stratigraphic models vs sedimentary facies] discussion[American Association of Petroleum Geologists Bulletin\ 70\ 551Ð554[

Hollister\ C[ D[ "0856#[ Sediment distribution and deep circulation in thewestern North Atlantic] Unpublished Ph[D[ dissertation\ New York\Columbia University\ 356 pp

Hollister\ C[ D[\ + Heezen\ B[ C[ "0861#[ Geologic e}ects of oceanbottom currents] western north Atlantic[ In A[ L[ Gordon\ Studiesin physical oceanography\ vol[ 1 "pp[ 26Ð55#[ New York] Gordonand Breach Science Publishers[

Hollister\ C[ D[\ + McCave\ I[ N[ "0873#[ Sedimentation under deep!sea storms[ Nature\ 298\ 119Ð114[

Holman\ W[\ + Robertson\ S[ S[ "0883#[ Field development and depo!sitional model\ and production performance of the turbiditic {J|Sands at prospect Bullwinkle\ Green Canyon 54 Field\ outer shelfGulf of Mexico[ Proceedings of Gulf Coast Section of Society ofEconomic Paleontologists and Mineralogists 04th Annual ResearchConference[ P[ Weimer\ A[ H[ Bouma\ + R[ F[ Perkins[ Submarinefans and turbidite systems\ 028Ð049[

Hsu\ K[ J[ "0848#[ Flute! and groove!casts in the Prealpine Flysch\Switzerland[ American Journal of Science\ 146\ 418Ð425[

Hsu\ K[ J[ "0866#[ Studies of Ventura Field\ California*I] faciesgeometry and genesis of lower Pliocene turbidites[ American Associ!ation of Petroleum Geologists Bulletin\ 50\ 026Ð057[

Hsu\ K[ J[ "0878#[ In Physical principles of sedimentology "pp[ 122#[New York] Springer!Verlag[

Hubert\ J[ F[ "0853#[ Textural evidence for deposition of many westernNorth Atlantic deep!sea sands by ocean!bottom currents ratherthan turbidity currents[ Journal of Geology\ 61\ 646Ð674[

Inman\ D[ L[\ Nordsrom\ C[ E[\ + Flick\ R[ E[ "0865#[ Currents insubmarine canyons] an air!sea!land interaction[ Annual Review ofFluid Mechanics\ 7\ 164Ð209[

Ingersoll\ R[ V[\ + Suczek\ C[ A[ "0868#[ Petrology and provenance ofNeogene sand from Nicobar and Bengal fans\ DSDP Sites 100 and107[ Journal of Sedimentary Petrology\ 38\ 0106Ð0117[


Iverson\ R[ M[ "0886#[ The physics of debris ~ows[ Reviews of Geophys!ics\ 24\ 134Ð185[

Jacobi\ R[ D[ "0865#[ Sediment slides on the northwestern continentalmargin of Africa[ Marine Geology\ 11\ 046Ð062[

Jacka\ A[ D[\ Beck\ R[ H[\ St Germain\ L[ C[\ + Harrison\ S[ C["0857#[ Permian deep!sea fans of the Delaware Mountain Group"Guadalupian#\ Delaware basin[ Society of Economic paleontologistsand Mineralogists Permian Basin Section Publication\ 57!00\ 38Ð89[

Johnson\ A[ M[ "0869#[ In Physical processes in geology "pp[ 466#[Freeman\ Cooper and Co[\ San Francisco] [

Johnson\ A[ M[ "0873#[ Debris ~ow[ In D[ Brunsden\ + D[ B[ Prior\Slope instability "pp[ 146Ð250#[ Chichester] John Wiley + Sons Ltd[

Johnson\ D[ "0827#[ The origin of submarine canyons[ Journal of Geo!morphology\ 0\ 000Ð239[

Kamola\ D[ L[\ + Van Wagoner\ J[ C[ "0884#[ Stratigraphy and faciesarchitecture of parasequences with examples from the Spring can!yon Member\ Blackhawk Formation\ Utah[ In J[ C[ Van Wagoner\+ G[ T[ Bertram\ Sequence stratigraphy of foreland basin deposits*outcrop and subsurface examples from the Cretaceous of North Amer!ica "pp[ 16Ð43#\ American Association of Petroleum GeologistsMemoir\ Vol[ 53[

Kelts\ K[\ + Arthur\ M[ A[ "0870#[ Turbidites after ten years of deep!sea drilling*wringing out the mop< In J[ E[ Warme\ R[ G[ Douglas\+ E[ L[ Winterer\ The deep sea drilling project] a decade of progress"pp[ 80Ð016#\ Society of Economic Paleontologists and MineralogistsSpecial Publication\ Vol[ 21[

Kenyon\ N[ H[ "0876#[ Mass!wasting features on the continental slopeof northwest Europe[ Marine Geology\ 63\ 46Ð66[

Klaus\ A[\ + Ledbetter\ M[ T[ "0877#[ Deep!sea sedimentary processesin the Argentine Basin revealed by high!resolution seismic records"2[4 kHz echograms#[ Deep!Sea Research\ 24\ 788Ð806[

Klein DeV\ G[ "0855#[ Dispersal and petrology of sandstones of Stan!leyÐJackfork boundary\ Ouachita fold belt\ Arkansas and Okla!homa[ American Association of Petroleum Geologists Bulletin\ 49\297Ð215[

Kneller\ B[ "0884#[ Beyond the turbidite paradigm] physical models fordeposition of turbidites and their implications for reservoir predic!tion[ In A[ J[ Hartley\ + D[ J[ Prosser\ Characterization of deep!marine clastic systems "pp[ 20Ð38#\ Geological Society Special Pub!lication\ Vol[ 83[

Komar\ P[ D[ "0860#[ Hydraulic jumps in turbidity currents[ GeologicalSociety of America Bulletin\ 71\ 0366Ð0370[

Kuenen\ Ph H[ "0826#[ Experiments in connection with Daly|s hypoth!esis on the formation of submarine canyons[ Leidse Geol[ Meded[\7\ 216Ð224[

Kuenen\ Ph H[ "0849#[ Turbidity currents of high density[ In Pro!ceedings of 07th International Geological Congress "0837#\ London"pp[ 33Ð41# Reports\ pt[7[

Kuenen\ Ph H[ "0842#[ Signi_cant features of graded bedding[ AmericanAssociation of Petroleum Geologists Bulletin\ 26\ 0933Ð0955[

Kuenen\ Ph H[ "0846#[ Sole markings of graded graywacke beds[ Jour!nal of Geology\ 54\ 120Ð147[

Kuenen\ Ph H[ "0847#[ Problems concerning source and transportationof ~ysch sediments[ Geologie en Mijnbouw\ 19\ 218Ð228[

Kuenen\ Ph H[ "0853#[ Deep!sea sands and ancient turbidites[ In A[ H[Bouma\ + A[ Brouwer\ Turbidites] developments in sedimentology 2"pp[ 2Ð22#[ Amsterdam] Elsevier[

Kuenen\ Ph H[ "0855#[ Matrix of turbidites] experimental approach[Sedimentology\ 6\ 156Ð186[

Kuenen\ Ph H[\ + Migliorini\ C[ I[ "0849#[ Turbidity currents as a causeof graded bedding[ Journal of Geology\ 47\ 80Ð016[

Kuhn\ T[ S[ "0869#[ In The structure of scienti_c revolutions "pp[ 109#[Chicago] University of Chicago Press[

Kvenvolden\ K[ A[ "0870#[ Organic geochemistry in the deep sea drillingproject[ In J[ E[ Warme\ R[ G[ Douglas\ + E[ L[ Winterer\ The deepsea drilling project] a decade of progress "pp[ 116Ð138#\ Society of

