Tectonique en extension Extension crustale et lithosphérique

9/03/11

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TectoniqueenextensionExtensioncrustaleetlithosphérique

•1‐FailleNormalesetbassinssédimentaires•2‐Rift,margeetocéan

MichelSéranneMardi8marsetmardi15mars2011

FailleNormalescontraintesetdéformation

Déformation:

Contraintes:

Extension=allongement

amincissement

σ1:vertical

σ2

σ3:horizontal

uplift

subsidence

dépôt

érosion

9/03/11

2

Faillenormalesurleterrain

Faillesnormalesvisiblessurleterrain

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3

Miroirdefaillenormale

Faillenormalesurleterrain:visioncartographique

JurassiquesupCrétacéinférieur

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Carixian

Hettangian

Late Triassic

Sinemurian"Calcareous"

Lias

"Marly" Lias

Domerian

Aalenian

Toarcien

Bajocian

Bathonian

Callovian

Kimmeridgian

Dogger

Triassic

L. Oxfordian

Portlandian

Early

Cretaceous

(Neocomian)

LateCretaceous

Berriasian

Valanginian

Lutetian

Bartonian

Priabonian

Eocene

0

0.5

1.5

2.5

1

2

3

3.5

Synthetic lithostratigraphy and tectonic evolution of Languedoc

Maastrichtian

E. EocenePaleocene

L. Rupelian

Langhian

Pliocene

Stratigraphy

Early Triassic

Variscan basement

Aquitanian

Burdigalian

Malm

E. Miocene

Pliocene

Oligocene

Lithographic

column

approx.thickness

km

mid-CretaceousErosion

Th

rust

ing

&g

row

th s

tra

ta

Gu

lf o

f L

ion

Ma

rgin

Rift

ing

Th

erm

al s

ub

sid

en

ce

break-upunconformity

Messinianerosion

Pyr

en

ea

nfo

rela

nd

ba

sin

riftingunconformity

onset of Tethyan rifting

No

rth

Te

thya

n M

arg

in

"Ba

ssin

du

Su

d-E

st"

(Te

thya

n a

bo

rte

d r

ift)

Vo

con

tian

p

erio

d

Discontinuities

E.Pyrenean unconformity

Emmersion

Re

ne

we

dsu

bsi

de

nce

Th

erm

al s

ub

sid

en

cerift

ing

gra

vita

tion

al

li

stric

fau

ltin

gin

vers

ion

Tectonics

Me

dite

rr.

de

sicc

atio

n

Fluviatile

Sabkha

Lagoonal platform

Carbonate ramp

Reef platform

Slope

Basin

Lacustrine

Alluvial fans

Alluvial fans

Alluvial fans

Fluviatile

Fluviatile

Shoreface

Gilbert-deltas

Fluviatile/lacustrine

Sedimentary

environments

bauxite

sha

llow

ing

-up

de

ep

en

ing

-up

con

tine

nta

l co

nt.

co

nt.

ma

rin

em

arin

eM

arin

e

sandstone

conglomerate

lacustrinelimestone

marl & silts

dolomite

evaporites

marly limestone

limestone

bioclasticlimestone

grainstone

Jurassiquesup Crétacéinférieur

Estimationdurejet

Carixian

Hettangian

Late Triassic


Lias

"Marly" Lias

Domerian

Aalenian

Toarcien

Bajocian

Bathonian

Callovian

Kimmeridgian

Dogger

Triassic

L. Oxfordian

Portlandian

Early

Cretaceous

(Neocomian)

LateCretaceous

Berriasian

Valanginian

Lutetian

Bartonian

Priabonian

Eocene

0

0.5

1.5

2.5

1

2

3

3.5


Maastrichtian

E. EocenePaleocene

L. Rupelian

Langhian

Pliocene

Stratigraphy

Early Triassic

Variscan basement

Aquitanian

Burdigalian

Malm

E. Miocene

Pliocene

Oligocene

Lithographic

column

approx.thickness

km


Thru

sting &

gro

wth

str

ata

Gulf o

f Lio

n M

arg

in

Rifting

Therm

al subsid

ence


Messinianerosion

Pyre

nean

fore

land b

asin

riftingunconformity


Nort

h T

eth

yan M

arg

in

"Bassin

du S

ud-E

st"

