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Petroleum Systems of Divergent Continental Margin Basins

25th Annual Gulf Coast Section SEPM FoundationBob F. Perkins Research Conference

2005

Program and Abstracts

Houston Marriott WestchaseHouston, Texas

December 4–7, 2005

Edited by

Paul J. Post, Norman C. Rosen,Donald L. Olson, Stephen L. Palmes,

Kevin T. Lyons, and Geoffrey B. Newton

ii Program and Abstracts

Copyright © 2005 by theGulf Coast Section SEPM Foundation

www.gcssepm.org

Published December 2005

Expenses for this Conference have been subsidized by a very generous grant from Statoil.

http://www.gcssepm.org/

25th Annual Gulf Coast Section SEPM Foundation Bob F. Perkins Research Conference—2005 iii

Foreword

Let’s start with the facts. I had a really nice,normal (for me) foreword written for the GCSSEPM25th Annual Bob F. Perkins Research Conference,Petroleum Systems of Divergent Continental MarginBasins CD. I was going to e-mail it to Norm the lastweek of August and beat all the deadlines: so muchfor the best of intentions. As you may know, I work forMinerals Management Service in New Orleans,although we are actually in Jefferson Parish, which isa piece of bureaucratic slight-of-hand.

When I left work Thursday, Katrina was forecastto make landfall around Tallahassee, Florida.Papers like Roberto Fainstein’s final on CD were onmy worktable at MMS ready to courier to Norm whenI received a few more; others, like Gabor Tari’ssecond submission on the proto-Pannonian basin, Iplanned to edit the next week. Something about bestintentions and plans seems to stick in my mind.Hurricane Katrina made landfall the followingMonday, August 29. Katrina was one of the strongeststorms to impact the coast of the United Statesduring the last 100 years. With sustained windsduring landfall of 140 mph (a strong category 4hurricane on the Saffir-Simpson scale) and minimumcentral pressure the third lowest on record at landfall(920 mb), Katrina caused widespread devastationalong the central Gulf Coast states of the US. Citiessuch as New Orleans, LA; Mobile, AL; Waveland,Biloxi, Gulfport, and Pascagoula MS bore the bruntof Katrina's force. It did serious damage to the 10-story building where MMS has nine floors. Of course,you would have had to be living in a cave to not knowor have seen pictures of the devastation. We lostelectricity, at 5:20 AM that morning, and telephoneconnections after 8:00 PM.

We live just over 35 miles north of New Orleans;north of I-12 and any flood danger amidst pine treeswith diameters of 1.5-2’ and more than 50’ high. Thewestern eyewall of Katrina passed nearly over us.We had sustained winds in excess of 100 mph formore than 4 hours and gusts greater than 140.Rather than go into the effects on us, the living in acave comment was appropriate. We had no powerfor nine days, occasional telephone service, couldnot drink the water, showered in the dog runs; wewon’t go into the servicing of other bodily functions.For those of us who did not evacuate it was a kind oflike living like a caveman: air-conditioningGOOOOD: Internet NIIIICE.

Many of my friends and colleagues lost theirhomes and most of their possessions. Theyscattered like leaves in, yes, a hurricane. When we

got phone service back, for the first time theThursday after Katrina, my first call was to mymother, my second was to Norm. Of course, thephone was only up for about 5 hours, we then lost itagain for about a week. It came back for another 4hours. Finally, after about 19 days, our telephoneservice generally stayed up. As Norm said, you havelived through a life-changing event. It was also anevent that taught a lot of us what is really importantin life and what is just not worth considering.

I did not have access to my files on the MMSnetwork. Had I known that the southeast Louisianaarea was suddenly the landfall target, I would havetaken my files home on my portable hard drive. Stillanother technological opportunity missed. Finally, inlate September, when our electricity and phones,and those of our ISP were all up, I began trying tocontact the authors who contributed papers to thisconference. I was able to get in touch with many ofthem via e-mail. Others, I was able to contact viathird parties, such as Jason Carneiro, a colleague ofRicardo Bedergal, who forwarded my e-mails toRenato Darros, Marta Guerra and Webster Mohriak.Without the help of people like Jason, pulling thisresearch conference together would not have beenpossible.

With the devastation of hurricanes Katrina andRita as a backdrop, and a feel for what is trulyimportant, I would like to thank the management ofMMS Resource Evaluation; Dave Marin, DavidCooke, and Abdul Khan for allowing me the time toput this conference together, contact authors, authorand co-author papers and edit papers. The quality ofthis conference is a tribute to the input of manypeople. However, I want to especially thank WebsterMohriak and Dave Brown. Their guidance regardingauthors/researchers to solicit for papers and inWebster’s case his direct solicitation of so manyquality papers from his Brazilian colleagues wasinvaluable. I also want to extend my sincerestappreciation to Don Olson, who has the cubicle nextto mine, and who with me edited most of themanuscripts. Don has the unique ability to determineif things make sense to someone without thetechnical expertise in areas often assumed byauthors. The clarity and readability of many of thepapers in this volume is a tribute to Don. In addition,MMS management allowed my colleagues, StephenPalmes and Kevin Lyons, time to review and editpapers. Geoff Newton, a former Texaco colleaguealso edited papers. My co-chairs; Bill Bosworth,Marita Bradshaw, Tony Doré, Garry Karner, Webster

iv Program and Abstracts

Mohriak, and Mike Roberts; and program advisorycommittee of Al Danforth, Carl Fiduk, Geoff Newton,Stephen Palmes, and Gábor Tari provided insightand comments that helped shape this researchconference, set its tone and program. Mark Rowan isone of the people I trust most to give me advice. Hereviewed the abstracts and re-worked the programwith the themes and speaker order used in thisconference. His knowledge of speakers, theirbackgrounds and their expertise have beeninvaluable. The flow of the program is a tribute to hisskill. Of course, Norm Rosen, one of my oldestfriends deserves a lot of credit for keeping metogether during the dark days of trying to solicitpapers, get the authors to commit, provide their

papers, and be a part of this conference. One thingNorm did not do, was to help me herd cats. That iswhat this organizing and co-coordinating one of theseconferences is really all about.

To those of you who took the time to read this mythanks. I hope you appreciate the science, insight,and quality of the papers in this CD. They are atribute to their authors, their companies who gavethem the permission and support to provide thepapers, the partners who granted their permission,and the various data owners who allowed their datato be used. Hopefully, the papers presented addressmany of the exploration issues we sought to clarifywhen we conceived this conference.

Paul Post

And now a word from the publisher: This isthe first time I have decided to add some words tothe editor’s comment. May you live in interestingtimes does not come close to describing the pastmonth. Everyone is aware as to how Katrina and Ritaaffected Louisiana, an area (believe it or not) that Iregard as a second home. My wife and I went toschool at LSU (Geaux Tigers!), our daughter wasborn in N’awlins, and some of our best friends inN’awlins were Cajuns. We lived through Betsy,Hilda, Camille, a glancing blow from Fredrick, Celia,and God knows how many other tropical storms Ihave forgotten. My first well proposal was in BayouPenchant North and it came in for some strangereason! The second proposal that I helped to writewas in Horse Shoe Bayou and I cannot explain why,it came in also! These are some of the reasons as

to why the region means so much to me. May someBeing, Force, or God protect this land from thepoliticians.

During the trying times Paul has describedabove, one of his main concerns has been thisconference. It is no joke that his second phone callwas to me. Paul’s main concern was that theconference would not happen because so muchmaterial was stuck in the Metairie office. Although Itried to explain to Paul that there really are somethings more important than this conference, he reallydid not pay attention to me. I can honestly say thatnot even a category 4 hurricane can stop Paul Postfrom his appointed rounds. For this reason, usingwhatever influence I have, this conference isdedicated to Paul.

25th Annual Gulf Coast Section SEPM Foundation Bob F. Perkins Research Conference—2005 v

GCSSEPM Foundation

Trustees and Executive Director

Michael J. Styzen (Chief Trustee)Shell E&P Deepwater ServicesNew Orleans, Louisiana

Rashel N. RosenMicropaleontological ConsultantHouston, Texas

Paul WeimerUniversity of ColoradoBoulder, Colorado

Michael J. NaultApplied BiostratigraphixHouston, Texas

Norman C. Rosen, Executive DirectorNCR & AssociatesHouston, Texas

Executive Council

PresidentRobert LoucksBureau of Economic GeologyAustin, Texas

President ElectLesli WoodBureau of Economic GeologyAustin, Texas

Vice PresidentKevin SchofieldBHP Billiton Petroleum (Americas) Inc.Houston, Texas

SecretaryLana CzerniakowskiConocoPhillipsHouston, Texas

TreasurerRamón TreviñoBureau of Economic GeologyAustin, Texas

Past-PresidentJory A. PachtSeis-Strat ServicesHouston, Texas

Audio-Visual and Poster Committee

Michael J. NaultApplied Biostratigraphix

Jerri FillonEarth Studies Associates

Arden CallenderApplied Biostratigraphix

Program Advisory Committee Co-Chairs

Paul J. PostMinerals Management Service

William BosworthMarathon

Marita BradshawGeoscience Australia

A.G. (Tony) DoréStatoil

Webster MohriakPetrobrasMike RobertsChevronTexaco

Program Advisory Committee

Al DanforthConsultantGeoffrey NewtonConsultantGábor TariVanco Energy Company

Joseph FidukCGG

Stephen PalmesMinerals Management Service

vi Program and Abstracts

Contributors to the GCSSEPM Foundation

Sponsorship Categories

Please accept an invitation from the GCSSEPM Section and Foundation to support Geological andGeophysical Staff and Graduate Student Education in Advanced Applications of Geological Research toPractical Problems of Exploration, Production, and Development Geology.

The GCSSEPM Foundation is not part of the SEPM Foundation. In order to keep our conferences priced ata low level and to provide funding for university staff projects and graduate scholarships, we must haveindustry support. The GCSSEPM Foundation provides several categories of sponsorship. In addition, you mayspecify, if you wish, that your donation be applied to Staff support, Graduate support, or support of ourConferences. Please take a moment and review our sponsor categories for 2005, as well as our current andpast sponsors. In addition, we ask that you visit our sponsors’ Web sites by clicking on their logo or name.Thank you for your support.

Corporate Sponsorships

Diamond

($15,000 or more)

Platinum

($10,000 to $14,999)

Gold

($6,000 to $9,999)

Silver

($4,000 to $5,999)

Bronze

($2,000 to $3,999)

Patron

($1000 to $1,999)

Individuals & Sole Proprietorships

Diamond

($3,000 or more)

Platinum

($2,000 to $2,999)

Gold

($1,000 to $1,999)

Silver

($500 to $999)

Bronze

($300 to $499)

Patron

($100 to $299)

Sponsor Acknowledgment

All sponsors will be prominently acknowledged on a special page inserted in the 2005 and 2006 ConferenceAbstracts volume and CDs, and with large placards strategically placed throughout the meeting areas duringthese conferences.

Corporate-level Diamond sponsors will be acknowledged by having their logo displayed on the back jewelbox cover of the Conference CD. Corporate level Platinum sponsors will be acknowledged by having theirlogo placed on the first page of the CD. All contributions used for scholarships and/or grants will be givenwith acknowledgment of source.

In addition to the recognition provided to our sponsors in GCSSEPM publications, we proudly provide alink to our sponsors’ Web site. Just click on their logo or name to visit respective GCSSEPM sponsors.

The GCSSEPM Foundation is a 501(c)(3) exempt organization. Contributions to it are tax deductible ascharitable gifts and contributions.

For additional information about making a donation as a sponsor or patron, please contact Dr. Norman C.Rosen, Executive Director, GCSSEPM Foundation, 2719 S. Southern Oaks Drive, Houston, TX 77068-2610.Telephone (voice or fax) 281-586-0833 or e-mail at [email protected].

mailto:[email protected]

25th Annual Gulf Coast Section SEPM Foundation Bob F. Perkins Research Conference—2005 vii

2005 Sponsors

Corporate SponsorshipsPlatinum

Silver

Patron

Individuals & Sole ProprietorshipsSilver

Michael J. Nault Paul J. Post

Ed Picou

http://www.conocophillips.com

http://www.statoil.com

http://www.shell.com

http://www.bhpbilliton.com

http://www.kerr-mcgee.com

viii Program and Abstracts

2004 Sponsors

Corporate SponsorshipsSilver

Individuals & Sole ProprietorshipsSilver

Michael J. NaultEd Picou

BronzeAlan Lowrie

http://www.conocophillips.com

http://www.eogresources.com

http://www.hess.com

http://www.bhpbilliton.com

http://www.slb.com

http://www.slb.com

http://www.roxar.com

http://www.roxar.com

http://www.shell.com

25th Annual Gulf Coast Section SEPM Foundation Bob F. Perkins Research Conference—2005 ix

Credits

Graphics Design and CD ROM Publishing by

Rockport, Texaswww.bergan.com

Cover ImageThe cover image that was chosen for this year’s conference is a satellite image of Hurricane Katrina, one

of the stronger storm systems of modern times, reaching rare Category 5 status according to NOAA. Thisimage is credited to the GOES (Geostationary) 12 Satellite, NASA (National Aeronautics and SpaceAdministration)-GSFC (Goddard Space Flight Center), and data from NOAA (National Oceanic &Atmospheric Administration).

http://bergan.com

http://bergan.com

x Program and Abstracts

Petroleum Systems of Divergent Continental Margin Basins

25th Annual Gulf Coast Section SEPM FoundationBob F. Perkins Research Conference

Houston Marriott WestchaseHouston, Texas

December 4–7, 2005

Program

Sunday, December 4, 2005

4:00–6:00 p.m. Registration (Grand Foyer) and Poster Setup (Grand Pavilion)

6:00–8:00 p.m. Welcoming Reception and Poster Preview (Grand Pavilion)

Monday, December 5, 2005

7:00 a.m. Continuous Registration (Grand Foyer)

8:00 a.m. Welcome: Mike Styzen, Chair of the Board of Trustees, GCSSEPM Foundation (Grand Pavilion)

8:10 a.m. Introduction: Paul J. Post, Program Chair (Grand Pavilion)

Session I—Crustal Architecture of Divergent Margins

Co-Chairs: A.G. Doré and G. Karner

Keynote Address:

8:25 a.m. Doré, A.G. and Lundin, E.R.Challenges and Controversies in Exploration of the Northeast Atlantic Margin............. 1

8:50 a.m. Huismans, Ritske S. and Beaumont, ChristopherEffect of Lithospheric Stratification on Extensional Styles and Rift Basin Geometry ...... 5

9:15 a.m. Louden, Keith; Lau, Helen; Funck, Thomas; and Wu, Jack Large-Scale Structural Variations Across the Eastern Canadian Continental Margins: Documenting the Rift-to-Drift Transition ......................................................... 6

9:40 a.m. Refreshment Break and Posters

25th Annual Gulf Coast Section SEPM Foundation Bob F. Perkins Research Conference—2005 xi

Session I—Crustal Architecture of Divergent Margins (continued)

Co-Chairs: D. Brown and M.O. Withjack

10:05 a.m. Enachescu, Michael; Kearsey, Stephen; Hardy, Victoria; Sibuet, Jean-Claude; Hogg, John; Srivastava, Shiri; Fagan, Alphonsus; Thompson, Tim; and Ferguson, Renee

Evolution and Petroleum Potential of Orphan Basin, Offshore Newfoundland, and its Relation to the Movement and Rotation of Flemish Cap Based on Plate Kinematics of the North Atlantic .............................................................................................................. 7

10:30 a.m. Tari, Gabor and Molnar, JimCorrelation of Syn-Rift Structures Between Morocco and Nova Scotia, Canada ............ 9

10:55 a.m. Nemcok, Michal; Stuart, Charles; Segall, Marylin P.; Allen, Richardson B.; Christensen, Chelsea; Hermeston, Steven A.*; and Davison, Ian

Structural Development of Southern Morocco: Interaction of Tectonics and Deposition ....................................................................................................................... 10

11:20 a.m. Withjack, Martha Oliver and Schlische, Roy W.A Review of Tectonic Events on the Passive Margin of Eastern North America............ 11

11:45 a.m. Vågnes, Erling; Boavida, Joaquim; Jeronimo, Paulino; de Brito, Mateus; and Peliganga, Jose Manuel

Crustal Architecture of West African Rift Basins in the Deep-Water Province.............. 12

12:10–1:15 p.m. Lunch and Open Poster Booths

1:15 p.m. GCSSEPM Awards—Presenter: Mike Nault


Co-Chairs: W. Bosworth and W.G. Dickson

1:30 p.m. Rosendahl, B.R.; Mohriak, W.U.; Odegard, M.E.; Turner, J.P.; and Dickson, W.G.West African and Brazilian Conjugate Margins: Crustal Types, Architecture, and Plate Configurations (Part 1) ......................................................................................... 13

1:55 p.m. Rosendahl, B.R.; Mohriak, W.U.; Odegard, M.E.; Turner, J.P.; and Dickson, W.G.West African and Brazilian Conjugate Margins: Crustal Types, Architecture, and Plate Configurations (Part 2) ......................................................................................... 13

2:20 p.m. Ledesma-Vázquez, Jorge and Johnson, Markes E.Rift-to-Drift in the Baja California Central Domain of the Gulf of California, México 15

2:45 p.m. Bosworth, William and Burke, KevinEvolution of the Red Sea—Gulf of Aden Rift System ...................................................... 16

3:10 p.m. Refreshment Break and Posters


Co-Chairs: W.U. Mohriak and M.C. Guerra

3:35 p.m. St. John, BillTectonics of the Western Indian Ocean........................................................................... 17

xii Program and Abstracts

Session II—Salt- and Shale-Related Deformation on Divergent Margins

Keynote Address:

4:00 p.m. Mohriak, Webster UeipassSalt Tectonics in Atlantic-Type Sedimentary Basins: Brazilian and West African Perspectives Applied to the North Atlantic Margin ........................................................ 18

4:25 p.m. Ruffo, Paolo; Campobasso, Silvia; Fragola, Daniele; Massimi, Paolo; Scrofani, Giovanni; and Spadini, Giacomo

2D Computational Salt Tectonics: Passive Margins ...................................................... 19

4:50 p.m. Guerra, Marta Cardoso de Melo; Szatmari, Peter; and Pequena, MonicaAnalog Modeling of Salt-Related Structures in the South Atlantic................................. 20

5:30–8:00 p.m. Hot Buffet and Poster Session (Sessions will end at 5:15) (The cost of this buffet has been subsidized by a very generous grant from Statoil.)