Economic Paleontologists and Mineralogists Special Publication\Vol[ 21[

Laughton\ A[ S[ "0870#[ The _rst decade of GLORIA[ Journal of Geo!physical Research\ 75\ 00400Ð00423[

Leeder\ M[ "0886#[ Book Reviews\ {The geology of ~uvial deposits*sedimentary facies\ basin analysis\ and petroleum geology| by A[ D[Miall[ Journal of Sedimentary Research\ 56\ 263Ð264[

Lewis\ K[ B[ "0860#[ Slumping on a continental slope inclined at 0>Ð3>[Sedimentology\ 05\ 86Ð009[

Loutit\ T[ S[\ Hardenbol\ J[\ + Vail\ P[ R[ "0877#[ Condensed sections]the key to age determination and correlation of continental marginsequences[ In C[ K[ Wilgus\ B[ S[ Hastings\ C[ G[ Kendall\ C[ St\H[ W[ Posamentier\ C[ A[ Ross\ + J[ C[ Van Wagoner\ Sea!levelchanges] an integrated approach "pp[ 072Ð102#\ Society of EconomicPaleontologists and Mineralogists Special Publication\ Vol[ 31[

Lovell\ J[ P[ B[\ + Stow\ D[ A[ V[ "0870#[ Identi_cation of ancient sandycontourites[ Geology\ 8\ 236Ð238[

Lowe\ D[ R[ "0864#[ Water escape structures in coarse!grained sedi!ments[ Sedimentology\ 11\ 046Ð193[

Lowe\ D[ R[ "0868#[ Sediment gravity ~ows] their classi_cation\ andsome problems of application to natural ~ows and deposits[ In L[J[ Doyle\ + O[ H[ Pilkey\ Geology of Continental Slopes "pp[ 64Ð71#\ Society of Economic Paleontologists and Mineralogists SpecialPublication\ Vol[ 16[

Lowe\ D[ R[ "0871#[ Sediment gravity ~ows] II*depositional modelswith special reference to the deposits of high!density turbiditycurrents[ Journal of Sedimentary Petrology\ 41\ 168Ð186[

Macdonald\ D[ I[ M[\ Moncrie}\ A[ C[ M[\ + Butterworth\ P[ J[ "0882#[Giant slide deposits from a Mesozoic fore!arc basin\ AlexanderIsland\ Antarctica[ Geology\ 10\ 0936Ð0949[

Maltman\ A[ "0883#[ In The geological deformation of sediments "pp[251#[ London] Chapman + Hall[

Marr\ J[\ Har} P[\ Shanmugam G[\ + Parker G[ "0886#[ Experiments onsubaqueous sandy debris ~ows[ Supplement to EOS Transactions\AGU Fall Meeting\ San Francisco\ 67\ Number 35\ F236

Masson\ D[ G[\ van Niel\ B[\ + Weaver\ P[ P[ E[ "0887#[ Flow processesand sediment deformation in the Canary Debris Flow on the NWAfrican continental rise[ Sedimentary Geology\ 009\ 052Ð068[

McBride\ E[ F[ "0851#[ Flysch and associated beds of the MartinsburgFormation "Ordovician#\ central Appalachians[ Journal of Sedi!mentary Petrology\ 21\ 28Ð80[

McCave\ I[ N[\ + Jones\ P[ N[ "0877#[ Deposition of ungraded mudsfrom high!density non!turbulent turbidity currents[ Nature\ 222\149Ð141[

McGee\ D[ T[\ Bilinski\ P[ W[\ Gary\ P[ S[\ Pfei}er\ D[ S[\ + Sheimanan\J[ L[ "0883#[ Geologic models and reservoir geometries of AugerField\ Deepwater Gulf of Mexico[ Proceedings of Gulf Coast Sectionof Society of Economic Paleontologists and Mineralogists 04thAnnual Research Conference[ P[ Weimer\ A[ H[ Bouma\ + R[ F[Perkins[ Submarine fans and turbidite systems\ 134Ð145[

Menard\ H[ W[ "0844#[ Deep!sea channels\ topography\ and sedi!mentation[ American Association of Petroleum Geologists Bulletin\28\ 125Ð144[

Miall\ A[ D[ "0874#[ Architectural!element analysis] a new method offacies analysis applied to ~uvial deposits[ Earth!Science Reviews\11\ 150Ð297[

Miall\ A[ D[ "0888#[ In defense of facies classi_cations and facies models[Journal of Sedimentary Research\ 58\ 1Ð4[

Middleton\ G[ V[ "0855#[ Experiments on density and turbidity cur!rents*I] motion of the head[ Canadian Journal of the Earth Science\2\ 412Ð435[

Middleton\ G[ V[ "0856#[ Experiments on density and turbidity cur!rents*III] deposition of sediment[ Canadian Journal of EarthSciences\ 3\ 364Ð494[

Middleton\ G[ V[ "0869#[ Experimental studies related to problems of~ysch sedimentation[ In J[ Lajoie\ Flysch sedimentology in North


America "pp[ 142Ð161#\ Geological Association of Canada SpecialPaper\ Vol[ 6[

Middleton\ G[ V[ "0882#[ Sediment deposition from turbidity currents[Annual Review Earth Planetary Sciences\ 10\ 78Ð003[

Middleton\ G[ V[\ + Bouma\ A[ H[ "0862#[ Turbidites and deep!watersedimentation[ In Proceedings of Society of Economic Paleon!tologists and Mineralogists Paci_c Section Short Course\ Anaheim\California "pp[ 046#[

Middleton\ G[ V[\ + Hampton\ M[ A[ "0862#[ Sediment gravity ~ows]mechanics of ~ow and deposition[ Proceedings of Paci_c SectionSociety of Economic Paleontologists and Mineralogists\ Los Angeles[G[ V[ Middleton\ + A[ H[ Bouma\ Turbidites and deep!water sedi!mentation\ 0Ð27[

Middleton\ G[ V[\ + Wilcock\ P[ R[ "0883#[ In Mechanics in the earthand environmental sciences "pp[ 348#[ Cambridge\ UK] CambridgeUniversity Press[

Milne\ J[ "0786#[ Suboceanic changes[ Geographical Journal 09\ 018Ð035\ 148Ð178

Mitchell\ A[ H[ G[\ + Reading\ H[ G[ "0858#[ Continental margins\geosynclines and ocean!~oor spreading[ Journal of Geology\ 66\518Ð535[

Mitchum Jr\ R[ M[ "0874#[ Seismic stratigraphic expression of sub!marine fans[ American Association of Petroleum Geologists Memoir\28\ 006Ð025[

Mitchum Jr\ R[ M[\ Sangree\ J[ B[\ Vail\ P[ R[\ + Wornardt\ W[ W["0889#[ Sequence stratigraphy in Late Cenozoic expanded sections\Gulf of Mexico[ In Proceedings of 00th Annual Research Conference\Gulf Coast Section of Society of Economic Paleontologists and Min!eralogists Foundation "pp[ 126Ð145#[

Mitchum Jr\ R[ M[\ Sangree J[ B[\ Vail P[ R[\ + Wornardt W[ W["0882#[ Recognizing sequences and systems tracts from well logs\seismic data\ and biostratigraphy] examples from Late Cenozoic ofthe Gulf of Mexico[ In P[ Weimer\ + H[ Posamentier\ Siliciclasticsequence stratigraphy] recent developments and applications\American Association of Petroleum Geologists Memoir\ 47\ pp[ 052Ð086