(Teth

yan a

bort

ed r

ift)

Vocontian period

Discontinuities


Emmersion

Renew

ed

subsid

ence

Therm

al subsid

ence

riftin

g g

ravitational

lis

tric

faultin

gin

vers

ion

Tectonics

Mediterr

.desic

cation

Fluviatile

Sabkha

Lagoonal platform

Carbonate ramp

Reef platform

Slope

Basin

Lacustrine

Alluvial fans

Alluvial fans

Alluvial fans

Fluviatile

Fluviatile

Shoreface

Gilbert-deltas


Sedimentary

environments

bauxite

shallo

win

g-u

pdeepenin

g-u

p

co

ntin

en

tal

co

nt.

co

nt.

ma

rin

em

arin

eM

arin

e

sandstone

conglomerate

lacustrinelimestone

marl & silts

dolomite

evaporites

marly limestone

limestone

bioclasticlimestone

grainstone

Carixian

Hettangian

Late Triassic


Lias

"Marly" Lias

Domerian

Aalenian

Toarcien

Bajocian

Bathonian

Callovian

Kimmeridgian

Dogger

Triassic

L. Oxfordian

Portlandian

Early

Cretaceous

(Neocomian)

LateCretaceous

Berriasian

Valanginian

Lutetian

Bartonian

Priabonian

Eocene

0

0.5

1.5

2.5

1

2

3

3.5


Maastrichtian

E. EocenePaleocene

L. Rupelian

Langhian

Pliocene

Stratigraphy

Early Triassic

Variscan basement

Aquitanian

Burdigalian

Malm

E. Miocene

Pliocene

Oligocene

Lithographic

column

approx.thickness

km


Thru

sting &

gro

wth

str

ata

Gulf o

f Lio

n M

arg

in

Rifting

Therm

al subsid

ence


Messinianerosion

Pyre

nean

fore

land b

asin

riftingunconformity


Nort

h T

eth

yan M

arg

in

"Bassin

du S

ud-E

st"

(Teth

yan a

bort

ed r

ift)

Vocontian period

Discontinuities


Emmersion

Renew

ed

subsid

ence

Therm

al subsid

ence

riftin

g g

ravitational

lis

tric

faultin

gin

vers

ion

Tectonics

Mediterr

.desic

cation

Fluviatile

Sabkha

Lagoonal platform

Carbonate ramp

Reef platform

Slope

Basin

Lacustrine

Alluvial fans

Alluvial fans

Alluvial fans

Fluviatile

Fluviatile

Shoreface

Gilbert-deltas


Sedimentary

environments

bauxite

shallo

win

g-u

pdeepenin

g-u

p

co

ntin

en

tal

co

nt.

co

nt.

ma

rin

em

arin

eM

arin

e

sandstone

conglomerate

lacustrinelimestone

marl & silts

dolomite

evaporites

marly limestone

limestone

bioclasticlimestone

grainstone

9/03/11

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Faillenormaleenprofondeur=sismiqueréflexion

Faillesàfortpendage

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Workshop Reports

Scientific Drilling, No. 8 September 2009 59

Workshop Reports

References

Axen, G.J., 2004. Mechanics of low-angle normal faults. In Karner, G.D., Taylor, B., and Driscoll, N.W. (Eds.), Rheology and Deformation of the Lithosphere at Continental Margins. New York (Columbia University Press), 46–91.

DeCelles, P.G., and Coogan, J.C., 2006. Regional structure and kine-matic history of the Sevier fold and thrust belt, central Utah. Geol. Soc. Amer. Bull., 118:841–864, doi:10.1130/B25759.1.

Manatschal, G., Müntener, O., Lavier, L.L., Minshull, T.A., and Péron-Pinvidic, G., 2007. Observations from the Alpine Tethys and Iberia-Newfoundland margins pertinent to the interpreta-tion of continental breakup. In Karner, G.D., Manatschal, G., and Pinheiro, L.M. (Eds.), Imaging, Mapping and Modelling Continental Lithosphere Extension and Breakup. London (Geological Society, Spec. Publ. 282), 291–324.