Tuesday, December 6, 2005

Session II—Salt- and Shale-Related Deformation on Divergent Margins (continued)

Co-Chairs: I. Davison and J.C. Fiduk

8:00 a.m. Davison, IanTectonics of the South Atlantic Brazilian Salt Basins..................................................... 21

8:25 a.m Matias, Hugo; Mohriak, Webster; Menezes, Paulo; Sandnes, Frode; Barbosa, Valéria C. F.; Matias, Luis; and Santos, Fernando

Salt Distribution and Morphology in the Offshore Algarve Basin ................................. 22

8:50 a.m. Fainstein, Roberto and Krueger, AnaSalt Tectonics Comparisons Near Three Continent-Ocean Boundary Escarpments ..... 23

9:15 a.m. Dyson, Ian A.Evolution of Allochthonous Salt Systems During Development of a Divergent Margin: The Adelaide Geosyncline of South Australia................................................................. 24

9:40 a.m. Refreshment Break and Posters

Session II—Salt- and Shale-Related Deformation on Divergent Margins (continued)

Co-Chairs: S.L. Palmes and M.G. Rowan

10:05 a.m. Turner, Joshua CreviereTurtle Structures Created by Extension in a Low-Salt or Non-Salt Setting.................... 25

Session III—Sedimentation on Divergent Margins

10:30 a.m. Palmes, Stephen L.Relay Ramps and Lateral Ramps—Active Sediment Fairways During the Passive Margin Stage of Development of the Gulf of Mexico Basin ........................................... 26

25th Annual Gulf Coast Section SEPM Foundation Bob F. Perkins Research Conference—2005 xiii

10:55 a.m. Cibaj, Irfan and Zaugg, Patrick (presented by P. Imbert)Does the Frio Really Prograde in South Texas?............................................................. 27

11:20 a.m. Galloway, William E.Cenozoic Evolution of the Northern Gulf of Mexico Continental Margin...................... 28

11:45 a.m. Davis, Matthew H. and Goldhammer, R.K.The Tectonics of Tranquitas: A Field Study of Rift through Passive Margin Development and Laramide Deformation in Triassic and Jurassic Strata of the Sierra Madre Oriental, NE Mexico................................................................................. 29

12:10–1:30 p.m. Lunch and Open Poster Booths

Session III—Sedimentation on Divergent Margins (continued)

Co-Chairs: A. Danforth and X. Fort

1:30 p.m. Dyson, Ian A.Formation of Submarine Unconformities in Halotectonic Mini-Basins During Passive Margin Development of the Adelaide Geosyncline, South Australia.............................. 30

Session IV—Petroleum Systems of Divergent Margins

Keynote Address:

1:55 p.m. Rasmussen, Bjørn A.; Dreyer, Tom; and Martinsen, Ole J.Exploration in Rifted Atlantic Margin Basins: New Challenges and New Ideas—Or Just Business as Usual?............................................................................................. 31

2:20 p.m. Henry, Steven G.; Danforth, Al; and Venkatraman, SujataNew Insights from CongoSpan Pre-Stack Depth Migrated Imaging in Angola-Congo-Gabon: Petroleum Systems and Plays ............................................................................ 32

2:45 p.m. Fort, Xavier and Brun, Jean-PierreDeformation Induced Pathways for Hydrocarbon Migration Through the Aptian Salt Level in the Angolan Margin........................................................................................... 33

3:10 p.m. Refreshment Break and Posters

Session IV—Petroleum Systems of Divergent Margins (continued)

Co-Chairs: R.P. Bedregal and Don Olson

3:35 p.m. Love, F. R. and Stewart, D. J.Exploration Using a Linked System Approach to the Rift and Drift Sections in Brazil (abstract only) ................................................................................................................. 34

4:00 p.m. Bedregal, Ricardo Perez; Karner, Garry David; Gonçalves, Félix Thadeu Teixeira; Brito, Ademilson Fagundes; Küchle, Juliano; Filho, Elio Perez Cuiñas; Carneiro, Jason Thomas Guerreiro; and Fernandes, Flávio Luís

Petroleum Prospectivity of the Camamu-Almada Margin, Brazil: Insights from an Integrated Basin Analysis and Modeling Study .............................................................. 35

4:25 p.m. Dickson, William; Schiefelbein, Craig; Zumberge, John; and Odegard, MarkBasin Analysis in Brazilian and West African Conjugates: Combining Disciplines to Deconstruct Petroleum Systems ...................................................................................... 36

xiv Program and Abstracts

4:50 p.m. Darros de Matos, Renato M.Petroleum Systems Related to the Equatorial Transform Margin: Brazilian and West African Conjugate Basins ............................................................................................... 37

5:30–8:00 p.m. Beer, Wine, Snacks and Poster Session (Sessions will end at 5:15)

8:00 p.m. Authors Remove Posters(Contractor will remove display boards at 8:15 p.m.)

Wednesday, December 7, 2005


Co-Chairs: M. Bradshaw and D. Ryan

8:00 a.m. Sassen, Roger; Post, Paul J.; Jung, Woodong; DeFreitas, Debra A.; and McDade, Elizabeth C.

Laminated Lime Mudstone of the Early Oxfordian Smackover Formation of the Northern Gulf of Mexico Rim: Significance to Environments of Deposition of Carbonate Source Rocks in Rifted Basins....................................................................... 39

8:25 a.m. Williams, Kenneth E. and Madatov, Arkady G.Analysis of Pore Pressure Compartments in Extensional Basins................................... 40

8:50 a.m. Bradshaw, MaritaDivergent Continental Margin Basins—The Habitat of Australian Petroleum Systems 41

9:15 a.m. Ryan, Damien; Boreham, Chris; Krassay, Andrew; Deighton, Ian; and Cathro, DonnaSystems of the Otway Basin, Southern Australia: Oil and Gas in a Complex Multi-Phase Rift Basin .............................................................................................................. 43

9:40 a.m. Refreshment Break


Co-Chairs: G. Tari and G. Eisenstadt

10:05 a.m. Tari, GaborThe Divergent Continental Margins of the Jurassic Proto-Pannonian Basin: Implications for the Petroleum Systems of the Vienna Basin and the Moesian Platform .......................................................................................................................... 44

10:30 a.m. Dawson, William C.; Almon, William R.; Sangree, John B.; and the CALTEX Sequence Stratigraphy Team

Petroleum System and Miocene Sequence Stratigraphy: Central Sumatra Basin, Indonesia ........................................................................................................................ 45

Session V—Crustal Architecture of the Gulf of Mexico

10:55 a.m. Post, Paul J.Constraints on the Interpretation of the Origin and Early Development of the Gulf of Mexico Basin............................................................................................................... 46

25th Annual Gulf Coast Section SEPM Foundation Bob F. Perkins Research Conference—2005 xv

11:20 a.m. Odegard, Mark E.

Passive Margin Development in the Atlantic and Gulf of Mexico with a Special Emphasis on Proto-Oceanic Crust.................................................................................. 47

11:45 a.m. Johnson, Elizabeth A.E.; Kacewicz, Marek; Blickwede, Jon F.; and Huston, Holly H.

An Interpretation of the Crustal Framework and Continent-Oceanic Boundary in U.S. OCS of the Gulf of Mexico, Based on Gravity and Refraction Data Analysis ................ 48

12:10–1:30 p.m. Lunch

Session V—Crustal Architecture of the Gulf of Mexico (continued)

Co-Chairs: P.J. Post and M. Roberts

1:30 p.m. Calvert, Stephen and Cowgill, Mark

Oceanic Crust in the Gulf of Mexico—A Combination of Rift Propagation and Slow Spreading ........................................................................................................................ 49

1:55 p.m. Imbert, Patrice

The Mesozoic Opening of the Gulf of Mexico: Part 1, Evidence for Oceanic Accretion During and After Salt Deposition.................................................................................... 50

2:20 p.m. Imbert, Patrice and Philippe, Yann

The Mesozoic Opening of the Gulf of Mexico: Part 2, Integrating Seismic and Magnetic Data into a General Opening Model .............................................................. 51

2:45 p.m. Roberts, Michael; Hollister, Chris; Yarger, Harold; and Welch, Rhonda

Regional Geologic and Geophysical Observations Basinward of the Sigsbee Escarpment and Mississippi Fan Fold Belt, Central Deep-Water Gulf of Mexico: Hydrocarbon Prospectivity and Play Types.................................................................... 52

3:10 p.m. Conference Ends

Posters Only

Fiduk, Joseph C.; Gibbs, Peter B.; Brush, Eugene R.; Anderson, Lynn E.; Schultz, Thomas R.; and Schulz, Steven E.

Progradation and Retrogradation of the Libyan Shelf and Slope, North African Continental Margin ......................................................................................................... 53

Simms, Alex

The Importance of Glacio-Hydro-Isostasy Within the Late Quaternary/Holocene Sea-Level History of the Gulf of Mexico: Lessons for Stratigraphic Correlation .......... 54

Author Index ...............................................................................................................................A-1

xvi Program and Abstracts

125th Annual Gulf Coast Section SEPM Foundation Bob F. Perkins Research Conference—2005

Challenges and Controversies in Exploration of the Northeast Atlantic Margin

Doré, A.G.Statoil (UK) Ltd.11a Regent StreetLondon SW1Y 4ST, UK e-mail: [email protected]

Lundin, E.R.

Geological Survey of Norway

Leiv Erikssons vei 39

7491 Trondheim, Norway

Abstract

Despite some setbacks in the exploration of thisinitially highly prospective frontier province, oil andgas discoveries off mid-Norway, and, recently, on theFaroes and western United Kingdom shelf providecontinuing encouragement to exploration. Large partsof the area (including the northeast Greenland shelf, aportion of shelf similar in size to the productive areaoffshore mid-Norway) remain almost totally unex-plored. Therefore, numerous basic questions remainunanswered on the region’s geological evolution andpetroleum prospectivity. These include provenance andsource to sink relationships for the principal reservoirtargets (Cretaceous and Paleocene sandstones), and thedistribution and relative contribution to the hydrocar-bon budget of different source rocks. However, in thispaper, we concentrate on the fundamental problemsrelating to the lithosphere-mantle structure of the mar-gin. Many of these challenges stem from the status ofthe region as a classic volcanic passive margin.

The Northeast Atlantic (Fig. 1) is commonlyconsidered to be an archetype for volcanic passive mar-gins and the region is classified as a large igneousprovince (e.g. Coffin and Eldholm, 1992), referred toas the North Atlantic Igneous Province (NAIP). Flowbasalts (Fig. 2), the main phase of which just postdatedthe main (Paleocene) reservoirs of the region and justpredated northeast Atlantic breakup, create significantproblems in seismic imaging of reservoirs and traps.Conversely, attempts to resolve this problem haveresulted in significant strides in sub-basalt imaging,while locally intense seismic coverage has enhancedour knowledge of the 3D geometry of sills, dykes,vents, hyaloclastites, and other volcanic phenomena.

In general, the magmatic nature of the NAIP hasbeen attributed to Paleocene–early Eocene rifting andbreakup influenced by a mantle plume (White, 1988).However, it is difficult to explain all of the phenomenaassociated with the volcanic margin using this hypothe-sis, and there is significant controversy over the timing,

size, shape, and even existence of the early Tertiaryplume. The Iceland “hotspot”, although certainly rep-resenting an upper mantle upwelling at the currentspreading ridge, has few of the characteristics of a clas-sic deeply rooted plume, with most interpretationsshowing the low-velocity zone under Iceland beingconfined to the upper mantle (Foulger and Pearson,2001). It is by no means clear (and certainly cannot betaken for granted) that there is a direct link between thepresumed plume under Iceland and the formation ofthe early Cenozoic NAIP. The assumed link stems fromthe classic hotspot model of lithospheric drift (in thiscase, northwestwards) over a fixed plume emanatingfrom a very deep interface such as the core-mantleboundary. However, the “hotspot trail”, from WestGreenland, across Greenland to the present position ofIceland on the Atlantic spreading ridge (Lawver andMüller, 1994) that many regional interpretations treatas an a priori fact (Figs. 1 and 2) is neither proven noreven supported by the evidence. On the contrary, theapparent symmetry of the Greenland-Faroes Ridge(generally taken to represent the oceanic “hotspottrack”) in the ocean basins either side of Iceland sug-gests that the Iceland anomaly has remained fixed onthe constructional plate boundary (Lundin and Doré,2005, and in press). The near-simultaneous onset ofvolcanism in the NAIP at c. 62 Ma, in a line from Baf-fin Island to southwest Britain (thus crosscutting theline of eventual plate breakup), at a time when theplume should have impinged on the most northwest-erly outpost of the province, also creates difficulties forstandard plume models. For more on the Iceland issueand on the general debate on mantle plume models, seewww.mantleplumes.org.

Given the debate on the mantle and lithosphericcontrols, there is uncertainty surrounding the changesin basal heat flow associated with breakup that shouldbe assumed in constraining source rock maturation,hydrocarbon generation, and migration. One factor of


2 Program and Abstracts

key importance in the assessment of temperatures isthat of the distribution and nature of the anomalous,high-velocity, lower crustal body (HVLCB). This bodyis associated with the NAIP, identified on refractionand wide-angle seismic data, and commonly inter-preted as magmatic underplating fromdecompressional melting of a plume-influenced mantleduring final rifting and breakup (Fig. 2). The HVLCBis estimated by some workers to constitute as much as60–80% of the total estimated Paleocene magmaticrock volume in the NAIP (White et al., 1987).

A long-standing belief about magmatic under-plating is that buoyantly rising asthenospheric meltspond beneath the crust because they reach a level ofneutral density, spreading laterally to preferentiallyinfill the pre-existing Moho "topography", and formingthick pillows beneath rifts where the Moho was ele-vated. However, new ocean-bottom seismometer (OBS)work (Mjelde et al., 2005) reveals that the HVLCB ishighly variable both in thickness and internal velocity.The HVLCB does not seem to have filled in a pre-exist-ing Moho relief and seems to terminate abruptly againstmargin-perpendicular lineaments. These features seemto extend onshore into lineaments associated with col-lapse of the Caledonian Orogen along majordetachments oriented at high-angle to the orogenicfront (Olesen et al., 2004). The detachments limit large,exhumed basement culminations and separate high-grade metamorphic assemblages (including eclogites)from low-grade assemblages. Mjelde et al. (2005) sug-gest that the offshore lineaments separate regionscontaining magmatic underplating from regions of nor-mal mantle and/or from eclogite bodies. Likewise, non-magmatic portions of the inner-Norwegian margin areunderlain by HVLCBs, which are not interpreted asmagmatic underplating, but as in situ eclogite bodies(Christiansson et al, 2000) (Fig. 2). The nature of theHVLCB is highly relevant to hydrocarbon exploration,primarily with respect to heat flow. Where the HVLCBrepresents remnants from the Caledonian root zone, theinferred degree of crustal thinning (and hence heatflow) would be lower. At the other extreme, an up to10-km thick layer of underplating would generate atransient but significant heat pulse (Fjeldskaar et al.,2003).

Even accepting that the HVLCB can primarilybe attributed to underplating, its regional extent andeffect can be strongly debated. It is often widelyassumed that underplating underlies large portions ofnorthwest Europe, thereby explaining widespread Pale-ocene uplift and allowing predictions to be made ofelevated Paleocene–early Eocene heat flow (Clift,

1999). However, the actual extent of the HVLCB, asproven by refraction, OBS, and wide-angle seismicdata is essentially limited to the immediate continentalmargins (Fig. 2). A key issue may well be the nature ofmaterial at the base of the highly thinned crust in theRockall Trough. This area, generally believed to haveundergone lithospheric stretching during the Creta-ceous, would have been an ideal accumulation area forPaleocene asthenospheric melts, and recent velocitydata suggest that a sub-crustal layer in this region ismore likely to correspond with serpentinized uppermantle than with underplating (Morewood et al.,2005). Detailed thermal histories for the northeastAtlantic margin, based on apatite fission track and vit-rinite relectance data, appear to show no evidence forregionally consistent, anomalously high, early Tertiarybasal heat flows (Green et al. 1999). This is in contrastto what would be expected from models involving abroad plumehead and widespread underplating.

A further complicating factor in modelling thethermal history of the margin is the apparent mismatchbetween the limited extension (as manifested in brittlefaulting) observed in the upper crust compared to theamount of apparent thermal contraction (e.g., asobserved in the subsidence of subaerially extrudedlavas) following breakup. This apparent exception tothe standard McKenzie model of uniform lithosphericthinning may be a paradigm for passive margins at timeof breakup. This has been explained by depth-depen-dent stretching (Kusznir et al., 2005), a processwhereby the lower crust and mantle lithosphereundergo more stretching than the upper crust. The via-bility of this model is clearly critical to basin modellingand thermal maturation, since it implies considerablygreater input of heat into the system than would nor-mally be inferred from the observed crustal extension.However, considerable problems remain to be resolvedbefore this concept becomes useful in modelling thenortheast Atlantic and other passive margins. First, thephenomenon is always inferred from subsidence mod-elling rather than being observed directly aslithospheric thinning. Its existence is based on theassumption that the McKenzie thermal relaxationmodel is correct. Thus, the apparent contradictionbetween observed extension and subsidence must beresolved at depth, where it cannot be observed.Another, more radical, possibility is that the calculationmethod itself is inapplicable in this setting. Second, therelationship with the assumed underplate at the conti-nental margin is unclear. In most circumstances,addition of underplate at the base of the crust shouldcause isostatic uplift. Thus, both the vertical motions


and temperature effects of the two proposed phenom-ena – underplating and depth-dependent stretching –are difficult to disentangle. Third, the mechanism fordepth-dependent stretching (and, in particular, “dis-posal” of excess lower crust and lithosphere mantle) isunclear. Kusznir et al. (2005) have recently suggestedthat depth-dependent stretching occurs at, or immedi-ately after, inception of sea-floor spreading rather thanduring pre-breakup rifting, and propose that thinningof the lithosphere can be predicted as a function ofdivergent mantle flow from the mid-ocean ridge. Thismodel still requires substantiation in terms of the fateof lower lithospheric material and remains to be testedin a variety of settings (e.g., volcanic versus non-volca-nic passive margins).

Major phases of uplift and exhumation of boththe adjacent landmasses and some of the borderingbasins took place during the Cenozoic. The series ofsketch maps from late Paleocene to late Pliocene shownin Fig. 3 (after Lundin et al., 2004) illustrate the princi-pal uplift events and the controversies associated withthem. Latest Cretaceous–Eocene uplift was critical tothe distribution of reservoir rocks in the province,including input of sands into the northern North Seaand Faroe-Shetland basin and from Greenland in thewest to underexplored basins in the Faroes, mid-Nor-way, and the United Kingdom (Fig. 3A). Emergence oflandmasses in a region previously dominated by Creta-ceous marine shelves has been widely attributed to the“arrival” of the Iceland plume, causing transient(dynamic) uplift and permanent uplift (due to under-plating), while sand pulses in the Paleocene have beenattributed to variations in plume flux (White and Lovell,1997). However, a number of factors call into questionthat this vertical movement can be attributed to theimpingement of a single plumehead. These include: thewide variation of the uplift in time and space; the simul-taneous juxtaposition of uplift and subsidence along theincipient margin; and the uplift of areas such as main-land Norway (including northern Norway, supposedlyoutside of the main radius of plume influence) wherethere is neither evidence of volcanic activity nor geo-physical evidence for widespread underplating. Verticalmotions taking place after breakup also varied in timeand space, albeit with some episodes of greater syn-chronicity, and are even less amenable to theapplication of single mechanisms. For example, in theperiod immediately following breakup (early–middleEocene) most areas along the newly developed marginunderwent subsidence (e.g., North Sea, Faroe-ShetlandBasin, mid-Norwegian margin) while highs such as theRockall High and Porcupine Bank underwent uplift, the

latter causing delta progradation into the PorcupineBasin.

