Tectonique en extension Extension crustale et lithosphérique
Transcript of Tectonique en extension Extension crustale et lithosphérique
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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
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Faillenormalesurleterrain
Faillesnormalesvisiblessurleterrain
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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
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
Thru
sting &
gro
wth
str
ata
Gulf o
f Lio
n M
arg
in
Rifting
Therm
al subsid
ence
break-upunconformity
Messinianerosion
Pyre
nean
fore
land b
asin
riftingunconformity
onset of Tethyan rifting
Nort
h T
eth
yan M
arg
in
"Bassin
du S
ud-E
st"
(Teth
yan a
bort
ed r
ift)
Vocontian period
Discontinuities
E.Pyrenean unconformity
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
Fluviatile/lacustrine
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
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
Thru
sting &
gro
wth
str
ata
Gulf o
f Lio
n M
arg
in
Rifting
Therm
al subsid
ence
break-upunconformity
Messinianerosion
Pyre
nean
fore
land b
asin
riftingunconformity
onset of Tethyan rifting
Nort
h T
eth
yan M
arg
in
"Bassin
du S
ud-E
st"
(Teth
yan a
bort
ed r
ift)
Vocontian period
Discontinuities
E.Pyrenean unconformity
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
Fluviatile/lacustrine
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
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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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Rousson
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Saint-Ambroix
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Relationentrelaformedelafailleetdubassinsédimentaire
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Sédimentationcontrelafaillependantsonfonctionnement:syntectonique
Parallèle:Déposésavantfonctionnementdelafaille
Divergent(enéventail):Déposéspendantfonctionnementdelafaille
Parallèleetrecouvrantl’ensemble:Déposésaprèsfonctionnementdelafaille
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Vaunage
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Nîmes Fault
Mioc. post-Aquit.
Aquitanien
Oligocène
Crétacé
Trias
Paléozoïque
Jurassique
GrabendeVistrenque(Camargue):Failleplaneaunorddugrabengénèreunremplissagesyntectoniquehorizontalalorsquelafaillelistriqueausudgénèreunremplissagesyntectoniqueenéventail(d’aprèsBenedicto,1996)
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X
X X'
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déformé
non déformé (translaté)
bassin
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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)
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faille listrique faille plane
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bassin
vide potentiel vide potentiel
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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)
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faille listrique faille plane
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vide potentiel vide potentiel
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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
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Géométrie du Remplissage
faille listrique faille plane
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
non déformé (translaté)
déformé
non déformé (translaté)
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
Mesuredel’extensionencoupe
‐Modèlereliantlagéométriedelafailleetladéformationdublocsupérieurdelafaillenormale(hanging‐wall)‐Dépenddumodededéformationduhanging‐wall:cisaillementverticalouoblique‐ Extension≠rejetsurlafaille‐ Restaurationdescoupes
= 90°
= 60°
extension
extension
FailleprincipaleFaillesantithétiques(60°)=déformationdublocsup.
Fort&al2004
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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
2
3
4
5
6
7
8
9
10
a)
0km
1
2
3
4
5
6
7
8
9
10
0km
1
2
3
4
5
6
7
8
9
10
extension 1100mextension 750m
b)Basin fill
N-Montpellier basins Petit Rhône grabenVistrenque graben
extension 1100mextension 3000m
0km
1
2
3
4
5
6
7
8
9
10
0km
1
2
3
4
5
6
7
8
9
10
c) Basin fill
0km
1
2
3
4
5
6
7
8
9
10
0km
1
2
3
4
5
6
7
8
9
10
d)
extension 750m
Basin fill
0km
1
2
3
4
5
6
7
8
9
10
0km
1
2
3
4
5
6
7
8
9
10
e)
extension 5000m
Basin fill
rider 1
rider 2
0km
1
2
3
4
5
6
7
8
9
10
0km
1
2
3
4
5
6
7
8
9
10
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
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NSDP84‐1
Fraseretal.,2003
NSDP84‐1
Moho=basedecroûte Basesédiments=Sommetdecroûte
bassin
niveau datum ousurface régionale
d
ee = extensiond = déplacement
Restauration des coupes et mesure de l'extension
Mesure de l'extension
footwall hanging-wall
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