McDonald, R.E., 1976. Tertiary tectonics and sedimentary rocks along the transition: Basin and Range province to plateau and thrust belt province, Utah. In Hill, J.G. (Ed.), Symposium on Geology of the Cordilleran Hingeline. Denver, Colorado (Rocky Mountain Association of Geologists), 281–317.

Niemi, N.A., Wernicke, B.P., Friedrich, A.M., Simons, M., Bennett, R.A., and Davis, J.L., 2004. BARGEN continuous GPS data across the eastern Basin and Range province, and implica-tions for fault system dynamics. Geophys. J. Int., 159:842–862, doi:10.1111/j.1365-246X.2004.02454.x.

Otton, J.K., 1995. Western frontal fault of the Canyon Range: Is it the breakaway zone of the Sevier Desert detachment? Geology, 23:547–550, doi:10.1130/0091-7613(1995)023<0547: WFFOTC>2.3.CO;2.

Oviatt, C.G., 1989. Quaternary Geology of Part of the Sevier Desert, Millard County, Utah. Utah Geological and Mineral Survey Special Studies 70, Salt Lake City, Utah (Utah Department of Natural Resources), 41 pp.

Planke, S., 1987. Cenozoic structures and evolution of the Sevier Desert basin, west-central Utah, from seismic reflection data. Master’s thesis, University of Utah, Salt Lake City, Utah, 163 pp.

Sibson, R.H., 1985. A note on fault reactivation. J. Struct. Geol., 7:751–754, doi:10.1016/0191-8141(85)90150-6.

Simpson, D.W., and Anders, M.H., 1992. Tectonics and topography of the western U.S. – an example of digital map making. GSA Today, 2:118–121.

Stockli, D.F., Linn, J.K., Walker, J.D., and Dumitru, T.A., 2001. Miocene unroofing of the Canyon Range during extension along the Sevier Desert Detachment, west central Utah. Tectonics, 20:289–307, doi:10.1029/2000TC001237.

Von Tish, D.B., Allmendinger, R.W., and Sharp, J.W., 1985. History of Cenozoic extension in central Sevier Desert, west-central Utah, from COCORP seismic reflection data. AAPG Bull., 69:1077–1087.

Wernicke, B., 1995. Low-angle normal faults and seismicity: A review. J. Geophys. Res., 100:20159–20174, doi:10.1029/95JB01911.

Wills, S., and Anders, M.H., 1999. Tertiary normal faulting in the Canyon Range, eastern Sevier Desert. J. Geol., 107:659–682, doi:10.1086/314375.

Wills, S., Anders, M.H., and Christie-Blick, N., 2005. Pattern of Mesozoic thrust surfaces and Tertiary normal faults in the Sevier Desert subsurface, west-central Utah. Am. J. Sci., 305:42–100, doi:10.2475/ajs.305.1.42.

AuthorsNicholas Christie-Blick and Mark H. Anders, Department of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory of Columbia University, Palisades, N.Y. 10964-8000, U.S.A., e-mail: [email protected] Manatschal, Université de Strasbourg, IPGS-EOST, 1 rue Blessig F-67 084, France.Brian P. Wernicke, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, Calif. 91125, U.S.A.

Web Linkhttp://sevier.icdp-online.org/

AHR

GG

3.35 km

2.80 km

0

3

TERTIARY TERTIARY

PALEOZOIC

2 km

PALEOZOIC

SEVIER DESERT DETACHMENTTRAV

EL T

IME

(sec

.)

0

5

TRAV

EL T

IME

(sec

.)

10 kmA

B

Figure 3. Examples of seismic reflection profiles from the Sevier Desert basin (see Fig. 2 for location). [A] Part of COCORP Utah Line 1, with interpretation of the Sevier Desert detachment from Von Tish et al. (1985). [B] A portion of Vastar Resources, Inc. Line V-11, with interpretation modified from Planke (1987). Projected wells: GG, Gulf Gronning; AHR, ARCO Hole-in-Rock. Line V-11, located ~3 km north of the Hole-in-Rock well, is the profile that best illustrates the geological structure in the vicinity of the well.