An important question pertains to the origin oflarge, gentle, compressional structures distributedalong the young sedimentary basins of the margin.These features formed in several episodes within theCenozoic, with most activity in the early Oligocene–Miocene (Fig. 3A and B). Because they deform pro-spective successions of Late Cretaceous and Paleoceneage, they are critical to the hydrocarbon migration andtrapping history of the northeast Atlantic margin.While the current authors (Lundin and Doré, 2002)suspect that the compressive structures can be attrib-uted to plate forces associated with the adjacent sea-floor spreading (ridge push/mantle drag), othersattribute them to far-field (Alpine) compressive stress.There is also considerable debate as to the contributionof compaction (fold flank loading) to the developmentof the structures. An association may also existbetween the structuring and fault reactivation duringthe plate reorganization occurring at Chron 13 (earliestOligocene, 35 Ma), during which plate motion in thenortheast Atlantic rotated from a northwest-southeastto a more west-east vector. At this time, the Arctic-Atlantic connection evolved from a shear margin to amore directly linked spreading axis (Fig 3B) and theLabrador Sea-Baffin Bay and Aegir spreading ridgeswere abandoned (Fig. 3C). Continued compressivedeformation probably also led to the development of amarine conduit across the previous land barrier of theGreenland-Faroes Ridge in middle Miocene times.This marine mixing resulted in the development ofmarine erosion surfaces, the redistribution of materialas contourite deposits in the southern northeast Atlan-tic (Fig. 3C), and may have contributed to thedeterioration of northern hemisphere climate (Stoker etal., 2005).

A widespread phase of late Neogene denudationaffecting Svalbard, the Barents Sea, northern andsouthern Norway, Scotland, and East and West Green-land caused a major redistribution of mass along themargin (Fig. 3D). The episode appears to have beenintimately associated with Northern Hemisphere glaci-ations and cannot be entirely accounted for by erosion,redeposition, and isostatic readjustment. Numerouslines of evidence (e.g., onshore measurements, off-shore forced regressions) show that initial upliftpredated glaciation and may indeed have been an addi-tional trigger for climate change. The causes of thisepisode are particularly enigmatic. Amagmatic uppermantle circulation changes may explain both this and,conceivably, earlier Cenozoic motions (Rohrman and


van der Beek 1996; Stoker et al., 2005). Resolution ofthe viability of this model versus other available mech-anisms is one of the more fundamental questions on thelarge-scale geology of the area. The late Neogene epi-sode exhumed numerous previous depocentres and had

a radical effect on the emplaced hydrocarbon systems(Doré et al., 2002). The effects of this phenomenon arefrequently underestimated in resource and risk assess-ments on the northeast Atlantic margin.


Effect of Lithospheric Stratification on Extensional Styles and Rift Basin Geometry

Huismans, Ritske S.Geodynamics Group, Department of Oceanography, Dalhousie UniversityHalifax (Nova Scotia), B3H 4J1, Canada e-mail: [email protected]

Beaumont, Christopher

Geodynamics Group, Department of Oceanography

Dalhousie University

Halifax (Nova Scotia), B3H 4J1, Canada

AbstractPlane-strain, thermo-mechanical, finite element

model experiments of lithospheric extension are usedto investigate the effects of strain softening in the fric-tional-plastic regime and the strength of the lower crustand mantle lithosphere, respectively, on the style ofextension. Crust and mantle lithosphere strength arevaried independently. A simple scaling of wet quartzand dry-olivine rheologies is used to examine crust andmantle lithosphere strength variations. Cases are com-pared where the crust is strong (ηwet quartz x 100), weak(ηwet quartz), or very weak (ηwet quartz /10), and themantle lithosphere is either strong (ηdry olivine) or weak(ηdry olivine/10). Strain softening takes the form of areduction in the internal angle of friction with increas-ing strain. Predicted rift modes belong to threefundamental types: (1) narrow, asymmetric rifting inwhich the geometry of both the upper and lower lithos-phere is approximately asymmetric; (2) narrow,

asymmetric, upper lithosphere rifting concomitant withnarrow, symmetric, lower lithosphere extension; and(3) wide, symmetric, crustal rifting concomitant withnarrow, mantle lithosphere extension. The differentstyles depend on the relative control of the system bythe frictional-plastic and ductile layers, which promotenarrow, localized rifting in the plastic layers and widemodes of extension in the viscous layers, respectively.A weak, ductile crust-mantle coupling tends to sup-press narrow rifting in the crustal layer. This is becauseit reduces the coupling between the frictional-plasticupper crust and localized rifting in the frictional-plasticupper mantle lithosphere. The simple strength variationmay be taken to represent end-member thermal and/orcompositional conditions in natural systems and therelevance for rifting of old, strong, and cold cratoniclithosphere as compared to young, “standard”, andmoderately weak Phanerozoic lithosphere is discussed.



Large-Scale Structural Variations Across the Eastern Canadian Continental Margins: Documenting the Rift-to-Drift Transition

Louden, KeithLau, HelenDepartment of OceanographyDalhousie UniversityHalifax, Nova Scotia B3H 4J1Canadae-mail: [email protected]

Funck, ThomasDepartment of GeophysicsGeological Survey of Denmark and Greenland (GEUS)Oster Voldgade 10DK-1350 Copenhagen KDenmark

Wu, JackDepartment of Earth SciencesDalhousie UniversityHalifax, Nova Scotia B3H 4J1Canada

AbstractThe eastern Canadian margins from Nova Scotia

to Newfoundland and Labrador formed during severalperiods of non-volcanic continental rifting from ~180Ma in the south, to ~60 Ma in the north. This paperdocuments the large-scale styles of structural variationsacross the deep-water regions of the rift-to-drift transi-tion on these margins. We present a series of seismictransects combining deep MCS reflection and wide-angle refraction profiles producing depth sections hav-ing similar scales and resolution. The combinedprofiles exhibit smaller scale structures defined by thereflectivity and larger scale variations defined by therefraction velocity models. These transects show sys-tematic patterns in which changes in crustal velocitiescan be clearly correlated with changes in reflectivity.All transects include complex variations across broad

transitions where the complete sequence from riftedcontinental crust to oceanic crust occurs over distancesof 200–300-km. Within the transition zone, the pres-ence of highly stretched continental crust can exist upto 200-km seaward of the hinge zone. The boundarybetween continental and oceanic crust is sometimes,but not always, separated by flat basement ~80-kmwide probably consisting of highly serpentinized uppermantle. An underlying region 150–200 km-wide of lessserpentinized mantle exists where faults cut throughthe thin crust. Large variations between upper andlower crustal extension occur both between and alongtransects controlling the deposition of syn-rift sedi-ment; while the deposition of post-rift sedimentfollows predictions based on the shape of the totalcrustal extension.



Evolution and Petroleum Potential of Orphan Basin, Offshore Newfoundland, and its Relation to the Movement and

Rotation of Flemish Cap Based on Plate Kinematics of the North Atlantic

Enachescu, MichaelKearsey, StephenHardy, VictoriaMemorial University of NewfoundlandPan-Atlantic Petroleum Systems Consortium P.O. Box 4778 St John’s, NL, A1B 3X5, Canadae-mail: [email protected]

Sibuet, Jean-ClaudeIFREMER Centre de Brest B.P. 7029280 Plouzané CedexFrance

Hogg, JohnEnCana CorporationP.O. Box 2189

421- 7th Ave SW Calgary, AB, T2P 4K9, Canada

Srivastava, ShiriGeological Survey of Canada Atlantic Bedford Institute of Oceanography PO Box 1006Darmouth, NS, B2Y 4A2, Canada

Fagan, AlphonsusGovernment of Newfoundland and LabradorDepartment of Natural ResourcesNatural Resources Bdg.,St John’s, NL, A1B 4J6, Canada

Thompson, TimFerguson, ReneeMemorial University of NewfoundlandPan-Atlantic Petroleum Systems Consortium P.O. Box 4778 St John’s, NL, A1B 3X5, Canada

Abstract

The Orphan Basin formed during the Mesozoicintra-continental extension, continental breakup, andNorth Atlantic Ocean opening. New seismic data col-lected in the Orphan Basin, and regional potential fielddata, show a wide non-volcanic rift area with two suc-cessive rift zones characterized by greatly stretchedcontinental crust. From both tectono-structural andpetroleum potential points of views, the Orphan riftedarea can be subdivided into an older East Orphan Basinsituated in deep water (1,500-3,000m) and a youngerWest Orphan Basin situated in shallower water (1000-1,500m). Seismic stratigraphic relationships indicatethat the first episode of rifting could be as old as theLate Triassic-Early Jurassic in the East Orphan Basin.A petroleum system including Kimmeridgian, marinesource rocks is postulated for this basin. A second rift-ing stage, from latest Late Jurassic to Early Cretaceous,created the eastern part of the West Orphan Basin andre-mobilized basement blocks and older sedimentaryfeatures in the east Orphan Basin. A third extensionalstage during mid-Cretaceous, probably coupled withLabrador Sea extension and opening, mostly affectedthe westernmost parts of the West Orphan Basin. Alater extensional stage is postulated to have occurred in

the early Tertiary, related to the initiation of a new riftbetween Greenland and northern Canada. The WestOrphan Basin petroleum system should be anchored byCretaceous or early Tertiary source rocks.

The two main rift basins, east and West Orphan,are separated by a major crustal fault zone, the WhiteSail fault dipping eastward and affecting the entireupper crust. The N 020° linear, tilted faults blocksidentified in the West Orphan Basin are perpendicularto the flow-lines of the herein proposed Flemish Capmotion during the M25-M0 period, giving an indepen-dent evidence of the validity of the Flemish Cap/NorthAmerica reconstruction at chron M25 derived frommagnetic and gravity data. On the M0 reconstruction,the east and West Orphan basins are located in front ofthe Porcupine basin and Rockall trough respectively.

The Flemish Cap behaved as a large, monolithiccontinental block and rotated clockwise 43º, apparentlymoving more than 200 km to the southeast, while theupper crust of the east Orphan Basin has a = 2.5 aver-age stretching from Late Triassic to early Tertiary.Regional seismic data suggest that trans-tensionalmovements, although hard to identify on reflectiondata, played an important role and continued until the


http://www-odp.tamu.edu/publications/210_IR/210ir.htm


Paleocene. Beyond the Orphan Knoll-Flemish Cap“outer ridge” lineament lies a true divergent marginbasin showing little deformation within the sedimen-

tary sequence and which overlies a relatively widecontinent-ocean transition zone.


Correlation of Syn-Rift Structures Between Morocco and Nova Scotia, Canada

Tari, GaborMolnar, JimVanco Energy Company

Three Greenway Plaza, 12th FloorHouston, Texas 77046e-mail: [email protected]

AbstractReconstructions of the relative positions of the

North American and African continents before theopening of the Central Atlantic Ocean have either beenbased on morphological fits using coastlines/isobathsor seafloor magnetic/fracture data. Additional con-straints for the best fit between these continents maycome from pre-rift structural elements if they are suffi-ciently oblique to the line of rifting. None of theexisting reconstructions utilize syn-rift structures,which are expected to be preserved on the conjugatepassive margins. We report a direct correlation of syn-

rift structures across the Central Atlantic based on newreflection seismic and potential field data.

The prominent basement high of the TafelneyPlateau, offshore Morocco, is interpreted as a high-relief accommodation zone analogous to many wellstudied examples in the present-day East African riftsystem. It developed between two regional-scale, nor-mal fault systems with opposing polarities. The actualEarly to Middle Jurassic breakup occurred obliquelyacross the Tafelney accommodation zone leaving mostof it on the Moroccan margin.



Structural Development of Southern Morocco: Interaction of Tectonics and Deposition

Nemcok, Michal

Stuart, Charles

Segall, Marylin P.

Allen, Richardson B.

Christensen, Chelsea

Energy and Geoscience Institute at University of Utah

423 Wakara Way, Suite 300

Salt Lake City, Utah 84108, USA

e-mail: [email protected]

Hermeston, Steven A.*Kerr-McGee Oil and Gas Corporation 16666 NorthchaseHouston, Texas 77060, USA *present address: Occidental Oil and Gas Corporation 5 Greenway Plaza, Suite 110Houston, Texas 77046-0506

Davison, IanEarthmoves Ltd. Chartley House38-42 Upper Park Road Camberley, Surrey GU15 2EF, UK

AbstractInterpretation of magnetic, gravity, seismic, and

geological data shows that the curvilinear Late Paleo-zoic orogen affected the location of Central Atlanticsyn-rift faults. While northeast-southwest strikingthrust faults were perpendicular to extension, promi-nent curvatures, such as the Pennsylvania salient,introduced structural complexities. East-northeast/west-southwest striking, dextral, transpressional strike-slip faults of this salient became reactivated duringCarnian-Toarcian rifting. They formed sinistral, tran-stensional strike-slip “rails” that prevented the GeorgesBank–Tarfaya Central Atlantic segment from orthogo-nal rifting, causing formation of a pull-apart basinsystem. Central Atlantic segments to the south andnorth underwent almost orthogonal rifting. “Rails” losttheir function after the continental breakup, except forminor younger reactivations. They were not kinemati-cally linked to younger oceanic fracture zones.

Atlantic segments initiated by normal rifting dif-fer from the segment initiated by the Georges Bank–

Tarfaya strike-slip fault zone. They contain Upper Tri-assic-Lower Jurassic evaporites having salt-detachedgravity glides, while the connecting transfer segmentdoes not. Their structural grain is relatively simple,divided mostly by northeast-southwest striking normalfaults. Northwest-southeast striking oceanic fracturezones kinematically link with continental faults in afew places, controlling the sediment transport path-ways across the uplifted continental margin.

The connecting Georges Bank–Tarfaya CentralAtlantic segment, initiated as a sinistral transfer-zone,has a complex structural grain, characterized bynumerous small depocenters and culminations. Theirboundaries are formed by east-northeast/west-south-west striking, sinistral, strike-slip, north-northeast/south-southwest, striking normal and west-northwest/east-southeast striking, dextral, strike-slip faults. Sedi-ment transport pathways have complex trajectories,weaving through local depocenters.



A Review of Tectonic Events on the Passive Margin of Eastern North America

Withjack, Martha OliverSchlische, Roy W.Department of Geological SciencesRutgers UniversityPiscataway, New Jersey 08854-8066e-mail: [email protected]

AbstractField, seismic, and drill-hole data provide a

wealth of information about the tectonic processesassociated with rifting, breakup, and the early stages ofseafloor spreading for the passive margin of easternNorth America. The onset of rifting, from Florida tothe Canadian Grand Banks, was approximately syn-chronous, occurring by Late Triassic time. Thecessation of rifting (and presumably the onset of drift-ing) was diachronous, occurring first in thesoutheastern United States (latest Triassic), then in thenortheastern United States and southeastern Canada(Early Jurassic), and finally in the Grand Banks (EarlyCretaceous). The Central Atlantic Magmatic Provincedeveloped simultaneously (earliest Jurassic, ~200 Ma)throughout eastern North America. This magmaticactivity occurred after rifting in the southeasternUnited States, and during rifting in the northeasternUnited States and maritime Canada. The passive mar-

gin, from Florida to southern Nova Scotia, is volcanic,characterized by seaward-dipping reflectors (SDRs)near the continent-ocean boundary. The remainder ofthe passive margin lacks SDRs and is, thus, non-volca-nic. In the continental crust, most rift-related structuresparallel pre-existing zones of weakness created byPaleozoic and older orogenies. Few transfer zonesexist, and these also parallel the pre-existing fabric. Inthe oceanic crust, fracture zones parallel the directionof relative plate motion. Thus, the trends of the fracturezones in the oceanic crust differ from the trends of therift-related structures in the continental crust. Thedeformational regime changed substantially after rift-ing throughout eastern North America: post-riftshortening (inversion) replaced syn-rift extension.Detached structures associated with salt movementalso developed after rifting, especially on the Scotianshelf and Grand Banks.



Crustal Architecture of West African Rift Basins in the Deep-Water Province

Vågnes, ErlingHydro Oil & Energy, N-5254 Sandsli, Norwaye-mail: [email protected]

Boavida, JoaquimUniversity Agostinho Neto Avenida 4 Fevereiro 79Luanda, Angolae-mail: [email protected]

Jeronimo, PaulinoSONANGOL PESQUISA E PRODUCAO SARL. Rua Comandante Dack Doy No 2, Bairro AzulLuanda, Angola

de Brito, MateusSONANGOL-DEX, Av. 4 de Fevereiro 214Luanda, Angola

Peliganga, Jose ManuelUniversity Agostinho Neto Avenida 4 Fevereiro 79Luanda, AngolaAlso at: Total Angola

AbstractWe used a reprocessed 2D seismic line across the

ultra-deep water area offshore Angola to map a thickpre-salt sequence divided by a prominent angularunconformity into two main packages. The seismic lineshows a strong reflector at ca 9 seconds two-way time(twt), possibly the crust-mantle boundary (Moho).

We interpret that the pre-salt strata records majorcrustal extension, followed by rapid sedimentation.Pre-salt decompacted sedimentation rates were inexcess of 200–600 m/My, in contrast to a maximumpost-salt deposition rate of 50 m/My. This suggests thatthe transition from pre-salt to post-salt deposition coin-cided with a dramatic change in climate and/ordrainage pattern. This is also indicated by the change

from mainly lacustrine clastics in the pre-salt sequenceto mainly carbonates in the immediate post-saltsequence.

The total post-rift subsidence in the study areaindicates a crustal extension factor between 2.3 and3.4, increasing from east to west. An alternative esti-mate of crustal extension, ranging from 3.6 to 4.9, isobtained by assuming that the 9 seconds twt reflector isthe Moho. These differing estimates may be reconciledif it is assumed that the study area is uplifted by ca. 750m relative to the McKenzie (1978) subsidence modelpredictions. It is noteworthy that an uplift of this mag-nitude corresponds to the current uplift of continentalsouthern Africa.




West African and Brazilian Conjugate Margins: Crustal Types, Architecture, and Plate Configurations

Rosendahl, B.R.

Rosenstiel School of Marine and Atmospheric Science, University of Miami

4600 Rickenbacker Causeway

Miami, Florida 33149


Mohriak, W.U.