Mohrig\ D[\ Whipple\ K[ X[\ Hondzo\ M[\ Ellis\ C[\ + Parker\ G[ "0887#[Hydroplaning of subaqueous debris ~ows[ Geological Society ofAmerica Bulletin\ 009\ 276Ð283[

Moiola\ R[ J[\ + Shanmugam\ G[ "0873#[ Submarine fan sedimentation\Ouachita Mountains\ Arkansas and Oklahoma[ Trans[ Gulf CoastAssociation of Geologists Societies\ 23\ 064Ð071[

Moore\ G[ T[\ Starke\ G[ W[\ Bonham\ L[ C[\ + Woodbury\ H[ O["0867#[ Mississippi Fan\ Gulf of Mexico*physiography\ stra!tigraphy\ and sedimentological patterns[ In A[ H[ Bouma\ G[ T[Moore\ + J[ M[ Coleman\ Framework\ facies\ and oil!trappingcharacteristics of the upper continental margin\ vol[ 6 "pp[ 215#[American Association of Petroleum Geologists Studies in Geology[

Murphy\ M[ A[\ + Schlanger\ S[ O[ "0851#[ Sedimentary structures inllhas sao Sebastiao Formations "Cretaceous#\ Reconcavo Basin\Brazil[ American Association of Petroleum Geologists Bulletin\ 35\346Ð366[

Murray\ J[\ + Renard A[ F[ "0780#[ Report on deep!sea deposits basedon specimens collected during the voyage of H[M[S[ Challengerin the years 0761Ð0765\ Government Printer\ Challenger Reports\London\ 414 pp

Mutti\ E[ "0866#[ Distinctive thin!bedded turbidite facies and relateddepositional environments in the Eocene Hecho Group "sou!thcentral Pyrenees\ Spain#[ Sedimentology\ 13\ 096Ð020[

Mutti\ E[ "0874#[ Turbidite systems and their relations to depositionalsequences[ In G[ G[ Zu}a\ Provenance of arenites "pp[ 54Ð82#[ Dor!drecht] D[ Reidel Publishing Company[

Mutti\ E[ "0881#[ In Turbidite sandstones "pp[ 164#[ Milan\ Italy] AgipSpecial publication[

Mutti\ E[\ Ghibaudo G[ "0861#[ Un esempio di torbiditi di coniodesottomarina esterina] Le Arenarie di San Salvatore "Formationedi Bobbio\ Miocene# nell| Appennino di Piacenza[ Memorie dell|

Academia delle Scienze di Torino\ Classe di Scienze Fisiche\Mathematiche e Naturali\ Serie 3\ no[05\ 39 pp

Mutti\ E[\ + Normark\ W[ R[ "0876#[ Comparing examples of modernand ancient turbidite systems] problems and concepts[ In J[ R[Leggett\ + G[ G[ Zu}a\ Marine clastic sedimentology] concepts andcase studies "pp[ 0Ð26#[ London] G[ Graham and Trotman[

Mutti\ E[\ + Ricci\ Lucchi F[ "0861#[ Turbidites of the northern Apen!nines] introduction to facies analysis[ International Geology Review\19\ 014Ð055 "English translation by T[ H[ Nilsen\ 0867#[

Mutti\ E[\ Ricci Lucchi F[ "0864#[ Turbidite facies and facies associ!ations[ In] Examples of turbidite facies and facies associations fromselected formations of the northern Apennines[ Field Trip Guide!book A!00\ International Sedimentologic Congress IX\ Nice\ 10Ð25

Mutti\ E[\ Nilsen\ T[ H[\ + Ricci\ Lucchi F[ "0867#[ Outer fan depo!sitional lobes of the Laga Formation "Upper Miocene and LowerPliocene#\ east!central Italy[ In D[ J[ Stanley\ + G[ Kelling\ Sedi!mentation in submarine fans\ canyons\ and trenches "pp[ 109Ð112#[Stroudsburg\ Pennsylvania] Hutchinson and Ross[

Nardin\ T[ R[\ Hein\ F[ J[\ Gorsline\ D[ S[\ + Edwards\ B[ D[ "0868#[A review of mass movement processes\ sediment and acousticcharacteristics\ and contrasts in slope and base!of!slope systemsversus canyon!fan!basin ~oor systems[ In L[ J[ Doyle\ + O[ H[Pilkey\ Geology of continental slopes "pp[ 50Ð62#\ Economic Paleon!tologists and Mineralogists Special Publication\ Vol[ 16[

Natland\ M[ L[\ + Kuenen\ Ph H[ "0840#[ Sedimentary history of theVentura Basin\ California\ and the action of turbidity currents[ InJ[ L[ Hough\ Turbidity currents and the transportation of coarsesediments to deep water "pp[ 65Ð096#\ Society of Economic Paleon!tologists and Mineralogists Special Publication\ Vol[ 1[

Nelson\ C[H[ "0857#[ Marine geology of Astoria deep!sea fan] Unpub!lished Ph[D[ Dissertation] Corvallis\ Oregon\ Oregon State Univer!sity\ 176 pp

Nelson\ C[ H[\ + Nilsen T[ H[ "0873#[ Modern and ancient deep!sea fan sedimentation[ Society of Economic Paleontologists andMineralogists Short Course 03\ 393 pp

Nelson\ C[ H[\ Twichell\ D[ C[\ Schwab\ W[ C[\ Lee\ H[ J[\ + Kenyon\N[ H[ "0881#[ Upper Pleistocene turbidite sand beds and chaotic siltbeds in the channelized\ distal\ outer!fan lobes of the Mississippifan[ Geology\ 19\ 582Ð585[

Nemec\ W[ "0889#[ Aspects of sediment movement on steep delta slopes[In A[ Colella\ + D[ B[ Prior\ Coarse!grained deltas "pp[ 18Ð62#\International Association of Sedimentologists Special Publication\Vol[ 09[

Newman\ M[\ St Leeder\ M[ L[\ Woodru}\ A[ H[ W[\ + Hatton\ I[ R["0882#[ The geology of the Gryphon Field[ In J[ D[ Parker\ Pro!ceedings of the fourth Conference "pp[ 012Ð022#\ Petroleum geologyof northwest Europe[ London] Geological Society[

Nilsen\ T[ H[ "0879#[ Modern and ancient submarine fans] discussionof papers by R[ G[ Walker and W[ R[ Normark[ American Associ!ation of Petroleum Geologists Bulletin\ 53\ 0983Ð0001[

Norem\ H[\ Locat\ J[\ + Schieldrop\ B[ "0889#[ An approach to thephysics and the modeling of submarine ~owslides[ Marine Geo!technology\ 8\ 82Ð000[

Normark\ W[ R[ "0869#[ Growth patterns of deep sea fans[ AmericanAssociation of Petroleum Geologists Bulletin\ 43\ 1069Ð1084[

Normark\ W[ R[ "0867#[ Fan valleys\ channels\ and depositional lobeson modern submarine fans] characters for recognition of sandyturbidite environments[ American Association of Petroleum Geol!ogists Bulletin\ 51\ 801Ð820[

Normark\ W[ R[ "0880#[ Turbidite elements and the obsolescence ofthe suprafan concept[ Giornale di Geologia\ ser 2a\ 42:1\ 0Ð09[

Normark\ W[ R[\ + Piper\ D[ J[ W[ "0861#[ Sediment and growth patternof Navy deep!sea fan\ San Clemente Basin\ California borderland[Journal of Geology\ 79\ 087Ð112[