Faillesàfaiblependage

Fig. 12. Suggested evolutionary model for the Corinth Rift. 1, Synrift deposits; 2, Parnassos Unit; 3, Pindos U.;4, Tripolis U. (a) Initial conditions, after nappe emplacement. Parnassos Unit, a Mesozoic carbonate sequence thatcrops out only north of the Corinth Rift, is the topmost nappe. (b) Early stage of rift evolution and onset of the uplift ofNorth Peloponnesus. The northern fault block is a symmetrical one, bounded from the south by the Khelmos Fault. Thesedimentation within the northern block is fed by drainage systems draining the southern, asymmetrical one, boundedfrom the south by the NorthMainalon Fault Zone (NMFZ). (c) As extension increases, the southern block becomesmoretilted, together with the Khelmos fault and new, steep hanging-wall faults develop north of it. This stage corresponds tothe second phase of the Corinth Rift evolution, where sedimentation in the northern block is characterized by giantalluvial and Gilbert-type fans. Back-tilting and antithetic faulting lead to the formation of endorheic basins on thehanging-wall of the NMFZ. (d) Present-day configuration. The NMFZ is domed beneath Mt Khelmos, with its southernpart locked (the NNW and NNE faults that truncate NMFZ cannot be seen, as they run parallel to this section). Theactive part of the detachment is confined to beneath and north of Mt Khelmos, with the north-dipping high-angle normalfaults of North Peloponnesus and the Gulf of Corinth soling onto it. Dotted line represents the actual relief. NMFZ,North Mainalon Fault Zone; KF, Khelmos Fault; TF, Tsivlos F.; VF, Valimi F.; PMF, Pyrgaki–Mamoussia F.;EF, Eliki Fault.

E. SKOURTSOS & H. KRANIS134

sheets (Tripolis and Zarouchla Complex) crop out atits relatively uplifted part. The northern boundary ofthis fault block is theKhelmosFault and all the north-andNE-dipping faults that mark the northern bound-ary of the Zarouchla Complex.

If the North Mainalon Fault Zone has a listricor ramp-flat geometry, analogous to the generallyaccepted models in various continental extensionalfields (Schlische 1991), then it should flatten at adepth of 6–8 km, underneath Mt Khelmos(Fig. 11). The deepest part of this fault may reachfurther north and merge in the postulated detach-ment zone below the Gulf of Corinth suggested byseismological and geophysical investigations (Rigoet al. 1996; Taylor et al. 2003; Bernard et al. 2006);the major normal faults in North Peloponnesus, suchas the Eliki and Pyrgaki–Mamoussia faults wouldalso sole onto this detachment (Fig. 11). This con-figuration is comparable with the existence of a low-angle normal fault at depths of 6–7 km, suggestedby Doutsos & Poulimenos (1992). It is also compa-tible with the hypocentral distributions and focalmechanisms of the earthquake sequences analyzedby Rigo et al. (1996) and Lyon-Caen et al. (2004),while it also allows for the existence of faults withlengths in excess of 10 km and with considerablecumulative displacement. The suggested detach-ment beneath the Northern Peloponnesus does notcorrespond to the Phyllite–Quartzites unit of theZarouchla Complex, but it may lie within amechani-cally weak zone of a deeper Unit of the Hellenides.

The southern part of the detachment is nowtruncated by NNE and NNW extensional faults

(Kamenitsa and Levidi faults) (Fig. 2), which arefound for at least 6–7 km within the hanging wallof the North Mainalon Fault Zone, a fact thatproves that it is no longer active, at least along itssouthern (and shallower) segment. The activity ofthe Kamensita and Levidi faults may be linked tonorthward propagation of the east–west extensionin the southern Peloponnesus, causing furtheruplift in the central and northern Peloponnesus.This extension may be due to gradual and morelocalized uplift of the Plattenkalk Unit (meta-morphic equivalent of the Ionian Unit), which ischaracterized by the formation of north–south toNNW–SSE oriented mountain chains, such asMts Taygetos and Parnon (Skourtsos et al. 2004).

Should this be the case, then the mechanicalbarrier suggested by Ghizetti & Vezzani (2005),composed of metamorphic rocks in northern Pelo-ponnesus, may not be the result of Miocene exten-sion, but the outcome of a much younger phase.