Petroleo Brasileiro S.A., E&P- CORP – UN-EXP and UERJ

Avenida Chile 65-s. 1302

20035 900 Rio de Janeiro, R.J., Brazil


Odegard, M.E.Chief GeophysicistGrizzly Geosciences, Inc.14019 SW Freeway, Suite 301-735Sugar Land, Texas 77478

Turner, J.P.University of BirminghamEarth SciencesSchool of Geography, Earth & Environmental SciencesBirmingham B15 2TT, UK

Dickson, W.G.Dickson International Geosciences12503 Exchange Drive, Suite 510AStafford, Texas 77477

AbstractA combination of seismic reflection and gravi-

metric imagery has been used to map four sectors ofproto-oceanic crust along conjugate segments of theWest African and Brazilian margins. These form corri-dors isolating oceanic crust, produced about the post-118 Ma pole of rotation, from continental crust. Sea-ward of the proto-oceanic crust/oceanic crustboundary, relatively uniform, thin oceanic crust (4.2–6.5 km thick) has been generated at the paleo-Mid-Atlantic Ridge. Structural variability is limited largelyto fracture zones. Proto-oceanic crust in the northernsectors (i.e., Kribi, Mbini, and Ogooue) is up to 10 kmthick, block-faulted, compartmentalized, and seismi-cally layered. These sectors of proto-oceanic crustlikely were generated by slow spreading, as the relativeplate motions evolved from left-lateral dislocationalong the Sergipe-Alagoas transform to full-fledgedspreading. Thus, proto-oceanic crust in the north is theproduct of a leaky transform fault and records the evo-lution from disorganized to organized spreading undera changing stress regime. Proto-oceanic crust in thesouthern sector, the Gabon sector, may consist of sliv-ers of lower crustal or upper mantle rocks emplacedalong detachments and unroofed as the Gabon upperplate detached from the Brazil lower plate. The ocean-continent boundary marks the transition from deeply-subsided proto-oceanic crust to relatively elevated con-tinental crust.

Merging the mapped oceanic crust/proto-oceaniccrust boundaries from the conjugate margins results in

a rigid closure model at about 118 Ma for this part ofthe Atlantic. Merging the mapped ocean-continentboundaries (i.e., removing proto-oceanic crust) pro-duces a Neocomian rigid closure fitting the continentalsectors of the African and South American plates. Priorto this stage, and beginning in earliest Neocomian,continental deformation was dominated by sinistralshear along the Sergipe-Alagoas transform, parallel to

the West African margin between 3° north–1° south (orparallel to the Brazilian margin between 8°–13° south).Shear along the transform produced a complex swathof transcurrent fault branches, relays, pull-apart basins,and transpressional ridges. Conjugate fits of pairedseismic lines from the two margins indicate the SouthAmerican plate moved more than 100 km southwestrelative to the African plate, prior to a 40° change inplate motion direction leading to genesis of proto-oce-anic crust. Dislocation along the transform obliquelyextended both the Gabon rift zone to the south of thetransform, and the Jatobá-Tucano-Recôncavo rift zonemarking the western boundary of the Sergipe micro-plate. Conjugate seismic pairings across the adjoinedBrazil and Gabon rift zone margins show that a simpleshear mode of extension developed in this area as dis-location along the transform progressed. The low-anglemain décollement dips toward the Gabonese side anddeepens beneath it, dividing a narrow band of abruptlyextended São Francisco cratonic crust (lower plate)from a broad zone of extended Congo fold belt rocks(upper plate). With the 40° change in plate motion




direction and the onset of seafloor spreading, extensionof the Gabon rift zone ceased and the Jatobá-Tucano-Recôncavo rift zone became an aulacogen.

The plate closure scenarios presented here havean important bearing on matching rock units and basinsfrom the two margins, particularly in an exploration

context. The scenarios also explain why previousattempts to pair apparent conjugate seismic lines fromoffshore Brazil and West Africa have been unable toconsistently match both continental and oceanic crustalsectors.


Rift-to-Drift in the Baja California Central Domain of the Gulf of California, México

Ledesma-Vázquez, JorgeÁrea de GeologíaFacultad de Ciencias Marinas, UABCEnsenada, Baja California 22800Méxicoe-mail: [email protected]

Johnson, Markes E.Geosciences Dept.

Williams College

Williamstown, Massachusetts 01267

USA

Abstract Extensional tectonics in the Gulf of California

region occurred during middle- to early-late Miocenetime. One of the best examples is found at Bahía Con-cepción, which is the largest fault-bound bay on thepeninsular gulf coast of Baja California. The exten-sional basin confined to Bahía Concepción developedwithin an accommodation zone related to the lateMiocene east-west extension in the broader Gulf ofCalifornia region. This contribution is focused on thelarge, central part of the gulf region along the peninsu-lar axis, sometimes referred to as the Baja CaliforniaCentral Domain (BCCD).

The mainly volcanic Comondú Group is exten-sively exposed throughout the BCCD, but on a localbasis it occurs as huge andesite blocks associated withstratified units that characteristically dip in oppositedirections. This is a direct result of a main east-westextensional episode that generated normal faults on thesurface and listric detachment faults at depth. Half gra-bens are the most common result of such extensional

episodes in the BCCD. This event has produced sub-sidence, creating depocenters for mostly nearshoremarine basins. The oldest marine sedimentary unitspresent in the BCCD are the late Miocene–earlyPliocene Tirabuzón Formation. Less typically, on Pen-insula Concepción and at Punta San Antonio, a lateMiocene extensional episode has resulted in up-throwngranodiorite basement along bounding faults. Exten-sion on the Bahía Concepción zone was responsible fordevelopment of a half-graben structure first fullyflooded in late Pliocene time.

The tectono-sedimentary evolution of the adja-cent Santa Rosalía and Bahía Concepción areas isrecorded by three stratigraphic stages: (1) pre-rift stratarepresented by the Comondú Group; (2) a syn-rift stagecontaining syntectonic siliciclastic deposits; and(3) post-rift strata, represented by the late Miocene toPliocene flat-lying to low-angle marine sedimentaryunits. The three stratigraphic stages are interpretedfrom outcrops in this region.



Evolution of the Red Sea—Gulf of Aden Rift System

Bosworth, WilliamMarathon Oil CompanyP.O. Box 3128Houston, Texas 77253e-mail: [email protected]

Burke, KevinUniversity of HoustonDepartment of GeosciencesUniversity of HoustonHouston, Texas 77024-5507

AbstractThe Red Sea—Gulf of Aden rift System pro-

vides a superb example of the formation of passivecontinental margins. Three phases are well repre-sented: (1) continental rifting (Gulf of Suez); (2) rift-to-drift transition (northern Red Sea); and (3) sea-floorspreading (Gulf of Aden and southern Red Sea).Recently published radiometric and biostratigraphicages, outcrop studies, and reflection seismic profilesmore tightly constrain the evolution of this rift system.The principal driving force for separation of Arabiafrom Africa was slab-pull beneath the approachingUrumieh-Dokhtar volcanic arc on the north side ofNeotethys. However, the rifting trigger was impinge-ment of the Afar plume beneath northeast Africa at ~31Ma. Rifting followed quickly thereafter, initiating inthe Gulf of Aden, perhaps in the area between SocotraIsland and southern Oman. Extension occurred in thecentral Gulf of Aden by ~29 Ma. Shortly thereafter, at~27 Ma, rifting jumped to Eritrea, east of the Danakilregion. Rifting then spread from Eritrea to Egypt at~24 Ma, accompanied by a major dike-emplacementevent that covered more than 2,000 km in possibly less

than 1 Ma. At ~14 Ma, the Levant transform boundaryformed, largely isolating the Gulf of Suez from laterextension. Constriction of the Suez-Mediterranean andRed Sea-Aden marine connections resulted in wide-spread evaporite deposition at this time. Sea-floorspreading began in the eastern Gulf of Aden at ~19 Ma,the western Gulf of Aden at ~10 Ma, and in the south-central Red Sea at ~5 Ma. Propagation of the oceanicridge has taken much longer than the propagation of itscontinental rift predecessor. Therefore, the rift-to-drifttransition is diachronous and is not marked by a spe-cific “breakup” unconformity. The Red Sea sub-basinsare each structurally asymmetric during the syn-riftphase and this is seen in the geometries obtained whenits present paired conjugate margins are palinspasti-cally restored. During the Late Miocene and Pliocene,regional-scale, intra-salt detachment faulting, salt flow-age, and mass-movement of the post-Miocene saltsection toward the basin axis masked the deeper faultblock geometry of most of the Red Sea basin. Thisyoung halokinesis has enormous consequences forhydrocarbon exploration.



Tectonics of the Western Indian Ocean

St. John, Bill2105 West Ridge CircleKerrville, Texas 78028e-mail: [email protected]

Abstract The tectonic province of the western Indian

Ocean is defined by the East Africa Rift Zone to thewest and by the Ninety-East Ridge to the east. The areais bounded to the north by the Arabian Peninsula and tothe south by the southern Indian Ocean spreading cen-ter. The topography-bathymetry is dominated by thetriple-junction Indian Ocean spreading center, the man-tle plume extrusions forming the Laccadives-Maldives-Chagos and Mascarene Plateau-Mauritius-Reunionchains of volcanic archipelagos and islands, and themantle plume extrusion of the Ninety-East Ridge.

Initial breakup of ancestral Gondwana, sea floorspreading, and appearance of oceanic crust was pre-ceded by continental sag and development of the LateCarboniferous–Early Jurassic Karoo basins. The firstoceanic crust appeared in the Middle Jurassic as theAfrica-Arabia plate moved northward relative to theIndia-Seychelles-Madagascar-Australia-Antarcticaplate. This north-south separation continued throughthe Neocomian.

A major jump in the spreading center occurred inearliest Barremian with Antarctica-Australia separat-ing from India-Seychelles-Madagascar. Madagascarseparated from India-Seychelles via a transform faultalong the east coast of Madagascar. The trans-tensionaltransform evolved into a spreading center during themiddle Cretaceous Barremian-Aptian-Albian as oce-anic crust appeared. The mantle plume Rajmahal Trapsfirst appeared in eastern India during the Aptian-

Albian, and as the Indian plate continued to migratenorthward, evolved into the Ninety-East Ridge.

The mantle plume-derived volcanic rocks of theDeccan Traps first appeared in western India near theCretaceous-Tertiary boundary. The Seychelles began toseparate from India in the early Paleocene. By the closeof the Paleocene, a broad expanse of oceanic crust sep-arated the Seychelles and western India. The mantleplume formed an extensive oceanic ridge that becamethe Laccadives-Maldives-Mascarene Plateau. Begin-ning in the Eocene and continuing through theOligocene, the ongoing spreading center split the oce-anic ridge. North of the spreading center, mantleactivity extended the Laccadives-Maldives to includethe Oligocene-age Chagos Archipelago, while south ofthe spreading center, the Mascarene Plateau basaltscontinued as the Saya de Malha and Nazareth Banks.Mantle plume extrusion continued to the south as theplate moved northward, creating Mauritius Island dur-ing the Miocene and Reunion Island during Pliocene-Recent.

To the northwest, Red Sea separation of Egyptfrom Arabia began during the Oligocene. Extension ofthe Indian Ocean spreading center into the Gulf ofAden between Somalia and Yemen-Oman did notoccur until the Miocene.

To the north in Ethiopia-Eritrea, the East AfricaRift Zone originated during the early Miocene and hasextended southward through Uganda-Kenya-Tanzania-Mozambique into the southern Indian Ocean.



Salt Tectonics in Atlantic-Type Sedimentary Basins: Brazilian and West African Perspectives Applied to the North Atlantic Margin

Mohriak, Webster UeipassSenior Geologist – Technical ConsultantPetrobras - E&P-CORP/UN-EXP/GP-SSE and UERJe-mail: [email protected]

Abstract The South American divergent continental mar-

gin extends from eastern Brazil towards the continentalmargin off Argentina. This segment is limited, both tothe north and south, by transcurrent movements associ-ated with oceanic fracture zones and by the subductionzone north of Antarctica. Within the extensional mar-gin, the transitional phase salt basins are alsocontrolled by transform faults in the eastern Brazilianand West African margins. The evaporite basin is asso-ciated with siliciclastic and carbonate sedimentsdeposited above a regional unconformity (breakupunconformity) that marks the beginning of the conti-nental drift phase. This was followed by Aptianevaporite sedimentation between the Sergipe-Alagoasand Santos basins on the Brazilian side, and from theRio Muni to Benguela basin in West Africa. Theevaporitic conditions seem to extend up to early Albianin some regions, as evidenced by extremely thick lay-ers of stratified evaporites, indicating several

depositional cycles. A highly mobile evaporite layerresulted in the development of a characteristic tectonicstyle marked by salt diapirs, and extensional and com-pressional structures affecting the post-saltsedimentary successions.

The regional deep-penetration seismic profilesacquired in the South Atlantic provide a unique datasetallowing identification of salt tectonic domains fromthe platform towards the oceanic crust boundary. Theseprolific hydrocarbon-bearing salt basins constitute aframework for the interpretation of the less-exploredsalt basins of the North Atlantic continental margins,particularly along the Iberian and North American con-tinental margins. Examples of analogue autochthonousand allochthonous salt structures, and their geody-namic evolution, have important implications forpetroleum exploration in the deep-water frontierregions.



2D Computational Salt Tectonics: Passive Margins

Ruffo, PaoloCampobasso, SilviaFragola, DanieleENI E&P DivisionVia Emilia N°1,20090 San Donato Milanese (MI)Italye-mail: [email protected]

Massimi, PaoloScrofani, GiovanniMOX – Dipartimento di Matematica “F. Brioschi”Politecnico di MilanoVia Bonardi N° 9,20133 Milano (MI)Italy

Spadini, GiacomoENI Petroleum1201 Louisiana #3500Houston, Texas 77002

Abstract Salt tectonics has attracted considerable attention

in the last few decades because of its importance incontrolling the location of hydrocarbon reserves. As aconsequence of its low density and viscous nature, saltis can be deformed by buoyant flow over geologicaltime, deforming and penetrating overlying sedimentarysequences. Salt can act directly as a hydrocarbon seal,and salt-related deformation may totally change thestratigraphic and structural interpretation through thegeohistory of the basin. Timing of the salt tectonic evo-lution may be crucial for hydrocarbon exploration, notonly because the structural traps indicated on present-day seismic data may not have been in-place whilehydrocarbons were migrating into the area, but also forthe direct effect that salt geometries have on tempera-ture distribution and therefore on hydrocarbongeneration and expulsion. The economic consequencesof increased understanding of salt movements are thussignificant.

A 2D finite element numerical code has beendeveloped to allow study of salt motion impact on thestructural evolution of a passive margin. In the numeri-cal code, salt and the other sediments are considered asa continuous media possessing variable propertiesin space and time. Salt is modeled with viscous Newto-nian rheology and the overburden with a pseudo-plasticnon-Newtonian rheology. The spatial mesh used in thenumerical model is triangular, unstructured, and non-uniform. The interfaces between layers are tracked(during evolution) using a lagrangian approach, and, inorder to improve the resolution of the tracked inter-faces, refinement and de-refinement techniques havebeen implemented.

A real case study was developed focusing atten-tion on the impact of: sediment density, rheologicalparameters, and progradation rate of the pre-/sin-kine-matic sequences on the evolution of passive margins.This offered a better understanding of salt behavior in acomplex structural context.



Analog Modeling of Salt-Related Structures in the South Atlantic

Guerra, Marta Cardoso de MeloSzatmari, PeterPequena, MonicaPetrobras Research CenterCidade Universitária - Quadra 7 - Ilha do Fundão - Rio de Janeiro - RJ - 21949-900 - Brazile-mail: [email protected]

AbstractAnalog modeling is an important tool to enhance

the understanding of the genesis and evolution of geo-logical processes, as well as of the geometry of theresultant structures, since it provides good three-dimensional views of the different stages of theirdevelopment, in a time scale compatible with humanobservation. The evolution of the South Atlantic saltbasins, especially those located at the southeasternBrazilian continental margin, has been the subject of aseries of analog models carried out in the GeotectonicsLaboratory of Petrobras.

A novel technique of analog modeling has beendeveloped by Petrobras to permit simultaneous studyof salt-related structures and turbidite distribution inevaporite basins. The natural conditions where the pro-cesses of turbidity currents develop are wellreproduced, showing realistic models of the shelf andslope systems of the South Atlantic basins.

Previous analog modeling studies of salt tectonicprocesses using silicone to simulate salt, and dry sandto simulate the overlying sediments has resulted inmajor advances in our understanding of salt tectonicprocesses. The control of salt tectonics by normal fault-ing of the overlying sediments has been clearlydemonstrated. Nevertheless, active salt diapirism andthe formation of salt canopies are not readily repro-

duced by such a modeling technique. A new approach,entirely developed at the Petrobras Geotectonics Labo-ratory, has been to submerge both the silicone and theoverlying sand in water. The saturated sand layer hasits shear strength reduced by increased pore pressurewhile total overburden pressure increases. As a result,buoyancy-related structures form promptly and thesand is more liable to produce compressive structures.The resulting structures closely resemble diapirs andcanopies well known from deep-water environments.Another great advantage is that subaqueous modelingpermits combining sedimentation, including genera-tion of turbidite channels and fans, with simultaneoussalt tectonics, revealing their intricate interactions andmutual controls. Exaggeration of the density contraststhus helps to reproduce otherwise hard to achievestructures that are abundantly seen in nature, eventhough the intentionally distorted dimensioning shouldbe treated with caution in the detailed physical inter-pretation of the results.

The models reproduce with great accuracy thesalt-related structures observed in South Atlantic conti-nental margin basins and may thus support seismicinterpretation and hydrocarbon exploration in thesebasins.



Tectonics of the South Atlantic Brazilian Salt Basins

Davison, IanEarthmoves Ltd.Chartley House38-42 Upper Park RoadCamberleySurrey, GU15 2EF, UK.e-mail: [email protected]

Abstract This paper compares and contrasts salt tectonics

on two different types of continental margins in Brazil. Narrow margins, such as the Jequitinhonha and

Camamu basins, are 50–100 km wide and have a steep,(up to 5°) seaward-dipping base of salt seismic hori-zon. These margins are sediment starved due to theirsteepness. Consequently, sediment has bypassed thesalt basin and been deposited on the abyssal plain. Pro-nounced contractional folding of the salt overburden ispresent on these margins. This commenced at theoceanward pinch-out of the salt and propagated backup the continental slope into areas, which are expectedto be in extension due to gravity sliding. This is theopposite sense of fold and thrust propagation comparedto ‘normal’ mountain fold and thrust belts. The bathy-metric highs above pre-existing diapirs and foldanticline crests were rapidly eroded on narrow mar-gins, which allowed the folds to grow more easily tolarge amplitudes (1.5 km) at the top salt seismic hori-zon. Folds continued to unroof until the salt reachedthe seabed and produced a duck-head shaped diapirdue to downslope flow of a salt glacier. This was fol-

lowed by collapse of the salt structure producing anunconformity-bounded graben.

Wide margins, such as the Campos and Santosbasins, are >100 km and <650 km wide and have a sub-horizontal to landward-dipping base of salt seismichorizon. Salt basins on wide margins are effective sedi-ment traps; e.g., sediment loading in the Santos basinhas produced a 2° landward-dipping base salt seismichorizon across the outer portion of the basin. Landwarddip at the base salt seismic horizon has promoteddevelopment of counter-regional faults and enhancedlater folding, which appear to develop approximatelysimultaneously across the whole basin. The folds arelimited in amplitude to a maximum of 1 km, as little orno erosion has taken place over the crests and the thicksediment lid above the salt structures produces morecompetent rocks, causing a high vertical confiningpressure, which inhibits fold growth. This compressionis probably due to both downslope gravity sliding, andregional tectonic compression is due to ridge push orAndean collisional events.