Normark\ W[ R[\ Moore\ J[ G[\ + Torresan\ M[ E[ "0882#[ Giantvolcano!related landslides and the development of the HawaiianIslands[ In W[ C[ Schwab\ H[ J[ Lee\ + D[ C[ Twichell\ Submarine


landslides] selected studies in the US Exclusive Economic Zone\ USGeoloìcal Survey Bulletin 1991\ pp[ 073Ð085

Normark\ W[ R[\ + Damuth J[ E[\ Leg 044[ Sedimentology Group"0886#[ Sedimentary facies and associated depositional elements ofthe Amazon Fan[ In R[ D[ Flood\ D[ J[ W[ Piper\ A[ Klaus\ + L[C[ Peterson\ Proceedings of the ocean drilling program\ scienti_cresults 044\ "pp[ 500Ð540#

Oakeshott\ J[ M[\ "0878#[ Aspects of depositional mechanisms of highconcentration sediment gravity ~ows[ Unpublished Ph[D[ thesis\Keele\ University of Keele\ 491 pp

O|Connell\ S[\ Normark\ W[ R[\ Ryan\ W[ B[ F[\ + Kenyon\ N[ H["0880#[ An entrenched thalweg channel on the Rhone Fan] interpret!ation from a SEABEAM and SEAMARC 0 survey[ In R[ H[Osborne\ From shoreline to abyss] contributions in marine geology inhonor of Francis Parker Shepard\ Society of Economic Paleon!tologists and Mineralogists Special Publication\ vol[ 35 "pp[ 148Ð169#[

Pequegnat\ W[ E[ "0861#[ A deep bottom current on the MississippiCone[ In L[ R[ A[ Capurro\ + J[ L[ Reid\ Contributions on thephysical oceanography of the Gulf of Mexico\ vol[ 1 "pp[ 54Ð76#[Houston] Gulf Publishing Co Texas A+M University Oceano!graphic Studies[

Pettijohn\ F[ J[ "0846#[ In Sedimentary rocks\ 1nd ed[ "pp[ 607#[ NewYork] Harper[

Phillips\ C[ J[\ + Davies\ T[ R[ H[ "0880#[ Determining rheologicalparameters of debris ~ow material[ Geomorphology\ 3\ 090Ð009[

Pickering\ K[ T[\ + Hilton\ V[ "0887#[ In Turbidite systems of SoutheastFrance "pp[ 118#[ London] Vallis Press[

Pickering\ K[ T[\ Hiscott\ R[ N[\ + Hein\ F[ J[ "0878#[ In Deep!marineenvironments "pp[ 305#[ London] Unwin Hyman[

Pickering\ K[\ Stow\ D[ A[ V[\ Watson\ M[\ + Hiscott\ R[ "0875#[Deep!water facies\ processes and models] a review and classi_cationscheme for modern and ancient sediments[ Earth!Science Reviews\12\ 64Ð063[

Pickering\ K[ T[\ Hiscott\ R[ N[\ Kenyon\ N[ H[\ Ricci\ Lucchi F[\+ Smith\ R[ D[ A[ "0884#[ In Atlas of deep water environments]architectural style in turbidite systems "pp[ 222#[ London] Chapmanand Hall[

Pierson\ T[ C[\ + Costa\ J[ E[ "0876#[ A rheologic classi_cation ofsubaerial sediment!water ~ows[ In J[ E[ Costa\ + G[ F[ Wieczorek\Debris ~ows:avalanches] process\ recognition\ and mitigation\ vol[ VII"pp[ 0Ð01#[[ Geological Society of America Reviews in EngineeringGeology[

Pilkey\ O[ H[\ Locker\ S[ D[\ + Cleary\ W[ J[ "0879#[ Comparison ofsand!layer geometry on ~at ~oors of 09 modern depositional basins[American Association of Petroleum Geologists Bulletin\ 53\ 730Ð745[

Piper\ D[ J[ W[ "0861#[ Turbidite origin of some laminated mudstones[Geological Magazine\ 097\ 004Ð015[

Piper\ D[ J[ W[ "0867#[ Turbidite muds and silts in deep!sea fans andabyssal plains[ In D[ J[ Stanley\ + G[ Kelling\ Sedimentation insubmarine fans\ canyons\ and trenches "pp[ 052Ð065#[ Stroudsburg\Pennsylvania] Hutchinson and Ross[

Piper\ D[ J[ W[\ Shor\ A[ N[\ + Hughes Clarke\ J[ E[ "0877#[ The 0818{Grand Banks| earthquake\ slump\ and turbidity current[ In H[ E[Clifton\ Sedimentologic consequences of convulsive geologic events"pp[ 66Ð81#\ Geological Society of America Special Paper\ 118[

Posamentier\ H[ W[\ + Erskine\ R[ D[ "0880#[ Seismic expression andrecognition criteria of ancient submarine fans[ In P[ Weimer\ + M[H[ Link\ Seismic facies and sedimentary processes of submarine fansand turbidite systems "pp[ 086Ð111#[ New York] Springer!Verlag[

Postma\ G[ "0875#[ Classi_cation of sediment gravity!~ow depositsbased on ~ow conditions during sedimentation[ Geology\ 03\ 180Ð183[

Postma\ G[\ Nemec\ W[\ + Kleinspehn\ K[ L[ "0877#[ Large ~oatingclasts in turbidites] a mechanism for their emplacement[ SedimentaryGeology\ 47\ 36Ð50[

Pratson\ L[ F[\ + Haxby\ W[ F[ "0885#[ What is the slope of the UScontinental slope< Geology\ 13\ 2Ð5[

Prior\ D[ B[\ Bornhold\ B[ D[\ + Johns\ M[ W[ "0873#[ Depositionalcharacteristics of a submarine debris ~ow[ Journal of Geology\ 81\696Ð616[

Qian\ Y[\ Yang\ W[\ Zhao\ W[\ Cheng\ X[\ Zhang\ L[\ + Xu\ W[ "0879#[Basic characteristics of ~ow with hyperconcentrations of sediment[In Proceedings of the International Symposium on River Sedi!mentation] Beijing "pp[ 064Ð073#[ Chinese Society of HydraulicEngineering[

Reading\ H[ G[\ + Richards\ M[ "0883#[ Turbidite systems in deep!waterbasin margins classi_ed by grain size and feeder system[ AmericanAssociation of Petroleum Geologists Bulletin\ 67\ 681Ð711[

Ricci\ Lucchi F[ "0864#[ Depositional cycles in two turbidite formationsof Northern Apennines "Italy#[ Journal of Sedimentary Petrology\34\ 2Ð32[

Rich\ J[ L[ "0849#[ Flow markings\ groovings\ and intrastratal crump!lings as criteria for recognition of slope deposits with illustrationsfrom Silurian rocks of Wales[ American Association of PetroleumGeologists Bulletin\ 23\ 606Ð630[

Rodine\ J[ D[\ + Johnson\ A[ M[ "0865#[ The ability of debris\ heavilyfreighted with coarse clastic material to ~ow on gentle slopes[ Sedi!mentology\ 12\ 102Ð123[

Runcorn\ S[ K[ "0851#[ Paleomagnetic studies for continental drift andits geophysical cause[ In S[ K[ Runcorn\ Continental drift "pp[ 0Ð39#[ New York] Academic[

Sakai\ T[\ + Masuda\ F[ "0885#[ Slope turbidite packets in a fore!arcbasin _ll sequence of the Plio!Pleistocene Kakegawa Group\ Japan]their formation and sea!level changes[ Sedimentary Geology\ 093\78Ð87[

Sanders\ J[ E[ "0852#[ Concepts of ~uid mechanics provided by primarysedimentary structures[ Journal of Sedimentary Petrology\ 22\ 062Ð068[