In view of the aforementioned observationsand suggestions, an alternative scenario for the evol-ution of the Corinth Rift could be given (Fig. 12),bearing in mind the ambiguity and the insuffi-ciency of data regarding crucial aspects, such asthe initial width of the Corinth Rift and the position,type and evolution of the northern margin; thesuggested interpretation assumes that this northernboundary is fixed.

The evolution of the Corinth Rift may havetaken place in two stages (e.g. Ori 1989). In the pro-posed model, the first rifting phase involved theformation of two large fault blocks: a northern

Fig. 11. Suggested geometry for North Peloponnesus and the Gulf of Corinth. According to this configuration, theNorth Mainalon Fault Zone (NMFZ) is the southernmost of the extensional structures related to the Corinth Rift.Assuming a listric or ramp-flat geometry, the NMFZ should flatten at a depth of 6–8 km, below Mt Khelmos, whileits deepest part may link to the postulated detachment zone beneath the Gulf of Corinth with the major normal faultsof North Peloponnesus soling onto it. Two major crustal blocks can be distinguished: a southern, now inactive anda northern one, which hosts the present-day seismic activity of the Rift. The distinction between upper and lowerplate does not necessarily imply difference in lithology and/or metamorphic grade (as it is common in metamorphiccore complexes). Block arrows show the suggested localized uplift driven by the northward propagation ofeast–west extension.

STRUCTURE AND EVOLUTION OF CORINTH RIFT 133

BasinandRange,COCORPChristie‐Blieck&al2009 EvolutionduriftdeCorintheetsismologie

Skourtos&Kranis2010

Faillenormales+niveaudedécollement:seulelacouverturesédimentaireestétiréeLesubstratumresteindéformé.

décollement

Faillesnormalesenracinéesdansdécollement

Substratumnon‐déformé

Couverturedéformée

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Faillecourbe=listrique

500

1000

1500

2000

2500

3000

3500

4000

4500 50

00

5500

500 1000 15

00

2000

2500

3000

3500

4000

4500

0

0

Extensional Fault

100

Borehole

Isobath (m)

Sd 101

Sd 102

Mar 9LSN 2

a) Ales Fault isobath map

0 4 Km

Sd 101

Sd 102

800

800

700

700

600

600

500

500

400300

200

100

500

400

300

900

900

800

700

600

500

400

900

1000

Mar 9LSN 2

Thrust

Cut

off

Pre-rift

Syn-rift

Extensional Fault

100

borehole

Isobath (m)

Rousson

Les Mages

Saint-Ambroix

b) Isobath map of the base Stampian

Rousson

Les Mages

Saint-Ambroix

0 4 Km

Relationentrelaformedelafailleetdubassinsédimentaire

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Sédimentationcontrelafaillependantsonfonctionnement:syntectonique

Parallèle:Déposésavantfonctionnementdelafaille

Divergent(enéventail):Déposéspendantfonctionnementdelafaille

Parallèleetrecouvrantl’ensemble:Déposésaprèsfonctionnementdelafaille

Fault

Nîmes

Petit Rhône graben

Lunel Montcalm Baumelles

NW SE

0km

2

4

6

8

10

0

2

4

6

8

10

0km

2

4

6

8

10

0

2

4

6

8

10

Vaunage

Plio-Quaternaire

La Jassette PierrefeuAubord Albaron Vaccarès

Nîmes Fault

Mioc. post-Aquit.

Aquitanien

Oligocène

Crétacé

Trias

Paléozoïque

Jurassique

GrabendeVistrenque(Camargue):Failleplaneaunorddugrabengénèreunremplissagesyntectoniquehorizontalalorsquelafaillelistriqueausudgénèreunremplissagesyntectoniqueenéventail(d’aprèsBenedicto,1996)

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X

X X'

X'2

X'1

X'2

X'1

X'2

X'1

X'2

X'1

X'X

X

b)a)

1) 1)

2) 2)

bloc supérieurbloc

inférieur

bassin

datum datum

bloc

inférieur

déformé

non déformé (translaté)

déformé


bassin

vide potentiel vide potentiel

X

X X'