Salt Distribution and Morphology in the Offshore Algarve Basin

Matias, HugoCentro de Geofísica da Universidade de LisboaEdificio C8, Piso 6, Campo Grande, 1749-016 Lisboa, Portugale-mail: [email protected]

Mohriak, WebsterUERJ - Faculdade de Geologia / PetrobrasPavilhão João Lyra Filho, 4º andar, Rio de Janeiro, BrasilMenezes, PauloUERJ - Faculdade de GeologiaPavilhão João Lyra Filho, 4º andar, Rio de Janeiro, BrasilSandnes, FrodeTGSBaarsrudveien 2, N-3478 Naersnes, Norway

Barbosa, Valéria C. F.LNCC – Laboratório Nacional de Computação Cientí-ficaAv. Getúlio Vargas 333, Petrópolis – Rio de Janeiro 25651-075, BrazilMatias, LuisCentro de Geofísica da Universidade de LisboaEdificio C8, Piso 6, Campo Grande, 1749-016 Lisboa, PortugalSantos, FernandoCentro de Geofísica da Universidade de LisboaEdificio C8, Piso 6, Campo Grande, 1749-016 Lisboa, Portugal

AbstractThe Algarve basin developed as an extensional

basin during the Mesozoic, associated with northwest-southeast transtension in ending at the Azores-Gibral-tar plate boundary. Several main episodes could beidentified in the evolution of this plate boundary: Trias-sic rifting and mid-Atlantic extension until the EarlyCretaceous; fracturing and strike-slip movement alongthe Azores-Gibraltar Fracture Zone, from Early Juras-sic to lower Eocene; continental convergence betweenEurope and Africa, beginning in the Late Cretaceous,reaching its culmination during the Neogene.

The study of the Algarve basin began with theinterpretation of 2D MCS seismic profiles generatingstructural and isopach maps. These maps show thegeometry of the basin to be asymmetric, associatedwith a depocenter striking northeast-southwest andlocated very close to Guadalquivir ridge.

Two salt units are interpreted in the Algarvebasin: an older one of Triassic age and another of asLate Jurassic age. The latter salt formation is described

initially as an evaporitic layer deposited during one ofthe Jurassic uplift episodes. However, seismic datacharacter suggests that it might not be autochthonoussalt and could be allochthonous salt sourced from theTriassic. Salt is also distributed differently throughoutthe basin: the Triassic salt extends over nearly theentire basin while the Jurassic evaporites are limited tothe central and eastern area.

Jurassic salt structures are associated either withextensional tectonics, such as salt-rollers with associ-ated listric faults, or compressional geometriesresulting from the reactivation of listric faults asreverse faults during the compressive episodes of theTertiary. Morphologically, the Triassic salt is character-ized mainly by a number of salt piercement featuresoccurring as circular salt diapirs or elongate salt ridges.Although the time of initiation of salt movement can-not be determined, final movement occurred duringMiocene time.


Salt Tectonics Comparisons Near Three Continent-Ocean Boundary Escarpments

Fainstein, RobertoNExT - UERJRio de Janeiro - RJ, Brazile-mail: [email protected]

Krueger, AnaWesternGeco/UHHouston, Texas, USA

AbstractDeep-water geophysical data acquisition and

drilling technologies have had an impact on everyaspect of the offshore petroleum industry in recentyears. Massive, non-exclusive, speculative 2D and 3Dsurveys have been conducted offshore Brazil and WestAfrica and in the Gulf of Mexico at a record pace in thelast few years and are now being followed by diversedeep-water, drilling programs. The last frontier, ultra-deep water, is being tackled, and understanding of saltarchitecture is fundamental for developing explorationplays. This study makes a comparison of three, salt-constrained, deep-water areas: the Sigsbee Escarpmentin the Gulf of Mexico, the Angolan Escarpment alongthe West Africa Congo Basin, and the São Paulo Pla-teau Escarpment along the eastern Brazilian margin.

Autochthonous salt tectonics shapes the architec-ture of the mirror image basins of the South Atlantic,such as the producing Campos basin off eastern Braziland Congo basin off West Africa. However, at the con-tinent-ocean boundaries, major fault scarps affect thesebasins with possible allochthonous salt movements

around the transition area. Deep-water, oil and gas dis-coveries have been made in a single oil play, the slope-constrained play. The major questions in both the Cam-pos and Congo basins are oil generation in the thick,syn-rift sections beneath salt, and the conduits forhydrocarbon migration through windows in the overly-ing salt. In the ultra-deep water realm, additionalvariables are imposed by overburden thickness. Hence,a clear understanding of salt architecture around faultscarps is fundamental.

Oil generation in the area of the Sigsbee Escarp-ment in the Gulf of Mexico, occurs in sediments thatoverlie oceanic crust. Hydrocarbon migration is relatedto allochthonous salt emplacement. This is a distinctphenomenon when compared with basins of the SouthAtlantic. Models of the oil plays near the SigsbeeEscarpment, compared with the escarpments of thecontinent-ocean boundaries in the South Atlantic,improve the understanding of salt behavior and provideexploration possibilities.



Evolution of Allochthonous Salt Systems During Development of a Divergent Margin: The Adelaide Geosyncline of South Australia

Dyson, Ian A.Salt Tectonics Australia ResearchP.O. Box 221 AldgateSA 5154 Australiae-mail: [email protected]

AbstractThis paper details the evolution of allochthonous

salt systems in the Adelaide Geosyncline of SouthAustralia, a divergent continental margin that devel-oped after rifting of the Neoproterozoicsupercontinent. It differs from previous studies in thatit suggests salt-sediment interaction had a great influ-ence on stratigraphic architecture of the latePrecambrian to Early Cambrian succession. This strati-graphic architecture reflects the high subsidence andsedimentation rates in halotectonic mini-basins duringdivergent margin development of the Adelaide Geo-syncline. Sedimentation can be tied to specific stagesin the evolution of the various allochthonous salt sys-tems. Lacustrine, fluvial, and evaporite facies of the riftphase, assigned to the late Precambrian Callanna andBurra groups, were deposited in salt-canopy mini-basins that were floored by shallow-water sediments.

Debris flows indicated a stage in the development ofthe divergent margin where gravity flow deposits wereassociated with marine sedimentation. The transitionphase heralded a series of marine incursions into mini-basins, climaxing in the extrusion of a very thick saltcanopy that served as a basal detachment surface forthe breakup unconformity. Overlying marine sedimentsof the late Precambrian Umberatana Group weredeposited adjacent to reactive diapirs during the pas-sive margin phase. As diapirs passed into the activestage, they separated mini-basins having counter-regional geometries. Progradation and aggradation ofthe passive margin resulted in salt-canopy mini-basinsfloored by deep-marine sediments of the late Precam-brian Lower Wilpena Group that evolved into counter-regional salt systems. Christmas tree diapirs were char-acteristic of this final counter-regional phase.



Turtle Structures Created by Extension in a Low-Salt or Non-Salt Setting

Turner, Joshua Creviere501 Westlake Park Blvd.Houston, Texas 77079, USAe-mail: [email protected]

AbstractTurtle structures are generally regarded to be the

result of passive or extensional collapse of underlyingsalt bodies. However, subsurface examples in theColumbus basin (Trinidad), onshore south Texas(U.S.A.), and offshore Golden Lane (Mexico), exhibitfour-way inversion structures that look at least superfi-cially like turtle structures that formed with little or nosalt at the detachment level. Furthermore, many anti-clines in the shelf region of the northern Gulf ofMexico are possibly more kinematically akin to exten-sional turtles than traditional turtle structures.

I propose the term ‘extensional turtle’ to denote aclass of turtle structures at the opposite end of the spec-trum from traditional turtles, where a mock turtle liesbetween. Unlike mock turtles, extensional turtles aregenerated purely by extension. Even so, they com-monly have some mobile-rock withdrawal, as they arealways associated with a very weak detachment. The

distinguishing feature of such structures is that they arebound by a kinematically linked set of regional andcounter-regional, large-offset, listric normal faults.Local complications may occur where youngerregional faults repeatedly cut the counter-regionalfault, resulting in the counter-regional fault becomingreset downdip. The counter-regional fault may thenremain active, resulting in multiple turtle anticlines.Counter-regional rollover followed by regional rolloveron opposing arcuate listric faults produces four-wayplunging turtle structures.

Offshore Louisiana has numerous turtle struc-tures, extensional faults, and salt diapirs. I suggest thatmany of these turtles bear significant similarities toextensional turtles, and it is likely that a continuum ofstructural styles exist between true turtles, mock turtlesand extensional turtles.



Relay Ramps and Lateral Ramps—Active Sediment Fairways During the Passive Margin Stage of Development of the Gulf of Mexico Basin

Palmes, Stephen L.Minerals Management ServiceNew Orleans, Louisiana

AbstractThe passive margin stage of development of the

Gulf of Mexico basin contains thick sequences ofMiocene and younger siliciclastic sediments deposited ina framework of active listric growth faults. At depth,complex structures occur, characterized by multiple lis-tric faults detaching at multiple structural levels.Between laterally adjacent fault blocks, displacement istransferred from shallower to deeper structural levelsalong lateral ramps, relay ramps, and transfer faults.These features may serve as sediment fairways, deliver-ing reservoir quality sands to deeper structural levels.Continued displacement along the same or younger lis-tric normal faults contemporaneous with deposition canposition depositional thicks on the crest of anticlinalhighs by displacing these sediments across antilistricfault bends.

Constructing 3D models and kinematicallyreverse modeling the hanging wall blocks on laterallyadjacent, linked fault systems provides a framework fordeposition of reservoir quality sand. Forward modeling

serves as a predictive tool for trap location, trap geom-etry, and the depositional extent of reservoir sands. Anunderstanding of the relative timing of structural devel-opment to the timing of fluid maturation and migrationcan reduce the economic risk of a prospect.

This study utilizes observations of 3D seismicdata sets to construct 3D conceptual models which arepalinspastically restored to the time of deposition ofreservoir sands. Observation of seismic data and result-ing 3D models yields criteria useful for the recognitionof focused deposition and subsequent deformationresulting in trap emplacement. Applying this model tothe structures lying beneath and adjacent to the Corsairand Clemente-Tomas fault systems serves as a predic-tive tool for locating sands and traps that are poorlyimaged on seismic data. This model also provides amechanism for transporting reservoir quality sands intoregions typically devoid of sands along the deeper por-tion of the Texas shelf.


Does the Frio Really Prograde in South Texas?

Cibaj, IrfanBeicip Inc.1880 S. Dairy AshfordSuite No 630Houston, Texas 77077, USA

Zaugg, PatrickTotal E&P USA800 GessnerSuite 700Houston, Texas 77024, USA

AbstractMcAllen-Pharr field is a mature, high-pressure/

high-temperature gas field in the expanded Oligocene(Frio) section south of the Norias delta system,Hidalgo County, Texas. The field has produced 1.1TCFG from a rollover anticline downthrown to thelarge-scale McAllen growth fault. Detailed studies ofthe field reveal stratigraphic and sedimentologic char-acteristics, which provide a new perspective on thedepositional history and distribution of sand within theFrio section.

The Frio Formation in the McAllen-Pharr Fieldconsists of three, thick genetic sequences, locally des-ignated the: (1) Hensley-Reichert, (2) Bond-Marks,and (3) Callavo-Card sequences. Each sequence exhib-its a vertical succession from basinal shales throughlayered sandstones to massive sandstones capped bybasinal shales. The three sequences are organized in anoverall regressive megasequence.

Within each sequence, shale intervals 200 to 500ft thick alternate with massive sandstones 100 to 300 ftthick. The transition from shales to sandstones is gen-erally very rapid and sometimes sharp; fromsandstones to shales, the transition is generally sharp.

Shales represent, in a geological time scale, the back-ground sedimentation in the basin, while sandstonesrepresent rapid deposition of coarser grained materialduring periods of catastrophic fluvial flooding. Upliftand erosion cycles of the continental interior have pro-vided the necessary sediment input whileaccommodation space is provided by expansion alongthe McAllen fault and differential compaction of sand-stone versus shale. Erosional features are observedupstream, in Vicksburg fields, upthrown to the majorFrio expansion faults, at the boundary between theVicksburg and Frio formations. These erosional fea-tures serve as pathways for sediment transport to thebasin. Consequently, the three sequences and theenclosing megasequence at McAllen-Pharr are con-trolled by tectonic activity. Each of these sequencesconsists of vertically aggrading, fan-shaped lobes ofsandstone that have formed in the downthrown blockof the expanding McAllen growth fault. Progradingtrends are observed only in parasequences at the top ofeach sandstone unit and at the top of each geneticsequence.


Cenozoic Evolution of the Northern Gulf of Mexico Continental Margin

Galloway, William E.John A. and Katherine G. Jackson School of GeosciencesThe University of Texas at Austin, Institute for Geophysics4412 Spicewood Springs Road, Bldg. 600Austin, Texas 78759-8500e-mail: [email protected]

AbstractWinker (1982; 1984) provided the first summary

overview of the depositional evolution of the Gulf ofMexico continental margin, along with a suite of crite-ria for margin recognition. The subsequent more than20 years of exploration deep drilling in the Gulf hassubstantiated both his methodology and synthesis. Thispaper updates Winker’s map and locates the paleo-con-tinental margin at the termination of 17 principalCenozoic depositional episodes (deposodes). NorthernGulf of Mexico margins are characterized by a familyof attributes, including transition from outer shelf toupper slope faunal assemblages, syndepositional exten-sional growth structures, rapid thickening alongmargin-parallel depoaxes, change from relatively con-tinuous, progradational delta and shelf to highlydiscontinuous, aggradational slope facies successions,

local development of erosional submarine canyonheads and slump scars, and increased regional dip.

Cenozoic shelf margin types include: (1) stableprogradational margins; (2) unstable progradationalmargins, typically associated with high-rates of sedi-ment supply by extra-basinal fluvial systems to largeshelf-margin deltas and their associated shore-zonesystems; (3) retrogradational margins created abruptlyby rapid sub-regional salt withdrawal, commonlyaccompanied by submarine mass wasting and erosionor slowly by long-term compactional subsidence; and(4) perched margins formed by progradation ontofoundered continental shelves. Rates of shelf edgeofflap vary greatly in both time and space along thenorthern Gulf of Mexico margin. Highest rates exceed30 km/Ma and are associated with Oligocene, middleMiocene, and Plio-Pleistocene depocenters.



The Tectonics of Tranquitas: A Field Study of Rift through Passive Margin Development and Laramide Deformation in

Triassic and Jurassic Strata of the Sierra Madre Oriental, NE Mexico

Davis, Matthew H.3605 Martin Dr.Boulder Co, 80305e-mail: [email protected]

Goldhammer, R.K.Deceased

AbstractExposed near Galeana, Nuevo Leon, are sedi-

mentary deposits and contemporaneous structures thatrecord the rifting and opening of the Gulf of Mexico,passive-margin development, and Laramide compres-sion in the region. A mapping, sedimentologic, andstructural study utilizing thin sections, measured sec-tions, aerial photos, and kinematic models hasproduced a detailed stratigraphic section that recordsthe transition from terrestrial to open-marine deposi-tion and the orientation and timing of deformationalevents. Triassic to Early Jurassic red beds in the Huiza-chal Group are composed of fluvial and marine sands.The La Boca and La Joya formations are separated by apolymictic cobble conglomerate. The Callovian MinasViejas represents the initial stages of marine transgres-sion and the overlying interbedded carbonates andevaporites of the Zuloaga and Olvido Formations weredeposited in response to cyclic eustatic sea-level fluc-

tuations. The increase of biodiversity through the upperJurassic strata reflects a change from restricted toopen-marine conditions. Rift-related tectonics andgravity driven brittle extensional features within thecarbonates have been overprinted by structures thatformed during the Laramide orogeny. The red bedshave been folded and faulted into a broad Laramideanticlinorium, in which smaller intrusion cored foldshave amplitudes on the order of tens of meters. Thedecollement for Laramide thin-skinned deformationoccurs within an evaporate unit. There is a high degreeof structural complexity in the overlying carbonates asindicated by tight folding patterns. By integrating con-cepts of depositional systems with structuraldeformation the hypothesis, “There is an exhumed pre-raft block in the Zuloaga Limestone around San Pablode Tranquitas.” will be tested.



Formation of Submarine Unconformities in Halotectonic Mini-Basins During Passive Margin Development of the Adelaide Geosyncline,

South Australia

Dyson, Ian A.Salt Tectonics Australia ResearchP.O. Box 221 AldgateSA 5154 Australiae-mail: [email protected]

AbstractSalt-sediment interaction influence the strati-

graphic architecture of depositional sequences duringthe passive margin stage of development of the Ade-laide Geosyncline in South Australia. This latePrecambrian to Early Cambrian succession outcrops inthe Flinders ranges and is punctuated by submarineunconformities. The unconformities are interpreted asdeep-water sequence boundaries that have no shallowwater equivalent. However, they can be traced laterallyinto condensed sections or major flooding surfaces.These sequence boundaries are typically overlain bydeep-water facies that reflect the high rate of subsid-

ence coupled with high sedimentation rates typicallyfound in halotectonic mini-basins. Large-scale slump-ing and canyon incision often mark the deep-watersequence boundaries. Canyon incision is associatedwith salt withdrawal or downbuilding in mini-basins.The architecture of submarine canyons is defined bythe nature and correlation of bounding surfaces, sand-stone interconnectivity and lithofacies elements. Thesefeatures are often beyond the limits of seismic resolu-tion in basins where passive margin development wasinfluenced by salt tectonics.



Exploration in Rifted Atlantic Margin Basins: New Challenges and New Ideas—Or Just Business as Usual?

Rasmussen, Bjørn A.Dreyer, TomHydro Oil and Energy Global Exploration0246 OsloNorwaye-mail: [email protected]: [email protected]

Martinsen, Ole J.Hydro Oil and Energy Research CenterN-5020 BergenNorwaye-mail: [email protected]

AbstractExploration and play types in rifted Atlantic

margin basins occur in passive margin as well as failedrift settings. Offshore Brazil and Angola, the passivemargin post-rift succession has been viewed as themost prolific, whereas in failed rift basins such as theNorth Sea basin, the pre-rift and syn-rift succession hashad the highest success rate.

In many passive margin basins, source and reser-voir rocks are separated by thick autochthonous orallochthonous salt deposits. A major challenge is tounderstand source rock deposition, maturation, andmigration of hydrocarbons: reservoir units often can beeasily imaged on seismic data. Source rock depositionwarrants new ideas, because seismic imaging belowsalt is poor. The understanding of source deposition

often relies on low-resolution data such as gravity andmagnetic data, or deep seismic data tuned towardsidentification of major structural lineaments. Thus,new play identification is clearly dependent onimproved source rock understanding.