Sanders\ J[ E[ "0854#[ Primary sedimentary structures formed by tur!bidity currents and related resedimentation mechanisms[ In G[ V[Middleton\ Primary sedimentary structures and their hydrodynamicinterpretation "pp[ 081Ð108#\ Society of Economic Paleontologistsand Mineralogists Special Publication\ Vol[ 01[

Sanders\ J[ E[\ + Friedman\ G[ M[ "0886#[ History of petroleum explo!ration in turbidites and related deep!water deposits[ NortheasternGeology and Environmental Sciences\ 08"0:1#\ 56Ð091[

Sarg\ J[ F[\ + Skjold\ L[ J[ "0871#[ Stratigraphic traps in Paleocene sandsin the Balder area\ North Sea[ American Association of PetroleumGeologists Memoir\ 21\ 086Ð195[

Savage\ S[ B[ "0873#[ The mechanics of rapid granular ~ows[ Advancesin Applied Mechanics\ 13\ 178Ð255[

Schwab\ W[ C[\ Lee\ H[ J[\ Twichell\ D[ C[\ Locat\ J[\ Hans\ Nelson C[\McArthur\ W[ C[\ + Kenyon\ N[ H[ "0885#[ Sediment mass!~owprocesses on a depositional lobe\ outer Mississippi Fan[ Journal ofSedimentary Research\ 55\ 805Ð816[

Selley\ R[ C[ "0868#[ Dipmeter and log motifs in North Sea submarine!fan sands[ American Association of Petroleum Geologists Bulletin\52\ 894Ð806[

Shanmugam\ G[ "0867#[ The stratigraphy\ sedimentology\ and tectonicsof the Middle Ordovician Sevier Shale Basin in East Tennessee[Unpublished Ph[D[ dissertation\ The University of Tennessee\Knoxville\ 111 p

Shanmugam\ G[ "0879#[ Rhythms in deep sea\ _ne!grained turbiditeand debris!~ow sequences\ Middle Ordovician\ eastern Tennessee[Sedimentology\ 16\ 308Ð321[

Shanmugam\ G[ "0889#[ In G[ C[ Brown\ D[ S[ Gorsline\ + W[ J[Schweller\ Deep!marine facies models and the interrelationship ofdepositional components in time and space "pp[ 088Ð135#\ Deep!marine sedimentation] depositional models and case histories in hydro!carbon exploration and development[ San Francisco] Society of Econ!omic Paleontologists and Mineralogists "Society for SedimentaryGeology# Paci_c Section[


Shanmugam\ G[ "0881#[ Submarine canyons[ In Encyclopedia of Scienceand Technology\ 6th ed[ "pp[ 437Ð441#[ New York] McGraw!HillBook Company[

Shanmugam\ G[ "0885a#[ High!density turbidity currents] are theysandy debris ~ows< Journal of Sedimentary Research\ 55\ 1Ð09[

Shanmugam\ G[ "0885b#[ Perception vs reality in deep!water explo!ration[ World Oil\ 106\ 26Ð30[

Shanmugam\ G[ "0886a#[ The Bouma Sequence and the turbidite mindset[ Earth!Science Reviews\ 31\ 190Ð118[

Shanmugam\ G[ "0886b#[ Slope turbidite packets in a fore!arc basin _llsequence of the Plio!Pleistocene Kakegawa Group] their formationand sea!level changes*Discussion[ Sedimentary Geology\ 001\ 186Ð299[

Shanmugam\ G[ "0886c#[ Deep!water exploration] conceptual modelsand their uncertainties[ NAPE "Nigerian Association of PetroleumExplorationsists# Bulletin\ 01:90\ 00Ð17[

Shanmugam\ G[ "0887a#[ Dimensions and geometries of the com!ponents of deep!water systems[ Mobil Technology Company SpecialPublication\ Dallas\ 009[

Shanmugam\ G[ "0887b#[ Fifty years of turbidite paradigm "0837Ð0887#*keynote talk[ In Proceedings of Geoscience 87\ Keele Univer!sity\ organized by the Geological Society "pp[ 8#[

Shanmugam\ G[\ + Benedict III\ G[ L[ "0867#[ Fine!grained carbonatedebris ~ow\ Ordovician basin margin\ Southern Appalachians[ Jour!nal of Sedimentary Petrology\ 37\ 0122Ð0139[

Shanmugam\ G[\ + Benedict III\ G[ L[ "0872#[ Manganese distributionin the carbonate fraction of shallow and deep marine lithofacies\Middle Ordovician\ eastern Tennessee[ Sedimentary Geology\ 24\048Ð064[

Shanmugam\ G[\ + Walker\ K[ R[ "0867#[ Tectonic signi_cance of distalturbidites in the Middle Ordovician Blockhouse and lower sevierformations in east Tennessee[ American Journal Science\ 167\ 440Ð467[

Shanmugam\ G[\ + Moiola\ R[ J[ "0871#[ Eustatic control of turbiditesand winnowed turbidites[ Geology\ 09\ 120Ð124[

Shanmugam\ G[\ + Moiola\ R[ J[ "0873#[ Eustatic control of calciclasticturbidites[ Marine Geology\ 45\ 162Ð167[

Shanmugam\ G[\ + Moiola\ R[ J[ "0874#[ Submarine fan models] prob!lems and solutions[ In A[ H[ Bouma\ W[ R[ Normark\ + N[ E[Barnes\ Submarine fans and related turbidite systems "pp[ 18Ð23#[New York] Springer!Verlag[

Shanmugam\ G[\ + Moiola\ R[ J[ "0877#[ Submarine fans] Charac!teristics\ models\ classi_cation\ and reservoir potential[ Earth!Sci!ence Reviews\ 13\ 272Ð317[

Shanmugam\ G[\ + Moiola\ R[ J[ "0880#[ Types of submarine fanlobes] models and implications[ American Association of PetroleumGeologists Bulletin\ 64\ 045Ð068[

Shanmugam\ G[\ + Moiola\ R[ J[ "0883#[ An unconventional model forthe deep!water sandstones of the Jackfork Group "Pennsylvanian#\Ouachita Mountains\ Arkansas and Oklahoma[ Proceedings of GulfCoast Section of Society of Economic Paleontologists and Min!eralogists Foundation 04th Annual Research Conference\ Houston[ P[Weimer\ A[ H[ Bouma\ + R[ F[ Perkins\ Submarine fans and turbiditesystems\ 200Ð215[

Shanmugam\ G[\ + Moiola\ R[ J[ "0884#[ Reinterpretation of depo!sitional processes in a classic ~ysch sequence "Pennsylvanian Jack!fork Group#\ Ouachita Mountains\ Arkansas and Oklahoma[American Association of Petroleum Geologists Bulletin\ 68\ 561Ð584[

Shanmugam\ G[\ + Moiola\ R[ J[ "0886#[ Reinterpretation of depo!sitional processes in a classic ~ysch sequence "Pennsylvanian Jack!fork Group#\ Ouachita Mountains\ Arkansas and Oklahoma]Reply[ American Association of Petroleum Geologists Bulletin\ 70\365Ð380[

Shanmugam\ G[\ + Zimbrick\ G[ "0885#[ Sandy slump and sandy debris~ow facies in the Pliocene and Plaistocene of the Gulf of Mexico]implications for submarine fan models[ In Proceedings of American

Association of Petroleum Geologists International Congress and Exhi!bition\ Caracas\ Venezuela\ Of_cial Program "pp[ A34#[

Shanmugam\ G[\ Damuth\ J[ E[\ + Moiola\ R[ J[ "0874a#[ Is the turbiditefacies association scheme valid for interpreting ancient submarinefan environments< Geology\ 02\ 123Ð126[