X'

X'1

Géométrie des failles

d'après Faure, 1990 et Benedicto, 1996

niveau datum ousurface régionale

d

ee = extensiond = déplacement

Restauration des coupes et mesure de l'extension

footwall hanging-wall

bloc supérieur

a) b)

1 1

2 2

3 3

X'1

X''1

X'1

X''1

X'1

X''1

X'1

X''1

X'2

X''2

X'1

X''1

X'3

X''3

X'1

X''1

X'2

X''2

Géométrie du Remplissage

faille listrique faille plane

X

X X'

X'2

X'1

X'2

X'1

X'2

X'1

X'2

X'1

X'X

X

b)a)

1) 1)

2) 2)

bloc supérieurbloc

inférieur

bassin

datum datum

bloc

inférieur

déformé


déformé


bassin


X

X X'

X'

X'1




d




bloc supérieur

a) b)

1 1

2 2

3 3

X'1

X''1

X'1

X''1

X'1

X''1

X'1

X''1

X'2

X''2

X'1

X''1

X'3

X''3

X'1

X''1

X'2

X''2



X

X X'

X'2

X'1

X'2

X'1

X'2

X'1

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X

b)a)

1) 1)

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bloc supérieurbloc

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datum datum

bloc

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déformé


déformé


bassin


X

X X'

X'

X'1




d




bloc supérieur

a) b)

1 1

2 2

3 3

X'1

X''1

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X''1

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X'2

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X'3

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X'1

X''1

X'2

X''2



Faillesnormalesetbassin

‐ érosiondublocinf.etsédimentationsurblocsup.‐ déformationsyn‐tectoniquedessédiments

Géométriedesfaillesnormales

‐ Planesoucourbes‐ Fortpendageoufaiblependage‐ Affectentlesocleouseulementlacouverture

Faillesnormalesmesuredel’extensioncrustale

‐ directionextensionperpendiculaireauxfailles‐ quantitéd’extensionf(rejetdesfailles)‐ extensioncrustaledonnéeparfaillesdesocle

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USGSaerialphotographoftheregionaroundCowCanyon.ShiftingWash,amajortributarytoButlerWashtraversestheeasternsideoftheimagefromsouthtonorth.(B)Interpretationoffaultgeometries,modernstreamsandpaleo‐drainages(dashedlines)acrosstheCowCanyonarea.Priortothedevelopmentofthefaultarray,streamdrainagesransoutheasttonorthwestacrossthearea.Numberedpaleo‐drainagesillustratetheinterpretedhistoryofchannelswitchingofShiftingWash.

(B.Trudgill)

Extensionperpendiculaireauxfaillesnormales

Extensionperpendiculaireauxfaillesnormales(BasinandRange)

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Liaisondesfaillesnormales:rampeslatérales,zonesderelaiettransformantes

Strasbourg

Lyon

Grenoble

Nice

Mtp

Mar.

Valence

Bresse

Rhine Graben

Camargue

Gulf of Lion

Durance

Molasse Basin

Valencia Trough

Limagne

Saone

Normal fault

Extension direction

Isopaches of synrift sedimentation

0

1000

2000

4000

3000

100km

Valle-

Penedès

Bar.

Directiond’extensionOligocène

GolfeduLion

RiftW‐EuropéenDirectiond’extensionparanalysemicrotectonique=cohérentavecdirectiondesfaillesnormales.⇒ Faillesobliquesàl’extension?⇒ Failleshéritéesvsfaillesnéoformées

Séranne,1999

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faille

nord pyrénéenne

0 30km

ext = 4,5km

ext =7,2km

ext =10,1km

ext =4km

ext =11,8km

extension totale cumulée

direction d'extension

direction de pente des failles

valeur d'extension dans le bassin

z.t. Arlésiennez.t. C

amarg

uaise

z.t. Ardéchoise

z.t. Séto

ise

f.

f. D

uran

ce

exte

nsion

tota

le

Benedicto1996

Mesuredel’extensionencarte=variablelelongdurift=>segmentation

Directiond’extension

X

X X'

X'2

X'1

X'2

X'1

X'2

X'1

X'2

X'1

X'X

X

b)a)

1) 1)