On the contrary, in failed rifts, source rock depo-sition and migration are relatively well understood.Classic plays such as rotated fault blocks containingpre-rift reservoirs are well known and simple to iden-tify. A future challenge lies in identification of lessvoluminous reservoirs in the syn-rift and early post-riftsuccession. Such plays may add significantly to other-wise declining reserves and prolong the life of existinginstallations.





New Insights from CongoSpan Pre-Stack Depth Migrated Imaging in Angola-Congo-Gabon: Petroleum Systems and Plays

Henry, Steven G.Innovative Exploration Services, LP14451 Twisted Oak LaneHouston, Texas 77079


Danforth, AlConsulting Exploration Geologist404 Bayou Cove CourtHouston, Texas 77042

Venkatraman, SujataGX Technologies Corporation

2101 City West, Bld. 3, Suite 900

Houston, Texas 77042

AbstractA regional survey, consisting of long lines aver-

aging 350 km in a dip direction and 2,500 km in astrike direction, consisting of nearly 13,000 km of 2Dpre-stack depth migrated (PSDM) seismic data wasacquired by GX Technology over the West African saltbasins of Angola, Congo and Gabon in 2004 (Con-goSpan). This data provide the first consistentacquisition and processing from shallow water (50 m),past the limit of the salt, and into the ultra-deep water(4,000 m or deeper). These profiles are in depth, pro-viding multiple transects of the continental margin,from rifted continental crust, across the crustal transi-tion zone, and onto the interpreted drift volcanic terrainassociated with breakup of the South Atlantic. TheCongoSpan regional grid provides adequate coveragefor observing changes along both strike and dip of thecontinental margin, avoiding the pitfalls of single lineinterpretations, and affords insights into rifting processon both sides of the South Atlantic.

The advantage of the PSDM images is that theyprovide improved reflector geometry by minimizingdistortions associated with lateral velocity variationscaused by salt and water. These depth images present anew view of the crust beneath the salt and the drift vol-

canics. These improved images have been used inidentifying a consistent set of tectono-stratigraphicunits (pre-rift, syn-rift, sag, and drift), which have beencorrelated over the study area. The sag is an importantunit that developed in response to post syn-rift thermalsubsidence forming a large basin (1,200 x 200 km, and2 km thick) containing fluvial, lacustrine and possiblemarine sediments.

The base of the sag unit in the deeper parts of thebasin has been difficult to image prior to the acquisi-tion of this data, which images to a depth of 25 km.Because the sag unit contains rich source rocks cur-rently in the active oil generation window over much ofthe area, its delineation is an important constraint onmodels for the rifting of the South Atlantic. Thechange in the style of salt tectonics, from extension tocompression, appears related to sag-unit geometry andthe underlying basement structure. The structural andstratigraphic insights provided by the PSDM data aregenerating new ideas on the petroleum systems andwill be useful for developing the new plays that willcontinue driving exploration on both sides of the SouthAtlantic.



Deformation Induced Pathways for Hydrocarbon Migration Through the Aptian Salt Level in the Angolan Margin

Fort, Xavier

Hydro Consultant

12, Allée des Iles Chausey, 35700 Rennes, France


Brun, Jean-PierreGéosciences Rennes, University of Rennes 1, UMR CNRS 611835042 Rennes, Cedex Francee-mail: [email protected]

AbstractAlong the Angolan margin, the post-rift struc-

tural framework of which is strongly influenced by salttectonics, a number of hydrocarbon reservoirs that arelocated above the Aptian salt have been charged bypre-salt source rocks of lacustrine origin. The paperexamines the deformation mechanisms that can lead towindows in the salt layer able to provide pathways forhydrocarbon migration. It is shown that extension, dueto gravity driven deformation, leads to cover-basementcontacts in the sealed, tilted block sub-domain thatoccurs in the upper part of the margin. Once created,these contacts represent “permanent windows” in thesalt layer. In the neighboring rollover sub-domain, thesalt layer is also strongly thinned, but more homoge-neously, preventing the formation of cover-basementcontacts. The analysis of seismic sections shows that in

absence of direct observation (e.g., well data) activefaulting can provide extremely useful criteria to detectthe presence of salt layers too thin to be seismicallyimaged. The possibility that basement faults cuttingthrough the salt layer could provide “transient win-dows” cannot be excluded. In the Angolan margin, thesupra-salt hydrocarbon reservoirs charged by pre-saltsource rocks are mostly located in the sub-domain ofsealed, tilted blocks. As indicated by analog modeling,this domain is the most favorable for the creation ofpermanent windows in the salt layer. It is therefore sug-gested that hydrocarbon migration from pre- to post-salt sediments is strongly dependant on the significantsalt layer thinning and penetration in the sealed tiltedblock sub-domain.




Exploration Using a Linked System Approach to the Rift and Drift Sections in Brazil

Love, F. R.Stewart, D. J.Shell International Exploration & ProductionEPT-SolutionsHouston, Texas

AbstractIn the core Brazilian Campos and Espírito Santos

Basins the petroleum system is complex with post saltreservoirs and structures linked to the to the pre-salt riftbasins through salt welds, basement faults and riftgeometries. In addition, basement lineaments haveinfluenced the deepwater sand delivery system.

The primary source rocks are rift and sag sedi-ments in the Lagoa Feia Formation. Numerous giant oilfields such as Roncador and the recent Jubarte discov-ery occur along the Atlantic Hingeline where there hasbeen Lagoa Feia charge focus. Along the basin marginsthe evacuation of salt and extensional faulting providescharge access from these underlying rift sediments.Hingeline focusing is accomplished both by basementfaulting and by the taper of a sag and rift facies wedge.Salt welds within the outboard diapir provenance arealso thought to provide charge access, although thereare notable failures such as the deepwater BMC10block. Paleo-migration geometries or residual sub-seis-mic salt may have prevented charge of large BMC10four-way structures. Understanding paleo-migration

patterns, differentiating effective salt welds from non-effective welds are critical exploration elements.

Basement lineaments also influence deepwaterchannel and canyon orientation. Liniment focusedchannels are recognized as important elements in thedevelopment of the recent Espírito Santo Golfino dis-covery and in the outboard Espírito Santo Rio DoceCanyon system. With the existing 2D grid this relation-ship provides a framework for seismic faciesinterpretation. Successful exploration requires anunderstanding of the relationship between the rift andpost-salt section.

Only a petroleum system approach which incor-porates an understanding of the underlying rift sectionand the relationship to the post salt drift section can beseen to result in successful exploration.

The link between the underlying rift section andthe drift post-salt section is an important elementcharge focus and reservoir presence

The petroleum system is further complicated bythe overprint of salt tectonics on charge from the riftbasins, reservoir distribution, and structuration.


Petroleum Prospectivity of the Camamu-Almada Margin, Brazil: Insights from an Integrated Basin Analysis and Modeling Study

Bedregal, Ricardo Perez

Laboratory of Multidisciplinary Modeling of Sedimentary Basins (Lab2M)

Rio de Janeiro Federal University (UFRJ/COPPE)

Cidade Universitária – Centro de Tecnologia – Bloco I-2000 / Anexo

P.O. Box 68552 - ZIP: 21949-970 - Rio de Janeiro - RJ - Brazil


Karner, Garry David

Lamont-Doherty Earth Observatory

Columbia University

Palisades, New York, 10964, U.S.A.,

Gonçalves, Félix Thadeu Teixeira

Brito, Ademilson Fagundes

Küchle, Juliano

Filho, Elio Perez Cuiñas

Carneiro, Jason Thomas Guerreiro

Fernandes, Flávio Luís

Laboratory of Multidisciplinary Modeling of Sedimentary Basins (Lab2M)

Rio de Janeiro Federal University (UFRJ/COPPE)

Cidade Universitária – Centro de Tecnologia – Bloco I-2000 / Anexo

P.O. Box 68552 - ZIP: 21949-970 - Rio de Janeiro - RJ - Brazil

Abstract

The Camamu-Almada basin (northeastern Bra-zil), is part of the rift system formed during the EarlyCretaceous breakup of South America and Africa. Thebasin contains some small onshore gas accumulationsand two offshore oil fields. A previous study (Mello etal., 1995) characterized the occurrence of a singlepetroleum system in the Camamu-Almada basin: theMorro do Barro(!) petroleum system.

In 2003, ANP, the Brazilian National Agency forPetroleum, Natural Gas, and Biofuels, coordinated astudy on the tectono-sedimentary evolution and petro-leum potential of the basin, headed by Lab2M –Laboratory of Multidisciplinary Modeling of Sedimen-tary Basins (COPPE / Rio de Janeiro FederalUniversity). A combination of sequence stratigraphyand quantitative basin modeling techniques (Karner etal., 1997; Driscoll and Karner, 1998; Karner and-Driscoll, 1999a) was applied in order to allow a betterunderstanding of the spatial and temporal relationshipsbetween the elements and processes of petroleumsystems.

The application of sequence stratigraphic princi-ples (Vail, 1987; Christie-Blick and Driscoll, 1995) ledto the recognition of five, second-order depositionalsequences. More emphasis was given to the rift section,

which was subdivided into four, third-order deposi-tional sequences (Vail et al., 1991).

The Morro do Barro Formation comprises thicklayers of shales having high total organic carbon(TOC) content (mostly from 2 to 5%) and hydrogenindex (HI) values (up to 1,000 mgHC/gTOC), indicat-ing that these rocks are composed mainly of a lipid-rich Type I kerogen. The Rio de Contas Formation,under adequate thermal conditions, may prove itself tobe an additional hydrocarbon source.

Known petroleum accumulations in theCamamu-Almada basin are associated with structuralor structural-stratigraphic trapping within pre-rift andrift reservoirs. Most of the petroleum has been found inthe Morro do Barro Formation reservoirs (almost 75%of original volume of oil-in-place), followed by SergiFormation (around 25% of original volume) and Rio deContas Formation reservoirs.

The integration of the results achieved by seis-mic interpretation and basin modeling allowedidentification of potential exploratory targets in thebasin. Such structural, stratigraphic and combinedplays were grouped as pre-rift, rift, or post-rift.

Camamu-Almada basin potential has yet to befully confirmed. Investments in upcoming years areneeded to identify new hydrocarbon accumulations.



Basin Analysis in Brazilian and West African Conjugates: Combining Disciplines to Deconstruct Petroleum Systems

Dickson, WilliamDickson International Geosciences (DIGs)12503 Exchange Drive, Suite 510AStafford, Texas 77477e-mail: [email protected]

Schiefelbein, CraigGeochemical Solutions International (GSI)1610 Woodstead Court, Suite 200The Woodlands, Texas 77380

Zumberge, John

Geomark Research, Ltd.

9748 Whithorn Drive

Houston, Texas 77095

Odegard, Mark

Grizzly Geosciences, Inc. 14019 SW Freeway, Suite 301-735

Sugar Land, Texas 77478

Abstract

The authors have developed a technique fordefining source rock sub-basins, particularly those withlacustrine source rocks, and the limits of the relatedpetroleum systems, determining the risk of the petro-leum system processes and elements, particularly forcharge and to some extent for seal and reservoir. Thekey was learning how to integrate geophysical (espe-cially gravity and magnetic data) and geochemical datawith geologic understanding. This paper presents thedevelopment of the tools, techniques, and data setsassembled by our team with examples from prolifichydrocarbon provinces of Brazil and West Africa.

The initial work used regional gravity and mag-netic data sets (Barritt, 1993, Fairhead et al., 1997,Dickson et al., 2003a,b) to define controlling struc-tural/tectonic features, which influenced basin andsource rock development and reservoir emplacement.Sedimentary basins were re-defined from gravity data.Correlations between sediment pathways and gravitysignatures indicated redefined depocenters, largelycontrolled by the coast-parallel, syn-rift fault trend.Transfer faults, trending roughly orthogonally to thecoasts of West Africa and Brazil resulted in “piano-key-like” segmentation of the margins. These wereseen firston gravity imagery and later, along the Brazilmargin, interpreted from magnetic attributes.

Adding geochemical data, we plotted oil familiesand noticed clear separation of these families acrosssome of the coast-orthogonal transfer faults segment-ing and dividing the source rock containing sub-basins.Oils tended strongly to stay within the compartmentsdefined by the transfer faults and the coast-parallel,syn-rift fault trend and other lineations. These compart-

ments were first matched to published interpretationsof paleo-lakes. The correlation was then carried alongthe studied margins. Sub-basins correlated with cleardifferences in oil geochemistry, defining several petro-leum meso-systems (Schiefelbein et al., 2003). Moredetailed analyses, using additional data (such as pistoncores and surface slicks), within each basin revealedprobable generative sub-basins, hydrocarbon migrationpathways and barriers.

Pass-fail tests were established for various crite-ria, especially burial depth and adequacy of top seal forhydrocarbon generation and retention, respectively. Forexample, offshore Brazil, depth of burial for oil genera-tion from each source unit was correlated to sedimentthickness mapping. The maps were based on magnet-ics, using multiple depth constraints includingpublished cross-sections, surface geology, wells, andEuler deconvolution of gravity. Resulting depth accura-cies of 500 m were sufficient to determine adequacy ofpresent-day burial for the main lacustrine and marinesource rocks.

Top seal was risked by correlating gravityattributes to published salt mapping and interpretedprofiles to determine areas of near-surface disruptionof top seal. We then compared those attributes to oilgravities, piston core gas anomalies, and sea surfaceseep locations. Areas of diapir concentrations tended tocorrelate with the presence of oil slicks (from Radar-Sat) and seepage anomalies demonstrating leakage.

The outcome was a robust understanding of keyprospect risks in this region. In addition, our methodol-ogy is transportable with application to other areas,including convergent margin basins in Southeast Asia.



Petroleum Systems Related to the Equatorial Transform Margin: Brazilian and West African Conjugate Basins

Darros de Matos, Renato M.Aurizônia Petróleo LtdaNatal - RN - Brazile-mail: [email protected]

Abstract

The integrated analysis of the South Americanand African equatorial basins provide important cluesregarding the kinematic evolution of transform marginsand has important implications for the thermal and tec-tonostratigraphy history of the African and Brazilianbasins. The distribution of petroleum systems, on bothsides of the Equatorial Atlantic, was quite affected bythe tectonic history of this entire segment of the SouthAtlantic Ocean. Conventional extensional processescannot explain the kinematics and rift geometry of theEquatorial South Atlantic basins. Accepted pure-shearor simple-shear rift mechanisms, typical of divergentmargins, cannot be promptly used in basins generatedas a response to major transform motions along a conti-nental-scale plate boundary. The commonly acceptedcausal processes for rifting, such as passive/active ordiffuse/discrete rifting, cannot accommodate the SouthAtlantic Equatorial data set. Even though shearing sig-natures and pull-apart features are easily recognizedthroughout the margin, their magnitude and basinarchitecture varies significantly as a function of the dis-tance from the main transform faults. These factorshave resulted in significant differences in thermal evo-lution, tectonic subsidence, facies distribution anduplift history. The tectonic evolution of the sedimen-tary basins along the Equatorial Atlantic is betterunderstood by considering three stages: pre, syn, andpost-transform movements. These are related to kine-matic and dynamic controls provided by theemplacement of fractured swells as proto mid oceanridges, followed by the creation of oceanic crust andthe onset of transform shearing between Africa andBrazil.

The fragmentation process started as diffusemagmatic and sedimentary events, which began in lateBarremian time because of initiation of lithosphericstretching in the equatorial Atlantic, triggered by theonset of transtensional deformation. This event cli-maxed during the Aptian, when almost instantaneousextension was responsible for the widespread fractur-

ing of the Equatorial Atlantic, generating relativelywide and shallow precursory basins, but there is no evi-dence of volcanic margins or widespread developmentof typical syn-rift basins, as expected in orthogonalextensional regimes. The equatorial splitting evolvedduring the Albian-Cenomanian interval, through amulti-stage basin development, which is better under-stood if the kinematic and dynamic controls areconsidered along with the chronologic activation oftransform faults, the emplacement of oceanic crust andthe onset of drifting between Africa and South Amer-ica. The geodynamic evolution on the EquatorialAtlantic is addressed by recognizing tectonic stagesthat pre-date, are synchronous, or post-date the activa-tion of transform faults in the Equatorial Atlantic.Local tectonics and magmatism played a key role inthe “post-break-up” subsidence. The resultant basinarchitecture, facies distribution, and subsidence historyfor any particular basin vary significantly according toits paleogeographic position and to its proximity toactive transform faults. This has had major impact onthe regional distribution and the stratigraphic positionof source beds. Tectonic uplifts, varying in space andtime, also have had a major impact on reservoir distri-bution. The dynamic juxtaposition of continental crustagainst oceanic crust or spreading centers on the oppo-site side of a transform fault caused diachronousdeformations, recorded on the sedimentary record asimportant unconformities, amplified or not by synchro-nous eustatic sea level variations. The hydrocarbonshows and maturation history is quite related to thethermal history of each basin. Besides the petroleumsystems of deep-water Nigeria, where the oil-proneAptian, late Cretaceous, and Tertiary aged source rockshave been responsible for charging a quite impressiveoil province, the rest of the Equatorial Atlantic is rely-ing mainly on the facies distribution and thermalhistory of the Aptian aged source rocks to measure fail-ure and success on the equatorial margin.



The African and Brazilian margins share thesame source rocks characteristics, either proved orexpected (in deep water environments). However majordifferences arise from the tectonic sedimentary evolu-tion of each margin segment, and it is closely related to

the kinematic and thermal consequences of a complextransform margin evolution. Exploratory results fromboth sides of the Atlantic are still limited to a fewbasins, and the deep-water potential is stillcontroversial.


Laminated Lime Mudstone of the Early Oxfordian Smackover Formation of the Northern Gulf of Mexico Rim: Significance to Environments of

Deposition of Carbonate Source Rocks in Rifted Basins

Sassen, Roger

Department of Geology and Geophysics

Geochemical and Environmental Research Group

Texas A&M University

College Station, Texas 77845


Post, Paul J.