Shanmugam\ G[\ Moiola\ R[ J[\ + Damuth\ J[ E[ "0874b#[ Eustaticcontrol of submarine fan development[ In A[ H[ Bouma\ W[ R[Normark\ + N[ E[ Barnes\ Submarine fans and related turbiditesystems "pp[ 12Ð17#[ New York] Springer!Verlag[

Shanmugam\ G[\ Moiola\ R[ J[\ + Sales\ J[ K[ "0877a#[ Duplex!likestructures in submarine fan channels\ Ouachita Mountains\ Arkan!sas[ Geology\ 05\ 118Ð121[

Shanmugam\ G[\ Spalding\ T[ D[\ + Rofheart\ D[ H[ "0882a#[ Processsedimentology and reservoir quality of deep!marine bottom!currentreworked sands "sandy contourites#] An example from the Gulf ofMexico[ American Association of Petroleum Geologists Bulletin\ 66\0130Ð0148[

Shanmugam\ G[\ Spalding\ T[ D[\ + Rofheart\ D[ H[ "0882b#[ Tractionstructures in deep!marine bottom!current reworked sands in thePliocene and Pleistocene\ Gulf of Mexico[ Geology\ 10\ 818Ð821[

Shanmugam\ G[\ Spalding\ T[ D[\ + Rofheart\ D[ H[ "0884c#[ Deep!marine bottom!current reworked sand "Pliocene and Pleistocene#\Ewing Bank 715 Field\ Gulf of Mexico[ Proceedings of Society ofEconomic Paleontologists and Mineralogists Core Workshop[ R[ D[Winn\ + J[ M[ Armentrout[ Turbidites and associted deep!waterfacies\ 19\ 14Ð43[

Shanmugam\ G[\ Bloch\ R[ B[\ Damuth\ + Hodgkinson\ R[ J[ "0886#[Basin!~oor fans in the North Sea] sequence stratigraphic modelsvs sedimentary facies] Reply[ American Association of PetroleumGeologists Bulletin\ 70\ 555Ð561[

Shanmugam\ G[\ Hermance\ W[ E[\ Olaifa\ J[ O[\ + Odior\ E[ G["0884b#[ Slump dominated upper slope reservoir facies\ Intra QuaIboe "Pliocene#\ Edop Field\ O}shore Nigeria "abs[#[ In Proceedingsof American Association of Petroleum Geologists Annual ConventionOf_cial Program "pp[ 77A#[

Shanmugam\ G[\ Moiola\ R[ J[\ McPherson\ J[ G[\ + O|Connell\ S["0877b#[ Comparison of turbidite facies associations in modernpassive!margin Mississippi Fan with ancient active!margin fans[Sedimentary Geology\ 47\ 52Ð66[

Shanmugam\ G[\ Lehtonen\ L[ R[\ Straume\ T[\ Syversten\ S[ E[\ Hodg!kinson\ R[ J[\ + Skibeli\ M[ "0883#[ Slump and debris ~ow domi!nated upper slope facies in the Cretaceous of the Norwegian andNorthern North Seas "50>Ð56>N#] implications for Sand distri!bution[ American Association of Petroleum Geologists Bulletin\ 67\809Ð826[

Shanmugam\ G[\ Bloch\ R[ B[\ Mitchell\ S[ M[\ Beamish\ G[ W[ J[\Hodgkinson\ R[ J[\ Damuth\ J[ E[\ Straume\ T[\ Syvertsen\ S[ E[\ +Shields\ K[ E[ "0884a#[ Basin!~oor fans in the North Sea] sequencestratigraphic models vs sedimentary facies[ American Association ofPetroleum Geologists Bulletin\ 68\ 366Ð401[

Shanmugam\ G[\ Bloch\ R[ B[\ Mitchell\ S[ M[\ Damuth\ J[ E[\ Beamish\G[ W[ J[\ Hodgkinson\ R[ J[\ Straume\ T[\ Syvertsen\ S[ E[\ +Shields\ K[ E[ "0885#[ Slump and debris!~ow dominated basin!~oor fans in the North Sea] an evaluation of conceptual sequence!stratigraphical models based on conventional core data[ In S[ P[Hesselbo\ + D[ N[ Parkinson\ Sequence Stratigraphy in BritishGeology "pp[ 034Ð064#\ Society Special Publication\ Vol[ 092[

Sheldon\ P[ G[ "0817#[ Some sedimentation conditions in Middle Port!age rocks[ American Journal of Science\ 04\ 132Ð141[

Shepard\ F[ P[ "0840#[ Mass movements in submarine canyon heads[Trans[ Am[ Gephys[ Union\ 21\ 394Ð307[

Shepard\ F[ P[ "0868#[ Currents in submarine canyons and other seavalleys[ In L[ J[ Doyle\ + O[ H[ Pilkey\ Geology of Continental Slopes"pp[ 74Ð83#\ Society of Economic Paleontologists and MineralogistsSpecial Publications\ Vol[ 16[

Shepard\ F[ P[\ + Dill\ R[ F[ "0855#[ In Submarine canyons and othersea valleys "pp[ 270#[ Chicago] Rand McNally + Co[


Shepard\ F[ P[\ + Marshall\ N[ F[ "0867#[ Currents in submarine can!yons and other sea valleys[ In D[ J[ Stanley\ + G[ Kelling\ Sedi!mentation in submarine fans\ canyons\ and trenches "pp[ 2Ð03#[Stroudsburg\ Pennsylvania] Hutchinson and Ross[

Shepard\ F[ P[\ Dill\ R[ F[\ + Von Rad\ U[ "0858#[ Physiography andsedimentary processes of La Jolla Submarine Fan and Fan!Valley\California[ American Association of Petroleum Geologists Bulletin\42\ 28Ð319[

Shepard\ F[ P[\ Revelle\ R[ R[\ + Dietz\ R[ S[ "0828#[ Ocean!bottomcurrents o} the California coast[ Science\ 78\ 377Ð378[

Shreve\ R[ L[ "0857#[ The Blackhawk Landslide[ Geological Society ofAmerica Special Paper 097\ 36 pp[

Shultz\ A[ W[ "0873#[ Subaerial debris!~ow deposition in the upperPaleozoic Cutler Formation\ Western Colorado[ Journal of Sedi!mentary Petrology\ 43\ 648Ð661[

Signorini\ R[ "0825#[ Determinazione del senso di sedimentazione deglistrati nelle formazione arenacea dell| Appennino settentrionale[Boll[ Soc[Geol[ Ital\ 44\ 148Ð156[

Simons\ D[ B[\ Richardson\ E[ V[\ + Nordin Jr\ C[ F[ "0854#[ Sedi!mentary structures generated by ~ow in alluvial channels[ In G[ V[Middleton\ Primary sedimentary structures and their hydrodynamicinterpretation "pp[ 23Ð41#\ Society of Economic Paleontologists andMineralogists Special Publication\ Vol[ 01[

Sohn\ Y[ K[ "0886#[ On traction!carpet sedimentation[ Journal of Sedi!mentary Research\ 56\ 491Ð498[

Southard\ J[ B[ "0864#[ Bed Con_gutations[ In J[ C[ Harms\ J[ B[Southard\ D[ R[ Spearing\ + R[ G[ Walker\ Depositional environ!ments as interpreted from primary sedimentary structures and strati!_cation sequences\ Lecture Notes for Society of EconomicPaleontologists and Mineralogists Short Course No[ 1\ Dallas\Texas\ p[ 4Ð32