2) 2)

bloc supérieurbloc

inférieur

bassin

datum datum

bloc

inférieur

déformé


déformé


bassin


X

X X'

X'

X'1




d




bloc supérieur

a) b)

1 1

2 2

3 3

X'1

X''1

X'1

X''1

X'1

X''1

X'1

X''1

X'2

X''2

X'1

X''1

X'3

X''3

X'1

X''1

X'2

X''2



Mesuredel’extensionencoupe

‐Modèlereliantlagéométriedelafailleetladéformationdublocsupérieurdelafaillenormale(hanging‐wall)‐Dépenddumodededéformationduhanging‐wall:cisaillementverticalouoblique‐ Extension≠rejetsurlafaille‐ Restaurationdescoupes

= 90°

= 60°

extension

extension

FailleprincipaleFaillesantithétiques(60°)=déformationdublocsup.

Fort&al2004

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13

NW SECastries type series Albaron 101 type series

Jurassic / Cretaceous

Triassic

Mesozoic Nîmes Fault

N-vergent

Pyrenean thrust

Pyrenean relief

0km

1

2

3

4

5

6

7

8

9

10

0km

1

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7

8

9

10

a)

0km

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7

8

9

10

0km

1

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8

9

10

extension 1100mextension 750m

b)Basin fill

N-Montpellier basins Petit Rhône grabenVistrenque graben

extension 1100mextension 3000m

0km

1

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4

5

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9

10

0km

1

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c) Basin fill

0km

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d)

extension 750m

Basin fill

0km

1

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10

0km

1

2

3

4

5

6

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10

e)

extension 5000m

Basin fill

rider 1

rider 2

0km

1

2

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8

9

10

0km

1

2

3

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f)

postrift tectonic movement = 500 m

pre

-Olig

oce

ne

Olig

oce

ne

Aquita

nia

npost

-Olig

oce

ne

Figure 12. Model of kinematic relationships between the low-angle basement faulted and cover

décollement domains.

1100m

3000m

750m

5000m

50m

Total9900m

Benedicto&al1996

Mesuredel’extensiondanslacouverture

Mid‐continentRift(Texas)

Mesuredel’extensioncrustale=rejetcumulédetouteslesfaillesnormaledesocle

9/03/11

14

NSDP84‐1

Fraseretal.,2003

NSDP84‐1

Moho=basedecroûte Basesédiments=Sommetdecroûte

bassin


d



Mesure de l'extension


géométrie duremplissage

Exemple Mer du Nord

l0 l

Taux d’extension = longueur finale / longueur initiale (> 1)

h0

h

Taux d’amincissement = épaisseur finale / épaisseur initiale (< 1)

l0 l

amincissement = 1 / étirement l - l0 = e

1 + e

2 + .... + e

n

50 100 250200

0

40km

150

50 100 150

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•2‐Rift,margeetocéan

ProfilsECORS‐DEKORPStructurecrustalegrabenduRhin(Illies,1977)

Riftintracontinental:leGrabenduRhin

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Rifting=étirement+amincissementdelalithosphère

CroûteCont.

ManteauSup.

1300°CAsthénosphère

Moho

Lithosphère

Étatinitial

RupturecontinentaleAccrétionocéanique

Margepassive+Océan

Contrainteextensive

Refroidissement=>subsidence

sédimentation

Manatschal&al,2001

Whitmarsh&al,2001

WestIberiaMarginContinent‐Oceantransition

Rm:peudesédimentsetpeudevolcanisme

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Afar

Margecontinentaled’Aden

Rift

Ebinger2005

Rift

Afar

Marged’Aden

Afar50km

Riftingintra‐continental=>Rupturelithosphèrecontinentale=>Accrétionocéanique

Rm:Afar:importantvolumedevolcanisme

AccrétionocéaniquedansleGolfedeCalifornie

Lizarralde&alNature,2007

Structuredelacroûtecontinentale/océaniqueVitessepropagationdesondes

Cr.continentaleCr.Océaniquesédiments

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Aprèsrifting=>drifting(dérive)=accrétionocéaniqueàlarideetélargissementdel’océan

Documents

Tectonique en extension Extension crustale et lithosphérique