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Himalayan foreland. Foreland basins. www.geos.ed.ac.uk/homes/mnaylor/Links.html. Huge potential for erosion in modifying stresses is nowhere better illustrated than Himalaya; however critical taper theory only approximates outer edge of system. Collisional mountain belt. Pinchout point. - PowerPoint PPT Presentation
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Himalayanforeland
Foreland basins
www.geos.ed.ac.uk/homes/mnaylor/Links.html
Collisional mountain belt
Flexure of beams
Infinite Semi-infinite
Forebulge
Accommodation space(Hole)
Pinchoutpoint
Flexure of the lithosphere
M0
Amount of flexure
4/14
img
D
Flexural parameter
x
MVx
MD
exw
x
cossin2
)( 000
/2
Flexuralrigidity
Basin types – Ocean-arc boundary
Basin types – Orogenic belts
Taiwan
Mountain belt/foreland basin couplingInitial recognition of dependence of foreland basin on thrust geometry and growth (Beaumont, 1981; Jordan, 1981)
Subsidence =
Sea-level
Topographic load (Ltopo)
f(Ltopo
Subsurface load(Lsub)
+ Lsub
Vplate
+ f(Vplate)Vthrust =
Vthrust
dxtopo/dt
f(dxtopo/dt) + f(Vplate)
Vonlap
Vonlap = dxtopo/dt + f(Vplate)
Vplate is key determinant of foreland basin metrics
,Te)
Early analysesSystem simulated by a tapered wedge overthrusting an elastic beam with surface redistribution
by diffusion (Flemings & Jordan 1989; Sinclair et al., 1991)
Pro-peripheral foreland basin Retro-peripheral foreland basin
Geometry
Tectonic subsidence
Chronostratigraphy
time
time
distance distanceOnset of
orogenesis
growth
Steady-state
Onset of orogenesis
growth Steady-stateOnset of orogenesis
growth Steady-state
dep
th
dep
th
Naylor & Sinclair, submitted to Basin Research
Taiwan
Taiwan
Chronostratigraphy
time
distance distanceOnset of
orogenesis
growth
Steady-statetime
Mediterranean Sea
Barcelona
Bay of Biscay
(a)
`A
50 km
N
50 km
NMediterranean
Sea
Barcelona
Bay of Biscay
0 50 100 200150
3000200010000 E
leva
tion
(m)
Aquitaine Basin
Ebro Basin
Topography
Topographiccross-section
Geodynamicmodel
S N
The Pyrenees
Thrust propagation consumes
foreland basin
(D. Garcia-Castellanos et al, 1997)
Price 1973
Flexural Basin Concept
Flexure
ThrustingForeland basinPinchout point
R
)O
-2
-4
2
0
020406080100X 2.5 vert. exag.
R
O
SenteradaPoblaTrempAgerWedge-top
basins:
Boixols
MontsecSierra Marginales Morreres
Pro-peripheral basin (Over subducting slab lots of thrusting)
basement
Upper SenonianLower Cretaceous
OligoceneUpper EoceneLower Eocene (sandst.)Lower Eocene (carbonates)Palaeocene
0 50km
Foreland basin succession
Ebro Basin Aquitaine Basin
time
distance distance
time
(Retro)(Pro)
Foreland Basin Summary• Foreland basins are elongate basins located
at ocean-continent and continent-continent collision zones
• They form in flexural depressions– The flexural depression can be modelled using an
elastic beam– The growth of topography loads the beam
• The basin is bound by the thrust front and the stable craton
• The advection of the basin fill towards the mountain belt creates accommodation space
• The basin is consumed as the thrust front propagates out
www.geos.ed.ac.uk/homes/mnaylor/Links.html