Stanley\ D[ J[ "0852#[ Vertical petrographic variability in Annot Sand!stone turbidites[ Journal of Sedimentray Petrology\ 22\ 672Ð677[

Stanley\ D[ J[ "0877#[ Turbidites reworked by bottom currents] upperCretaceous examples from St[ Croix\ US Virgin Islands[ Smi!thsonian contribution[ Marine Science\ 11\ 68[

Stanley\ D[ J[\ + Kelling\ G[ "0867#[ In Sedimentation in submarinecanyons\ fans\ and trenches "pp[ 284#[ Dowden\ Hutchinson andRoss\ Inc[\ Stroudsburg\ Pennsylvania[

Stanley\ D[ J[\ + Moore\ G[ T[ "0872#[ The shelfbreak] critical interfaceon continental margins[ Society of Economic Paleontologists andMineralogists Special Publication\ 22\ 356[

Stanley\ D[ J[\ Palmer\ H[ D[\ + Dill\ R[ F[ "0867#[ Coarse sedimenttransport by mass ~ow and turbidity current processes anddownslope transformations in Annot Sandstone canyon!fan valleysystems[ In D[ J[ Stanley\ + G[ Kelling\ Sedimentation in submarinefans\ canyons\ and trenches "pp[ 74Ð004#[ Stroudsburg\ Pennsylvania]Hutchinson and Ross[

Stau}er\ P[ H[ "0856#[ Grain ~ow deposits and their implications\ SantaYnez Mountains\ California[ Journal of Sedimentary Petrology\ 26\376Ð497[

Stetson\ H[ C[ "0825#[ Geology and paleontology of the Georges Bankcanyons\ I[ Geology[ Geological Society of America Bulletin\ 36\228Ð255[

Stow\ D[ A[ V[ "0868#[ Distinguishing between _ne!grained turbiditesand contourites o} Nova Scotia[ Sedimentology\ 15\ 260Ð276[

Stow\ D[ A[ V[ "0874#[ Deep!sea clastics] where are we and where arewe going< In P[ J[ Brenchly\ + P[ J[ Williams\ Sedimentology] recentdevelopments and applied aspects "pp[ 56Ð83#[ Oxford] GeologicalSociety by Blackwell Scienti_c Publications[

Stow\ D[ A[ V[ "0888#[ Contourite Watch[ IGCP 321 Newsletter\ Issue0\ Southampton Oceanography Centre\ UK[ 7 p

Stow\ D[ A[ V[\ + Faugeres\ J!C[ "0887#[ Preface[ Sedimentary Geology\004\ 0[

Stow\ D[ A[ V[\ + Holbrook\ J[ A[ "0873#[ North Atlantic contourites]an overview[ In D[ A[ V[ Stow\ + D[ J[ W[ Piper\ Fine!grained

sediments] deep!water processes and facies "pp[ 134Ð145#\ GeologicalSociety Special Publication\ Vol[ 04[

Stow\ D[ A[ V[\ + Lovell\ J[ P[ B[ "0868#[ Contourites] their recognitionin modern and ancient sediments[ Earth!Science Reviews\ 03\ 140Ð180[

Stow\ D[ A[ V[\ + Piper D[ J[ W[ "0873#[ Fine!Grained Sediments\Deep!water processes and facies\ Geological Society Special Pub!lication\ 04\ 548

Stow\ D[ A[ V[\ + Shanmugam\ G[ "0879#[ Sequence of structures in_ne!grained turbidites] comparison of recent deep!sea and ancient~ysch sediments[ Sedimentary Geology\ 14\ 12Ð31[

Stow\ D[ A[ V[\ Faugeres\ J!C[\ Viana\ A[\ + Gonthier\ E[ "0887#[ Fossilcontourites] a critical review[ Sedimentary Geology\ 004\ 2Ð20[

Sullwold Jr\ H[ H[ "0859#[ Tarzana fan\ deep submarine fan of LateMiocene age\ Los Angeles County\ California[ American Associationof Petroleum Geologists Bulletin\ 33\ 322Ð346[

Sullwold Jr\ H[ H[ "0850#[ Turbidites in oil exploration[ In J[ A[ Pete!rson\ + J[ C[ Osmond\ Geometry of sandstone bodies "pp[ 52Ð70#[Oklahoma] Tulsa\ American Association of Petroleum Geologists[

Surlyk\ F[ "0876#[ Slope and deep shelf gully sandstones\ Upper Jurassic\East Greenland[ American Association of Petroleum Geologists Bull!etin\ 60\ 353Ð364[

Swarbrick\ R[ E[ "0880#[ Geological mounds and their seismicexpression[ In Proceedings of American Association of PetroleumGeologists Annual Convention "pp[ 103#[

Syvitski\ J[ P[ M[ "0874#[ Subaqueous slope failures within seismicallyactive fjords[ In G[ Vilks\ + J[ P[ M[ Syvitski\ Arctic Land!SeaInteractions\ Geological Survey of Canada\ Open File 0112\ pp[59Ð52

Ten Haaf\ E[ "0848#[ Properties and occurrence of turbidites[ Geologieen Mijnbouw\ 10\ 106Ð111[

The Learning Channel "0886#[ Landslides "videotape#[ Produced forthe Learning Channel "a cable television channel in the US# by theBBC Television\ London\ England

Tillman\ R[ W[\ + Ali\ S[ A[ "0871#[ Deep water canyons\ fans\ andfacies] models for stratigraphic trap exploration[ American Associ!ation of Petroleum Geologists Reprint Series\ 15\ 485[

Tucholke\ B[ E[\ Hollister\ C[ D[\ Biscaye\ P[ E[\ + Gardner\ W[ D["0874#[ Abyssal current character determined from sedimentbedforms on the Nova Scotian continental rise[ Marine Geology\55\ 32Ð46[

Twichell\ D[ C[\ + Roberts\ D[ G[ "0871#[ Morphology\ distribution\and development of submarine canyons in the United States Atlan!tic continental slope between Hudson and Baltimore Canyons[Geology\ 09\ 397Ð301[

Twichell\ D[ C[\ Schwab\ W[ C[\ + Kenyon\ N[ H[ "0884#[ Geometryof sandy deposits at the distal edge of the Mississippi Fan\ Gulf ofMexico[ In K[ T[ Pickering\ R[ N[ Hiscott\ N[ H[ Kenyon\ LucchiF[ Ricci\ + R[ D[ A[ Smith\ Atlas of deep water environments]architectural style in turbidite systems "pp[ 171Ð175#[ London] Chap!man + Hall[

Twichell\ D[ C[\ Schwab\ W[ C[\ Nelson\ C[ H[\ Kenyon\ N[ H[\ + Lee\H[ J[ "0881#[ Characteristics of a sandy depositional lobe on theouter Mississippi Fan from Sea MARC 0A sidescan sonar images[Geology\ 19\ 578Ð581[

Underwood\ M[ B[\ + Bachman\ S[ G[ "0871#[ Sedimentary faciesassociations within subduction complexes[ In J[ K[ Leggett\ Trench!forearc geology] sedimentation and tectonics on modern and ancientactive plate margins "pp[ 426Ð449#\ Geol[ Soc[ London Spec[ Publ[\Vol[ 09[

Unrug\ R[ "0852#[ Istebna Beds*a ~uxoturbidite formation in theCarpathian ~ysch[ Ann[ Geol[ Pologne\ 22\ 38Ð81[

Unrug\ R[ "0866#[ Ancient deep!sea traction currents deposits in theLgota Beds "Albian# of the Carpathian ~ysch] Rocznik PolskiegoTowarzystwa[ Geologicznego Annales de la Societe Geologique dePologne\ 36\ 244Ð269[