U.S. Minerals Management Service

1201 Elmwood Park Blvd.

New Orleans, Louisiana 70123-2394

Jung, WoodongDepartment of Geology and GeophysicsTexas A&M UniversityCollege Station, Texas 77843

DeFreitas, Debra A.Geochemical and Environmental Research GroupTexas A&M UniversityCollege Station, Texas 77845McDade, Elizabeth C.McMoRan Oil and Gas, LLC1615 Poydras StreetNew Orleans, Louisiana 70112

Abstract

The Late Jurassic (early Oxfordian) SmackoverFormation is a highly variable carbonate source rockfor high-sulfur oil. Short-range migration from thesource rock (lower Smackover) to adjacent reservoirfacies (upper Smackover and Norphlet) was commonand vertical migration also occurred via the peripheralfault zone and salt to reservoirs as young as Late Creta-ceous. High-sulfur oil in upper Smackover andNorphlet reservoirs was thermally cracked in place toresidual methane and non-hydrocarbon gases duringdeep burial. Study of rock and oil samples from theupdip Mississippi Salt Basin provides geochemicalinsight because of shallow burial depth and mild ther-mal stress. Paleogeography had a major effect on thesource rock. The most effective source rocks are lami-nated lime mudstones with high total organic carbon(TOC) and 100 percent algal and microbially derivedkerogen. Petrographic thin sections of the best sourcerock show that kerogen is preferentially concentratedin thick, continuous laminations separated by barrencarbonate. Interpretation of geochemistry and of thinsections suggests relative source-richness was deter-mined by the environment of deposition. Chemicalfossils (aryl isoprenoids) from extremophile bacteriashow that that some of the best source rocks were

deposited under a stratified water column. Algalblooms occurred in oxygenated top water, and organicmatter periodically settled through anoxic, sulfate-richbottom water to be concentrated in sediment-lamina-tions. Anoxic and hypersaline sediment provided anenvironment of deposition favoring extremophile bac-teria, leading to preservation of hydrogen-rich organicmatter during burial. Thermally stable diamondoidsformed in the sulfur-rich source rock at low tempera-tures (<100° C) and were later concentrated by thermalcracking of oil to gas. Study of the Smackover sourcerock shows rapid change in vertical section as well aslaterally on a scale of hundreds of meters. The degreeof variation in Smackover source rock appears to besimilar to that of Smackover reservoir facies, helping toexplain differences between Smackover oils. Otherlaminated lime mudstones from similar paleogeo-graphic settings may have generated high-sulfur oil inthe lower continental slope of the northern Gulf ofMexico, Mexico, and the Middle East. Laminated limemudstones may represent a specific source rock typeprone to early generation of high-sulfur oil in riftedsalt-bearing basins. In aggregate, this carbonate sourcerock type may have generated large volumes of high-sulfur oil.



Analysis of Pore Pressure Compartments in Extensional Basins

Williams, Kenneth E.Knowledge Systems, Inc.One Sugar Creek Center Blvd. Suite 1100Sugar Land, TX 77478e-mail: [email protected]

Madatov, Arkady G.Terra Systems, Inc.Mermansk, Russia

AbstractPressure compartments are common in sedimen-

tary basins and are the natural result of the interactionbetween a number of mechanisms generating overpres-sures in the subsurface (undercompactiondisequilibrium, hydrocarbon generation, and therelated processes of oil to gas cracking being the mostimportant ones) and the permeability-related processesthat maintain and dissipate those pressures over time.Pressure compartment boundaries within any modelledarea are commonly sub-parallel to lithology in a verti-cal sense. Changes in the permeability of the pressure-sealing sections result in differing rates of pressurebleed-off in the underlying units. In a horizontal direc-tion, faults often act as pressure compartment

boundaries. A basin modelling program has beendeveloped, allowing calibration to known pressure andporosity data through an inversion methodology andthe linking of multiple 1.5D forward models into a 3Dframework that permits the description and analysis ofthe current pressure conditions within the model. Ananalysis of the main pressure compartments in theEugene Island 330 Field area offshore northern Gulf ofMexico and in the Cassia Field area of the offshoreColumbus basin, Trinidad, shows the use of the pro-gram for identifying the sealing portions of pressurecompartment-bounding faults. An exploration strategyis outlined for the systematic identification and evalua-tion of pressure sealing fault traps.



Divergent Continental Margin Basins—The Habitat of Australian Petroleum Systems

Bradshaw, MaritaGeoscience AustraliaGPO Box 378Canberra, A.C.T., 2601, Australiae-mail: [email protected]

Abstract

More than two hundred sedimentary basins havebeen identified across onshore Australia and its off-shore marine jurisdiction (Fig. 1). These basins coverin excess of 10 million square kilometres and host agreat variety of petroleum systems ranging in age fromProterozoic to Cenozoic (Bradshaw et al., 1994; Long-ley et al., 2001.) However, more than 95 percent ofAustralia’s known reserves of petroleum are located inMesozoic and younger sediments within divergentmargin basins encircling the continent.

The majority of the initial oil reserves (3.8 bil-lion barrels of the 6.2 billion barrels of Australia’sinitial commercial crude oil reserves) were discoveredin just one of these basins, the Gippsland, located off-shore, southeastern Australia. Other significantvolumes of oil were discovered in the Carnarvon andBonaparte basins on the North West Shelf; as well asmajor gas reserves, estimated in 2004 at over 100 tril-

lion cubic feet. Australia ranked 30th and 13th in oil

and gas global reserves, and 28th and 17th in oil and gasproduction at year end 2002 (Petrie et al., 2005).

Australia’s continental margin basins are the leg-acy of the breakup of Gondwana. The character andtiming of the breakup varied along the margin and isreflected in the petroleum systems. The North Westmargin has a marine history extending back into theearly Paleozoic. Successive continental slivers riftedaway during the formation of the various incarnationsof Tethys, continuing through to the development ofthe Indian Ocean in the Late Jurassic and Early Creta-ceous. North West Shelf petroleum systems arecharacterized by marine shales providing oil sourcerocks and regional seals for fluvio-deltaic to shallowmarine sandstone reservoirs. In contrast, the late Meso-zoic breakup along the Southern Margin occurredbetween the two major continental blocks of Australiaand Antarctica. Non-marine facies characterize thepetroleum systems with coals and carbonaceous shales

sourcing the hydrocarbons trapped in siliciclasticreservoirs.

Most of the depocenters containing significantoil accumulations can be described as “failed rifts”,whether they are located on the North West Shelf or onthe Southern Margin. The major oil fields of the Car-narvon basin are located in the Mesozoic Exmouth,Barrow, and Dampier sub-basins, which lie inboard ofthe giant gas province of the Exmouth Plateau (Fig. 2).The Exmouth Plateau is a submerged continental plat-form of earliest Jurassic age and older, surrounded onthree sides by oceanic crust – the Argo Abyssal Plainto the northeast, the Gascoyne Abyssal Plain to thenorthwest, and the Cuvier Abyssal Plain to the south-west. The plateau is bounded to the southeast and eastby the oil-prone Exmouth, Barrow, and Dampier sub-basins, which are intracratonic rifts that were initiatedin the Pliensbachian.

Several kilometers of marine Jurassic sedimentswere deposited in these sub-basins that are age-equiva-lent to sections a few meters thick on the ExmouthPlateau. Breakup on the northern margin of theExmouth Plateau during the Callovian was associatedwith the formation of the Argo Abyssal Plain and pro-duced further movement on the faults bounding thesub-basins. Restricted, deep-marine environments wereestablished in the subsiding troughs, and the primaryoil source rock facies of the Dingo Claystone wasdeposited during the Late Jurassic (Bishop, 1999;Bradshaw et al., 1998; Longley et al., 2002).

A similar pattern is repeated to the north, in theBonaparte basin, where the oil-producing Vulcan sub-basin is located inboard of the Ashmore Platform(Fig. 3). In this sub-basin, Late Jurassic marine sourcerocks deposited in restricted marine troughs are the keyto the petroleum system (Edwards et al., 2004).

On the southeastern continental margin of Aus-tralia, the Gippsland basin is one of Australia’s mostprolific and mature petroleum provinces. The basin is



an intact rift preserved from the later stages of Gond-wana breakup. It was initiated as part of the east-westdirected Early Cretaceous breakup rift system betweenAntarctica and Australia. In the Late Cretaceous, theoil kitchen and main depocenter of the Central Deepwas established during renewed extension associatedwith the opening of the Tasman Sea (Bernecker, et al2001; Norvick et al 2001). The first marine incursionoccurred in the late Santonian. However, the lowercoastal plain and coal swamp facies deposited in theCentral Deep during the Late Cretaceous are regardedas the major source rocks for the billion-barrel accu-mulations of the Gippsland basin (Burns et al., 1984;Rahmanian et al., 1990).

The vast majority of Australia’s discovered oilreserves are located within rift systems in three basins– the Carnarvon, Bonaparte, and Gippsland basins. In

all three areas, the deposition of source rocks is con-trolled by rift-basin architecture. The deep-water,frontier Mentelle basin, located offshore of southwest-ern Australia, has several key features reminiscent ofthese proven oil provinces. The Mentelle basin is athick, Mesozoic, depocenter located inboard of a sub-merged continental platform, the Naturaliste Plateau(Fig. 4). Its tectonic history has some similarities to theevolution of the Gippsland basin, having been formednear the failed arm of a triple plate junction during rift-ing of Australia, Antarctica, and Australia-GreaterIndia breakup (Bradshaw et al, 2003). GeoscienceAustralia is currently undertaking number of studies inthe Mentelle basin to ascertain whether there is anyevidence of a petroleum system to compliment thisapparently promising configuration.


Systems of the Otway Basin, Southern Australia: Oil and Gas in a Complex Multi-Phase Rift Basin

Ryan, Damien

Boreham, Chris

Krassay, Andrew

Geoscience Australia

G.P.O. Box 387

Canberra, ACT, 2601

Australia


Deighton, IanBurytech Pty. Ltd.Lot 1 Warrigal Range RoadBrogo, NSW, 2550AustraliaCathro, DonnaFrogtechP.O. Box 250Deakin West, ACT, 2600Australia

Abstract The Otway Basin is a large, multi-phase rift

basin located on the Australian southern margin. Oiland gas recovered from the Otway Basin belong to theAustral petroleum supersystem and are predominatelyderived from Mesozoic fluvio-lacustrine source rocks.Based on the results of geohistory modeling and oiland gas family analysis, two main petroleum systemsare identified in the basin, the Early Cretaceous Cray-fish(!) petroleum system and the Early-LateCretaceous Eumeralla-Shipwreck(!) petroleum system.Both of these petroleum systems are classified as“known”. The symbol (!) represents the level of cer-tainty, in this case “known,” meaning that thehydrocarbons in the named source rock and the namedprimary reservoir unit have been geochemically exam-ined and found to be genetically related.

The Crayfish(!) petroleum system is mostlyrestricted to a series of syn-rift half grabens in thewestern Otway Basin. The stratigraphic and areal loca-tion of potential source and reservoirs rocks in the

Crayfish(!) petroleum system is strongly controlled bygrowth on major half graben faults. Multiple episodesof hydrocarbon charge characterize the Crayfish(!)petroleum system, with oil and gas emplaced duringthe Early Cretaceous, and a dry gas charge during theTertiary.

Hydrocarbons from the Eumeralla-Shipwreck(!)petroleum system are sourced from coaly facies devel-oped during the regionally extensive fluvio-lacustrinesag sequence that followed the first rifting phase. Thereservoir is a fluvio-deltaic lowstand sequence that wasdeposited during initiation of the second rift phase. Themajor factors influencing the distribution of theEumeralla-Shipwreck(!) petroleum system are LateCretaceous deltaic loading and Oligocene-Miocenecarbonate deposition. Favorable conditions for a recentexpulsion phase occur in the eastern Otway Basin,where a thick Oligocene-Miocene prograding carbon-ate succession overlies the relatively thin LateCretaceous succession.



The Divergent Continental Margins of the Jurassic Proto-Pannonian Basin: Implications for the Petroleum Systems of the Vienna Basin

and the Moesian Platform

Tari, GaborVanco Energy Company

Three Greenway Plaza, 12th FloorHouston, Texas 77046e-mail: [email protected]

AbstractThe present-day Pannonian basin and the sur-

rounding Carpathian Mountains occupy the riftedcontinental margin of the European plate. The MiddleJurassic proto-Pannonian basin formed in the samearea as an oceanic basin along the northern margin ofthe Tethys. Based on the latest results of the deep struc-ture of the European plate in the Bohemian Massif andthe Moesian platform segments of the European conti-nental margin, a new model of the structural evolutionof these margins is outlined.

The Bohemian Massif projects below the EasternAlps and the western Carpathians as a basement prom-ontory often referred to as the Bohemian Spur. Thissalient defines a large concave to the southeast segmentof the European margin that is interpreted as a lowerplate margin. In contrast, some 800 km to the south-east, the Moesian platform forms a convex to thenorthwest segment of the Tethyan margin beneath theSouthern Carpathian fold belt.

For the first time, the Moesian platform is inter-preted as the upper plate, conjugate margin of the

Bohemian segment of the European margin, rifted anddrifted away during the Middle and Late Jurassic. Bothmargins are classical petroleum provinces. Therefore,the pre-rift restoration has important implications forthe petroleum systems. The hydrocarbons in theVienna basin are largely sourced from the MalmianMikulov Marl deposited in a restricted basin shortlyfollowing the breakup. Similarly, the Dogger Bals For-mation is the main source rock interval in the Moesianplatform beneath the Carpathian foredeep basin.

Useful structural and petroleum systems analogsfor these continental margins are provided by otherconjugate margins; for example, the Majunga segmentof Madagascar (lower plate) and the Bur Acaba seg-ment of the Somali margin (upper plate). Anotherimportant example with similar, Middle Jurassic agefor the rifting and breakup is the northern Gulf of Mex-ico basin (lower plate) and the Yucatan microplate(upper plate).



Petroleum System and Miocene Sequence Stratigraphy: Central Sumatra Basin, Indonesia

Dawson, William C.

Almon, William R.

ChevronTexaco

Houston, Texas


Sangree, John B.Sangree Exploration Inc. Corpus Christi, Texas

CALTEX Sequence Stratigraphy TeamRumbai Sumatra, Indonesia

AbstractThe Central Sumatra basin contains the Pema-

tang-Sihapas(!) petroleum system, the most prolificpetroleum system in southeastern Asia. A chronostrati-graphic framework based on well logs and coresprovides insights concerning the occurrence of seals,reservoirs, and the distribution of hydrocarbons. Oilsourced from lacustrine lithofacies of the PematangGroup (i.e., the Brown Shale) in the underlying riftsequence migrated vertically until reaching a thickpaleosol horizon (representing the 25.5 Ma sequenceboundary). Thereafter, oil migrated toward the easternmargin of the basin charging the giant Minas and Durifields. Erosional truncation (incised valley develop-ment) of paleosols and faults provided “windows” formigration of oil into overlying Miocene (SihapasGroup) marine, sandstone reservoirs. Well log correla-tions and core data reveal the common presence ofincision along the 25.5, 22, 21, and 17.5 Ma sequenceboundaries. Oil accumulated preferentially in basaltransgressive sandstones. Approximately 80 percent ofthe recoverable oil resides in the lower part of the 21

Ma depositional sequence. These well sorted, medium-grained sandstones (Bekasap Formation) record depo-sition in estuarine (presumably macro-tidal) settings.Marine sandstones within the overlying 16.5 and 15.5Ma depositional sequences are oil-saturated; however,they are very fine-grained and have inherently low per-meability. The regional top seal for Sihapas reservoirsis formed by calcite-cemented, glauconitic shales andsiltstones (Telisa Group) that record the maximumMiocene transgression. Relatively small oil accumula-tions in the underlying alluvial-fluvial and lacustrinesandstones of the Pematang Group are sealed by paleo-sols. The permeability of the fluvial reservoirs isdegraded by poor sorting and pervasive authigenickaolinite. In distinct contrast, Sihapas sandstones haveundergone minimal diagenesis. This newly developedsequence stratigraphic framework has dramaticallyimproved the understanding of the correlation and dis-tribution of Miocene hydrocarbon reservoirs and sealsin Central Sumatran oil fields.



Constraints on the Interpretation of the Origin and Early Development of the Gulf of Mexico Basin

Post, Paul J.U.S. Department of the Interior Minerals Management Service 1201 Elmwood Park Blvd.New Orleans, Louisiana 70123-2394e-mail: [email protected]

Abstract

Numerous conceptual models (interpretations)exist for the origin and early development of the Gulfof Mexico Basin. Geophysical data (aeromagnetic,gravity, and seismic data), new concepts, and geologicdatasets (paleontologic and paleobathymetric) arerarely fully incorporated into these models, and theresult is often incomplete or inaccurate models. Thesize of the basin, a lack of lithologic control on deepstratigraphy (outcrops and well penetrations), and poorseismic imaging at depth because of the thickness ofthe post-rift sedimentary cover sequence contribute tothe diversity of concepts and models.

Constraints can be placed on the timing, architec-tural development, and control of the sedimentary fill,thereby resulting in a more concise and integrated basinmodel. For example, it must be recognized that the Gulfof Mexico Basin is part of the Central Atlantic MagmaticProvince (CAMP). Therefore, the importance of sea-ward-dipping reflectors (SDRs) in the Gulf of MexicoBasin suggests a subaerial origin for extruded “proto-oceanic” crust, thereby implying that revisions to someof the published models are necessary because of thestyle of breakup represented by seaward-dipping reflec-tors. Understanding that the edges of salt in the northernGulf of Mexico and the Campeche (Sigsbee) salt basinsdo not lend themselves to a “jigsaw” restoration for avariety of reasons, significantly affects the interpretationand timing of continental breakup. In addition, interpret-ing the presence of what may be two “breakup” events,each separating syn-rift from post-rift strata (inferredfrom seismic interpretations) in the deep-water, northernGulf of Mexico, suggests a polyphase basin evolutionprior to deposition of the thick sequence of late Meso-zoic and Cenozoic post-rift sediments. Correctidentification of the Mid-Cretaceous Sequence Boundary

on seismic datasets (aka the Mid-Cretaceous Unconfor-mity), rather than the previously misinterpreted seismicevent (recently established by paleontologic data to rep-resent the Cretaceous-Tertiary Boundary), is critical toconstraining the architecture and timing of structural andstratigraphic events. Incorporating the existence of Cre-taceous through Eocene “Oceanic Red Beds” in thedeep-water Gulf of Mexico constrains the paleobathy-metric evolution of the basin during this time, resultingin a more coherent model. Publicly released paleonto-logic data from key, deep-water wells penetrating olderstrata in the area of the U.S. offshore Gulf of Mexico,using benthonic foraminifera as paleobathymetric indi-cators, show that generally, this area deepens over time,such that the basin in the area represented by these wellsis deeper than, or as deep today as, it has ever been. Thepolyphase evolution of the Gulf of Mexico Basin, theeffects of the loading of the Mexican Cordilleran com-plex, and the occurrence of igneous dikes, sills, andflows in the northern Gulf of Mexico, often in associa-tion with salt structures, should be considered. Thechange in provenance direction estimated to occurbetween the Paleocene and the Oligocene from north-west to south has implications for many models of thebasin.

This paper points out a few constraints andissues to address in evaluating models of the Gulf ofMexico Basin and is not intended as still another modelfor basin evolution. Integrating these constraints intointerpretations of the origin and development of theearly Gulf of Mexico is extremely important since,paraphrasing Dr. Raymond Price, a model that incorpo-rates all the data and observations may not be right, butone that does not is always wrong.



Passive Margin Development in the Atlantic and Gulf of Mexico with a Special Emphasis on Proto-Oceanic Crust

Odegard, Mark E.Grizzly Geosciences, Inc.14019 Southwest Freeway, Suite 301-735Sugar Land, Texas 77478e-mail: [email protected]

AbstractSome new developments in geodynamics and

plate tectonics related to the development of continen-tal margins have occurred in the past few years that areimportant in exploring for hydrocarbons. Developmentof passive margins appears to proceed in five initialstages. First there is an initial fracturing of the crustthat is either propagation of a rift or development of therift during mantle upwelling and elevation. Second,rifting develops a zone of extended continental crusthaving large, more periodic half-graben basins. Third,faster rifting develops a zone of highly extended conti-nental crust having less well developed and lessperiodic half-graben basins. The fourth stage is the for-mation of “proto-oceanic” crust. The fifth and finalstage is the development of “true” oceanic crust.

