IV – OTHER TYPES OF BASINS

Transcription

1-Strike-slip basins
2-Cratonic basins
3– Late orogenic basins
and more…
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Master1 Réservoirs Géologiques Dynamique des Bassins - Michel Séranne
IV – OTHER TYPES OF BASINS
1- Strike-slip Basins
Woodcock 1986
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Tectonic setting of strike-slip faulting
Seismic examples of stike-slip faults
«!Flower
structure!»
Reverse fault
component
of mvt.
Growth structures
+unconformiies
Sub-vertical fault
Offshore California
-! difficult to image in seismic (sub-vertical feature)
-! evidence of deformation of surrounding sediments
-! evidence of vertical components of movement
(unconsistent normal or reverse fault)
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Normal fault
component
of mvt.
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Altyn-Tagh strike-slip fault and associated basins
Strike-slip structures in maps
Opposite block moves
towards the right
Christie-Blick et al, 1985
Allen & Allen, 2005
Stress distribution in a
releasing overstep (pullapart basin). Note
extensional structures
in the overstep and
compression outside, at
the fault tip.
Opposite block moves
towards the left
Guiraud & Séguret 1986
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Left-lateral
Compressional
Extensional
Resleasing bend Restraining bend
Right-lateral
Low-angle and oblique to
bounding faults = extensional
High-angle and // to major
bounding faults = Strike-slip
Unconformities : jumps of faults activity
Aragon & Martin 2007
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Structure of strike-slip basin: Northern Gulf of California
Strike-slip basins : Lithosphere structure
Transverse section
Longitunidal section
extension in relay
Sedimentary basins in extensional relay zone,
between strike-slip faults
-! extensional faults => rift features
-! stretching parallel to strike-slip faults
Pull apart Basin
Rm:
Transpression = strike-slip + compression
Transtention = strike-slip + extension
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Relay zone
Deformation patterns in
model m2.2.1 after 100 km
of strike-slip displacement
in the sections crossing the
central part of a pull-apart
basin parallel to the faults
(A), perpendicular to the
faults (B), and in horizontal
cross sections in the upper
crust (C), in the lower
crust (D), and in the upper
mantle (E). The
deformation pattern is
changing from "classical"
pull-apart type of
structure (as shown in Fig.
1A) in the upper crust to
the diffuse shear zone in
the mantle, with the
transition pattern in the
lower crustal detachment
zone
Petrunin & Sobolev, Geology 2006
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Strike-slip basins : Lithosphere deformation
Deformation above a decollement (thrust nappe)
!! no thermal effect
!! average heat flow (+/- 60mW/m2)
!! Vienna Basin
Deformation affecting the entire lithosphere
!! important, localised thermal effect
!! High heat flow (80-120 mW/m2)
!!Salton Trough
Allen & Allen, 2005
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Thin-skinned vs lithosphere structure
Subsidence of strike-slip basins
Subsidence curve of
typical strike-slip basins
(compared to other types of basins)
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Wu & al , 2009
Subsidence origin :
• vertical component on SS & normal faults
• reduced thermally-driven subsidence
=>Thin-skinned SSB: No lithospheric thinning
=> Thick-skinned SSB : Fast cooling
(by lateral heat loss)
• Rm: frequent inversion (switch of active segments
within a broad wrenching zone)
Sedimentation model
Axial drainage
Sabkha
Wide alluvial fans on inactive border
Narrow & steep alluvial fans along active faulted border
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Death Valley, Ca.
Strike-slip movement
=> lateral migration of
sedimentary sources & depocentres
•Wrenching zone => several juxtaposed SSB separated by uplifted areas
=> Individual basins difficult to correlate
•Syntectonic sediments (all. fans, progr. unconf., rapid facies change)
Steel, 1988
Link &Osborne, 1978,
Crowell & Link 1982
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Sedimentation pattern in strike-slip basins
2- Intra-cratonic Basins
Cratonic Basins: Michigan Basin -> old rift ???
Cretaceous
Carboniferous
stratigraphy
100km
Precambrian
Keweenawan rift
outcrops
Ordovician
Iospachs (1000ft)
Precambrian
Keweenawan rift
(positive gravity
anomaly)
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Geological map
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3 different hypotheses for subsidence origin
A new model for subsidence of cratonic basins ?
Extensional strain rate
Armitage & Allen, 2010
Stretching factor "#
Armitage &
Allen, 2010
Cratonic basins are part of the rift–drift
suite, occupying a portion of the existence
field at low stretch factors and low
extensional strain rate.
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water-loaded subsidence (no sediment=> no effect
of sediment load => =geodynamic subsidence) for high
strain rate (left) and low strain rate (right)
Thermal diffusion cools the upwelled asthenospheric
mantle at a rate equal to the upward advection of the
asthenosphere. Therefore when the extension is very
slow, the upwelled asthenospheric mantle cools as it
rises, and the thermal lithosphere thins less than by
instantaneous or fast extension. This counters the
buoyancy of the otherwise warmer upwelled mantle,
giving prolonged thermal subsidence.
From Moussine & al.
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Taoudenni Basin : the largest sedimentary basin in the World
3- Late-orogenic Basins
Late orogenic extensional basins
East Shetland platform: Devonian extension following Caledonian orogeny
Séranne 1988
Seguret & al. 1989
Model of late-orogenic extensional basin
Driving forces for late orogenic basins
Roll-back
Séranne 1993
e.g. : Variscan Europe
e.g. : Scandinavian Caledonides
e.g. : W. Mediterranean; Aegean
Lateral extrusion
Subsidence of all type of basins.
Compare and discuss !
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Extensional collapse
Compare and discuss !
Allen & Allen 2006
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Heat flow of all type of basins.

IV – OTHER TYPES OF BASINS

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