Vail\ P[ R[ "0876#[ Seismic!stratigraphy interpretation using sequence


stratigraphy[ Pt[ 0] seismic stratigraphy interpretation procedures[In A[ W[ Bally\ Atlas of seismic stratigraphy\ vol[ 16 "pp[ 0Ð09#[American Association of Petroleum Geologists Studies in Geology[

Vail\ P[ R[\ Mitchum Jr\ R[M[\ + Thompson S[ III "0866#[ Seismicstratigraphy and global changes of sea level\ part 3] global cycles ofrelative changes of sea level[ In C[ E[ Payton\ Seismic stra!tigraphyðpuemnŁapplications to hydrocarbon exploration\ AmericanAssociation of Petroleum Geologists Memoir 15\ pp[ 72Ð86

Vail\ P[ R[\ Audemard\ F[\ Bowman\ S[ A[\ Eisner\ P[ N[\ + Perez!Cruz\C[ "0880#[ The stratigraphic signatures of tectonics\ eustacy andsedimentology*an overview[ In G[ Einsele\ W[ Ricken\ + A[ Sei!lacher\ Cycles and events in stratigraphy "pp[ 507Ð548#[ Berlin] Spr!inger!Verlag[

Vallance\ J[ W[\ + Scott\ K[ M[ "0886#[ The Oseola mud~ow fromMount Rainier] sedimentology and hazard implications of a hugeclay!rich debris ~ow[ Geological Society of America Bulletin\ 098\032Ð052[

Valloni\ R[ "0874#[ Reading provenance from modern marine sands[ InG[ G[ Zu}a\ Provenance of arenites "pp[ 298Ð221#[ Dordrecht] D[Reidel Publishing Company[

Van der Lingen\ G[ J[ "0858#[ The turbidite problem[ New ZealandJournal of Geology and Geophysics\ 01\ 6Ð49[

Van Wagoner\ J[ C[\ Posamentier\ H[ W[\ Mitchum\ R[ M[\ Vail\ P[ R[\Sarg\ J[ F[\ Loutit\ T[ S[\ + Hardenbol\ J[ "0877#[ An overview ofthe fundamentals of sequence stratigraphy and key de_nitions[ InC[ K[ Wilgus\ B[ S[ Hastings\ C[ G[ C[ Kendall St\ H[ W[ Posa!mentier\ C[ A[ Ross\ + J[ C[ Van Wagoner\ Sea!level changes]an integrated approach\ Society of Economic Paleontologists andMineralogists Special Publication\ Vol[ 31 "pp[ 28Ð34#[

Varnes\ D[ J[ "0847#[ Landslide types and processes[ Landslide andEngineering Practice[ In E[ D[ Eckel\ Highway Research BoardSpecial Report 18\ 19Ð36

Vine\ F[ J[\ + Mathews\ D[ H[ "0852#[ Magnetic anomalies over oceanridges[ Nature\ 088\ 836Ð838[

Vrolijk\ P[ J[\ + Southard\ J[ B[ "0886#[ Experiments on rapid depositionof sand from high!velocity ~ows[ Geoscience Canada\ 13\ 34Ð43[

Walker R[G[ "0854#[ The origin and signi_cance of the internal sedi!mentary structures of turbidites[ Proceedings of the Yorkshire Geo!logical Society 24\ 0Ð21[

Walker\ R[ G[ "0862#[ Mopping up the turbidite mess[ In R[ N[ Gins!burg\ Evolving concepts in sedimentology "pp[ 0Ð26#[ Baltimore] TheJohns Hopkins University Press[

Walker\ R[ G[ "0864#[ Nested submarine!fan channels in the CapistranoFormation\ San Clemente\ California[ Geological Society of AmericaBulletin\ 75\ 804Ð813[

Walker\ R[ G[ "0867#[ Deep!water sandstone facies and ancient

submarine fans] models for exploration for stratigraphic traps[American Association of Petroleum Geologists Bulletin\ 51\821Ð855[

Walker\ R[ G[ "0873#[ General introduction] facies\ facies sequencesand facies models\ Walker R[G[\ 1nd ed[\ Facies models\ GeoscienceCanada\ Reprint Series\ 0\ 0Ð8

Walker\ R[ G[ "0881a#[ Turbidites and submarine fans[ In R[ G[ Walker\+ N[ P[ James\ Facies models] response to sea level change "pp[ 128Ð152#[ Geological Association of Canada[

Walker\ R[ G[ "0881b#[ Facies\ facies models\ and modern stratigraphicconcepts[ In R[ G[ Walker\ + N[ P[ James\ Facies models] responseto sea level change "pp[ 0Ð03#[ Geological Association of Canada[

Walker\ J[ R[\ + Massingill\ J[ V[ "0869#[ Slump features on the Mis!sissippi Fan\ northeastern Gulf of Mexico[ Geological Society ofAmerica Bulletin\ 70\ 2090Ð2097[

Wallis\ G[ B[ "0858#[ In One!dimensional two!phase ~ow "pp[ 397#[ NewYork] McGraw!Hill[

Walton\ E[ K[ "0845#[ Limitation of graded bedding and alternativecriteria of upward sequences in rocks of the Southern Uplands[Transactions of the Edinburgh Geological Society\ 05\ 151Ð160[

Walton\ E[ K[ "0856#[ The sequence of internal structures in turbidites[Scottish Journal of Geology\ 2\ 295Ð206[

Warme\ J[ E[\ Douglas\ R[ G[\ + Winterer\ E[ L[ "0870#[ The deep seadrilling project] a decade of progress[ Society of Economic Paleon!tologists and Mineralogists Special Publication\ 21\ 453[

Wells\ N[ A[ "0887#[ Clastic Sedimentology*Deep Sea[ Geotimes\ 32\20Ð21[

Weimer\ P[ "0889#[ Sequence stratigraphy\ facies geometries\ and depo!sitional history of the Mississippi Fan\ Gulf of Mexico[ AmericanAssociation of Petroleum Geologists Bulletin\ 63\ 314Ð342[

Weimer\ P[\ + Link\ M[ H[ "0880#[ Seismic facies and sedimentaryprocesses of submarine fans and turbidite systems "pp[ 336#[ NewYork] Springer!Verlag[

Weimer\ P[\ Bouma\ A[ H[\ + Perkins\ R[ F[ "0883#[ Submarine fans andturbidite systems[ In Proceedings of Gulf Coast Section of Society ofEconomic Paleontologists and Mineralogists 04th Annual ResearchConference\ Houston "pp[ 339#[

Whitaker McD\ J[ H[ "0863#[ Ancient submarine canyons and fanvalleys[ In R[ H[ Dott Jr\ + R[ H[ Shaver\ Modern and ancientgeosynclinal sedimentation "pp[ 095Ð014#\ Soc[ Econ[ Paleont[ andMineral[ Special Publ[\ Vol[ 08[

Woodcock\ N[ H[ "0868#[ Sizes of submarine slides and their signi_!cance[ Journal of Structural Geology\ 0\ 026Ð031[

Wust\ G[ "0825#[ Schichtung und Zikulation des Atlantischen Ozeans[Das Bodenwasser und die Stratosphare] Duetschen AtlantischenExpedition[ Tiefsee[ Geologische Rundschhau\ 36\ 076Ð084[

Zhenzhong\ Gao\ et al[ "0887#[ In Deep!water traction current deposits"pp[ 151#[ Beijing\ and VSP\ The Netherlands] Sciences Press[

Documents

50 Years of the Turbidite Paradigm (Shanmugam, 2000)