Himalayan foreland

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Himalayan foreland Foreland basins .geos.ed.ac.uk/homes/mnaylor/Links.html

description

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

Transcript of Himalayan foreland

Page 1: Himalayan foreland

Himalayanforeland

Foreland basins

www.geos.ed.ac.uk/homes/mnaylor/Links.html

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Collisional mountain belt

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Flexure of beams

Infinite Semi-infinite

Forebulge

Accommodation space(Hole)

Pinchoutpoint

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Flexure of the lithosphere

M0

Amount of flexure

4/14

img

D

Flexural parameter

x

MVx

MD

exw

x

cossin2

)( 000

/2

Flexuralrigidity

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Basin types – Ocean-arc boundary

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Basin types – Orogenic belts

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Taiwan

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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)

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Early analysesSystem simulated by a tapered wedge overthrusting an elastic beam with surface redistribution

by diffusion (Flemings & Jordan 1989; Sinclair et al., 1991)

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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

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Taiwan

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Taiwan

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Chronostratigraphy

time

distance distanceOnset of

orogenesis

growth

Steady-statetime

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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

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Thrust propagation consumes

foreland basin

(D. Garcia-Castellanos et al, 1997)

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Price 1973

Flexural Basin Concept

Flexure

ThrustingForeland basinPinchout point

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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)

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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)

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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

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