The development and location of basins duringinitial breakup of continental plates is controlled by thelocation of zones of weakness that exist in the conti-nental crust before rifting begins. The initial directionof rifting and spreading appears to depend upon thedirection of the controlling zones of weakness. Zonesof weakness may not align exactly with the preferreddirection of spreading. During rifting and for someperiod of time thereafter, the interaction of the variouscontinental plates may not be well defined. These twofactors, and others, may contribute to development of a

forth stage after rifting and prior to the drift phasewhere the direction of spreading may be somewhatchaotic. During this phase parts of the continental crustmay be fragmented and intermingled with volcanicmaterial produced from the embryonic ridge system.Possibly other types of volcanism than mid-oceanridge basalts may occur. These factors are the basis forthe formation of the “proto-oceanic” crust described byDickson and Odegard (2000) and Odegard (2002) andrepresent the fourth phase of margin development. Thiscrust undergoes further modification as it descendsfrom its formation at or near sea level to deeper oceandepths. Finally, in the fifth phase, true oceanic crustbegins to develop.

This paper describes in greater detail the obser-vation and characteristics of the processes describedabove, particularly proto-oceanic crust. Observationsand interpretation methods are shown for various areasof the Atlantic. Finally these methods are applied to theGulf of Mexico. Using gravity data enhancements theearly location of the Yucatan Peninsula relative toNorth America is derived from the location of theboundaries between extended continental and proto-oceanic crust. This then gives insight into the rotationof the Yucatan block and the formation of proto-oce-anic crust during the opening of the Gulf of Mexico.



An Interpretation of the Crustal Framework and Continent-Oceanic Boundary in U.S. OCS of the Gulf of Mexico, Based on Gravity and

Refraction Data Analysis

Johnson, Elizabeth A.E.

Kacewicz, Marek

Unocal Exploration and Exploitation Technology

14141 Southwest Freeway

Sugar Land, Texas 77478


Blickwede, Jon F.Unocal Gulf of Mexico Exploration and Appraisal14141 Southwest FreewaySugar Land, Texas 77478

Huston, Holly H.Hunter 3-D, Inc.9898 Bissonnet #362 Houston, Texas 77036-8270

IntroductionGeophysical evidence suggests the existence of

oceanic crust in the deep-water Gulf of Mexico. How-ever, there is no consensus on the location of thecontinent-ocean boundary in this important geologicprovince. This boundary is an important constraint formodeling petroleum systems because thermal historiesare partially dependent on both crustal lithology andthickness.

A number of distinct kinematic models havebeen published for the crustal framework and early tec-tonic history of the Gulf of Mexico. All these modelswere constrained by similar seismic refraction data,tectonic subsidence analyses, global plate motions,and/or potential fields data and draw different conclu-sions on the aerial extent of true oceanic crust. Insupport of our sub-regional petroleum systems modelsfor the United States Outer Continental Shelf (OCS),we analyzed regional gravity and refraction data andconstructed a number of 2D and 3D crustal models.Our models suggest that most of the U.S. OCS isunderlain by attenuated continental crust, and that the

extent of true oceanic crust in the Gulf of Mexico maybe significantly less than many other published models.

Oceanic crust, which is newly formed crust cre-ated at a mid-ocean ridge during the drift, or sea-floorspreading phase, has distinct petrologic and geophysi-cal characteristics. In this study, we focus ongeophysical properties. Global studies of the earth’scrust (Mooney et al. 1998) show that oceanic crust isfairly consistent in thickness, velocity, and density.Crystalline oceanic crust is approximately 6 to 7 kmthick. Below a relatively thin sedimentary layer, oce-anic layer 2 is primarily pillow basalts and sheeteddikes, with an average velocity of 5.0 km/sec. Oceaniclayer 3 is composed primarily of gabbro, having veloc-ities greater than 6.6 km/sec. Oceanic crust is overalldenser (average greater than 2.8 gm/cc) than continen-tal crust (average 2.65 gm/cc). Crust underlying mostof the Gulf of Mexico has not been penetrated by drill-ing and seismic imaging is poor under areas covered byextensive salt bodies. Therefore, seismic refractiondata and gravity data are two tools used to help identifyoceanic crust.



Oceanic Crust in the Gulf of Mexico—A Combination of Rift Propagation and Slow Spreading

Calvert, StephenCowgill, MarkFugro Robertson LimitedLlandudnoNorth WalesUnited Kingdome-mail: [email protected]

AbstractThe presence or absence of oceanic crust, the

location of the continental-oceanic crust boundary, andhow spreading centers within the Gulf of Mexico areseparated from each other have been matters of conjec-ture and debate for the past 20 years and are likely toremain so for the foreseeable future.

By combining publicly available topographic,bathymetric, gravity and magnetic data and their deriv-atives, and by comparing these with analog modelsfrom divergent margins across the globe, we suggest arefined model for the opening of the Gulf of Mexico.

Rifting, leading to ocean crust formation, andseafloor spreading in this area, propagated from thewest during the Middle Jurassic, reaching the easternGulf of Mexico by the latest Jurassic/earliestCretaceous.

Many authors have suggested that oceanic crustdeveloped as far east as the Henderson and FloridaPlain protraction areas. However, we are of the opinionthat eastward from central Lund, the crust can best bedescribed as ‘proto-oceanic’ and, by using the South-west Indian Ridge as an analog, we can show that ultra-slow spreading oriented obliquely to the principal far-field extensional stress orientations, can lead to the fea-tures observed in the potential field data from theeastern Gulf of Mexico.

By incorporating the observed data into a globalplate tectonic context, we are able to confidently pre-dict the location of oceanic crust in the Gulf of Mexico,as well as the orientations of oceanic fracture zonesassociated with the opening of the basin.



The Mesozoic Opening of the Gulf of Mexico: Part 1, Evidence for Oceanic Accretion During and After Salt Deposition

Imbert, PatriceTotal CSTJFAvenue Larribau64000 PauFrancee-mail: [email protected]

Abstract Conflicting views have recently been expressed

about the deep structure of the Gulf of Mexico, asinterpretations cover the whole spectrum from oceanicto extended continental crust. The interpretation pro-posed here favors the former interpretation, as evidenceof the oceanic character is interpreted from both seis-mic (reflection and refraction) and magnetic datasets.

The core of the interpretation is the recognitionof a package of seaward-dipping reflectors (SDRs)below the Louann Salt at the base of the Floridaescarpment. Gravity and magnetic data and seismicvelocity analysis, indicate that this package of seismicevents is dense, magnetic, and has high velocities.Therefore, they are unlikely to consist of Triassic silici-clastics. Consequently, it is interpreted that theseevents correspond to the earliest stages of subaerialaccretion of volcanic crust during spreading, before theGulf of Mexico was in communication with the worldocean.

In the more distal part of the basin, the morphol-ogy of the basement on the abyssal plain is consideredas representing “classic” oceanic crust having a ridge/

transform morphology that is based on structural map-ping of seismic data.

Both the SDRs wedge and the structural trendsobserved on the oceanic crust of the abyssal plain indi-cate a spreading axis roughly trending southeast,indicating that they can be part of the same episode ofvolcanic/oceanic opening. The 50 km-wide intermedi-ate area between the SDRs wedge and the oceaniccrust in the abyssal plain, in the absence of good seis-mic imaging, is interpreted as an area emplaced byvolcanic/oceanic spreading in the same episode.

The Jurassic Louann salt overlies the SDRswedge (emplaced in subaerial conditions) and there-fore postdates the beginning of the volcanic spreadingalong the studied transect. It also overlies the interme-diate area seaward: salt deposition is thereforeinterpreted to have ended after the emplacement ofabout 100 km of volcanic/oceanic crust.

Consequently, volcanic/oceanic spreading in theeastern Gulf of Mexico started before salt was depos-ited along the studied part of the margin, continuedduring salt deposition, and ceased in the EarlyCretaceous.



The Mesozoic Opening of the Gulf of Mexico: Part 2, Integrating Seismic and Magnetic Data into a

General Opening Model

Imbert, PatriceTotal CSTJFAvenue Larribau64000 PauFrancee-mail: [email protected]

Philippe, YannTotal E&P USA800 Gessner, Suite 700Houston, Texas 77024

Abstract A companion paper (Imbert, 2005, this volume)

interprets the abyssal plain of the eastern Gulf of Mex-ico as an oceanic domain bounded to the northeast by avolcanic margin associated with the initial opening ofthe basin prior to the end of Louann Salt deposition.This paper explores the consequences of this interpre-tation on the opening model, at the scale of the entireGulf of Mexico.

Magnetic anomaly maps are compatible withstructural elements derived from seismic interpreta-tions and are interpreted in the deep Gulf of Mexicodomain as magnetic stripes recording the reversals ofthe magnetic field of the earth during the opening ofthe Gulf of Mexico. This interpretation allows us toclosely define the successive stages of opening.

This interpretation is tested against one potentialmajor time line, the seaward limit of deposition of theJurassic salt. This limit is observed in two domains; the

Louann salt in the north and the Campeche and associ-ated salt basins in the south. It is impossible to imagethe initial depositional limits of the salt due to the lim-its of seismic visibility. The proposed reconstructionimplies a depositional limit of the salt some 100 kminward of the Sigsbee escarpment to avoid overlap.Modeling shows that syn-opening flowage of the saltafter the end of evaporitic conditions, under the com-bined effect of gravity and thermal subsidence of theyoung oceanic crust, could lead to this order of magni-tude of salt displacement. This would also explain whythere appears to be more early extension than compres-sion in several areas of the Gulf of Mexico: part of thecompression has been absorbed by salt flowage onopening crust (i.e., intra-salt and cryptic).

A general reconstruction of the early stages ofopening of the Gulf of Mexico is proposed under thesehypotheses.



Regional Geologic and Geophysical Observations Basinward of the Sigsbee Escarpment and Mississippi Fan Fold Belt, Central Deep-Water

Gulf of Mexico: Hydrocarbon Prospectivity and Play Types

Roberts, MichaelHollister, ChrisYarger, HaroldWelch, RhondaChevron1500 Louisiana StreetHouston, Texas 77002e-mail: [email protected]

Abstract While most interpretations of the origin of the

Gulf of Mexico basin involve rifting by counter-clock-wise rotation of the Yucatan block, the exact placementof the ocean-continent boundary has remained contro-versial. Published interpretations (Bird et al., 2005)usually place the boundary near the basinward limit ofautochthonous salt. Our interpretation, outboard of saltand southeast of the Mississippi Fan Fold Belt, sug-gests a more complex assemblage of crustal elements.

Seismic interpretation and potential field modelingindicate a zone of highly extended transitional crustdominated by oceanic material although containinglarge, discreet fragments of continental crust. Thisdomain of anomalous, crustal material displays evi-dence that emergent to shallow marine conditionslasted longer than currently published interpretations.We believe this area supports a multitude of potentialhydrocarbon play types.



Progradation and Retrogradation of the Libyan Shelf and Slope, North African Continental Margin

Fiduk, Joseph C.

CGG Americas, Inc.

Houston, Texas, USA


Gibbs, Peter B.

Wealden Exploration

Smarden, Kent, UK

Brush, Eugene R.

Anderson, Lynn E.

Schultz, Thomas R.CGG Americas, Inc.Houston, Texas, USASchulz, Steven E.Occidental Oil & Gas Corp.Houston, Texas, USA

AbstractWith the lifting of economic sanctions, western

companies have come back to explore for hydrocar-bons in Libya, onshore and offshore. However,virtually no modern marine seismic data has beenacquired over the past twenty-five years to assist in thisrenewed exploration effort. During the past year, new2D pre-stack time migrated seismic data has beenacquired and used to examine the large-scale structuraland depositional features of the Libyan shelf and slope.The data cover approximately 38,000 line kilometers inwater depths ranging between 15 to 2200 meters.

The present day Libyan shelf margin has ademonstrably progradational character. Thick, laterallyextensive deltaic deposits dominate the shallow shelfand upper slope. These deposits display classical clino-form geometries that suggest multiple phases ofprogradation during the past 3-5 Ma. Seismic resolu-tion within the clinoform packages is high, as growthfaulting, distributary channels, slump scars, and rotatedblocks within the delta front are readily visible.

Clinoform geometries visible below, but trun-cated by, the Messinian unconformity indicate that the

early to middle Miocene margin of Libya was also pro-gradational at certain times.

Recent deltaic deposits sit upon and within adeeply eroded and scarred paleotopography, suggestinglarge-scale retrogradation of the shelf margin. The ero-sional surface extends for nearly 500 km along strike inthe Sirt Embayment. A 65 km long portion of this ero-sional surface displays high relief truncated strata,healed fault scarps, and related deep-seated faults. Inthis area it is likely that a very large volume of shelfmargin strata is missing.

The Libyan margin is tectonically active todayand has been through most of the Cenozoic. Manyfaults penetrate from deeply underlying Mesozoicstrata to the ocean bottom. The close association ofactive faults scarps, truncated strata, a potentially largemissing section, and a laterally extensive erosionalunconformity combine to suggest the possibility of cat-astrophic margin failure. The exact timing of marginretrogradation is uncertain at present but erosional rela-tionships hint that margin failure occurred eithercoincident with or following the Messinian salinitycrisis.



The Importance of Glacio-Hydro-Isostasy Within the Late Quaternary/Holocene Sea-Level History of the Gulf of Mexico:

Lessons for Stratigraphic Correlation

Simms, AlexBoone Pickens School of GeologyOklahoma State UniversityStillwater, Oklahoma 74074e-mail: [email protected]

Publisher’s note: The GCSSEPM Foundation has been sponsoring student research for several years. We havetold the students that we would be pleased, when they are done, to present their work at one of our researchconferences. The following work represents the results of one of these sponsorships. Alex did his work atRice University and we are pleased that he will present his work at a poster session.

AbstractA 30 m discrepancy between sea-level records

within the Gulf of Mexico and other “global” recordshas been known in the literature for over 50 years.Many hypotheses have been proposed to explain thisdiscrepancy including sedimentary loading due to theMississippi River and the effects of radiocarbon reser-voirs. Using quantitative numerical models and over 50new radiocarbon dates obtained from shallow marinesystems across the Gulf of Mexico, we test severalhypotheses that might explain this discrepancy. We

found that glacio-hydro-isostasy, changes in the Earth’sshape due to the shifting of mass on the Earth’s surfacecaused by the waxing and wanning of the last great icesheets, with an appropriate ice model for the Lauren-tide Ice sheet provides the best solution. Furthermore,this work has important implications for the ice sheetreconstructions for the Laurentide ice sheet and tradi-tional sequence stratigraphic methods for correlatingstrata on passive continental margins.


A-125th Annual Bob F. Perkins Research Conference: Petroleum Systems of Divergent Continental Margin Basins

Author Index

AAllen, Richardson B. 10Almon, William R. 45Anderson, Lynn E. 53

BBarbosa, Valéria C. F. 22Beaumont, Christopher 5Bedregal, Ricardo Perez 35Blickwede, Jon F. 48Boavida, Joaquim 12Boreham, Chris 43Bosworth, William 16Bradshaw, Marita 41Brito, Ademilson Fagundes 35Brun, Jean-Pierre 33Brush, Eugene R. 53Burke, Kevin 16

CCALTEX Sequence Stratigraphy Team 45Calvert, Stephen 49Campobasso, Silvia 19Carneiro, Jason Thomas Guerreiro 35Cathro, Donna 43Christensen, Chelsea 10Cibaj, Irfan 27Cowgill, Mark 49

DDanforth, Al 32Darros de Matos, Renato M. 37Davis, Matthew H. 29Davison, Ian 10, 21Dawson, William C. 45de Brito, Mateus 12DeFreitas, Debra A. 39Deighton, Ian 43Dickson, William 13, 36

Doré, A.G. 1Dreyer, Tom 31Dyson, Ian A. 24, 30

EEnachescu, Michael 7

FFagan, Alphonsus 7Fainstein, Roberto 23Ferguson, Renee 7Fernandes, Flávio Luís 35Fiduk, Joseph C. 53Filho, Elio Perez Cuiñas 35Fort, Xavier 33Fragola, Daniele 19Funck, Thomas 6

GGalloway, William E. 28Gibbs, Peter B. 53Goldhammer, R.K. 29Gonçalves, Félix Thadeu Teixeira 35Guerra, Marta Cardoso de Melo 20

HHardy, Victoria 7Henry, Steven G. 32Hermeston, Steven A. 10Hogg, John 7Hollister, Chris 52Huismans, Ritske S. 5Huston, Holly H. 48

IImbert, Patrice 50, 51

A-2 Author Index

J

Jeronimo, Paulino 12Johnson, Elizabeth A.E. 48Johnson, Markes E. 15Jung, Woodong 39

K

Kacewicz, Marek 48Karner, Garry David 35Kearsey, Stephen 7Krassay, Andrew 43Krueger, Ana 23Küchle, Juliano 35

L

Lau, Helen 6Ledesma-Vázquez, Jorge 15Louden, Keith 6Love, F. R. 34Lundin, E.R. 1

M

Madatov, Arkady G. 40Martinsen, Ole J. 31Massimi, Paolo 19Matias, Hugo 22Matias, Luis 22McDade, Elizabeth C. 39Menezes, Paulo 22Mohriak, Webster U. 13, 18Molnar, Jim 9

N

Nemcok, Michal 10

O

Odegard, Mark E. 13, 36, 47

P

Palmes, Stephen L. 26Peliganga, Jose Manuel 12Pequena, Monica 20Philippe, Yann 51Post, Paul J. 39, 46

R

Rasmussen, Bjørn A. 31Roberts, Michael 52Rosendahl, B.R. 13Ruffo, Paolo 19Ryan, Damien 43

S

Sandnes, Frode 22Sangree, John B. 45Santos, Fernando 22Sassen, Roger 39Schiefelbein, Craig 36Schlische, Roy W. 11Schultz, Thomas R. 53Schulz, Steven E. 53Scrofani, Giovanni 19Segall, Marylin P. 10Sibuet, Jean-Claude 7Simms, Alex 54Spadini, Giacomo 19Srivastava, Shiri 7St. John, Bill 17Stewart, D. J. 34Stuart, Charles 10Szatmari, Peter 20

T

Tari, Gabor 9, 44Thompson, Tim 7Turner, J.P. 13Turner, Joshua Creviere 25

A-325th Annual Bob F. Perkins Research Conference: Petroleum Systems of Divergent Continental Margin Basins

VVågnes, Erling 12Venkatraman, Sujata 32

WWelch, Rhonda 52Williams, Kenneth E. 40Withjack, Martha Oliver 11Wu, Jack 6

YYarger, Harold 52

ZZaugg, Patrick 27Zumberge, John 36

A-4 Author Index

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