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Mechanisms of crustal Mechanisms of crustal subsidence subsidence Sedimentary basins Sedimentary basins Isostasy Isostasy Basins due to stretching Basins due to stretching Basins due to cooling Basins due to cooling Basins due to convergence Basins due to convergence Basins due to tearing of crust Basins due to tearing of crust

Mechanisms of crustal subsidence Sedimentary basins Isostasy Basins due to stretching Basins due to cooling Basins due to convergence Basins

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Page 1: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Mechanisms of crustal subsidenceMechanisms of crustal subsidence

Sedimentary basinsSedimentary basins IsostasyIsostasy Basins due to stretching Basins due to stretching Basins due to coolingBasins due to cooling Basins due to convergenceBasins due to convergence Basins due to tearing of crustBasins due to tearing of crust

Page 2: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 3: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Principles of isostasy

Page 4: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 5: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Hawaiin seamount chain with flexed lithospheric lows

Page 6: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 7: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Basins due to stretchingBasins due to stretching

Page 8: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 9: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Mantle plumes associated with rifting – not required, but do occur e.g. North Atlantic rifting and emplacement of Tertiary igneous province

Page 10: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 11: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Half-graben formation during rifting

Page 12: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 13: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Faults, lakes and volcanoes dominate the landscape

Page 14: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Lakes filling half-grabens with thinned lithosphere generating heating and volcanism

Page 15: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Basins due to thermal Basins due to thermal subsidencesubsidence

Page 16: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Basins due to thermal subsidence after heating following rifting– passive margins

Page 17: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Typical form of a passive margin

Page 18: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Passive margin accumulates thick sediment that drapes the continent/ocean transition.

Subsidence is slow and exponentially declines as cooling of rifted lithosphere slows.

Page 19: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 20: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Basins due to Basins due to convergenceconvergence

Page 21: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Crustal depressions due to loading during subduction – accretionary trench

Page 22: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 23: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 24: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 25: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Basins due to loading of continental lithosphere – Foreland Basins

Page 26: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 27: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 28: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 29: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Basins due to tearing – Basins due to tearing – strike-slip basinsstrike-slip basins

(pull-apart)(pull-apart)

Page 30: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins
Page 31: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

San Andreas Fault

Page 32: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

Basins due to tearing of crust – strike-slip basins

Page 33: Mechanisms of crustal subsidence  Sedimentary basins  Isostasy  Basins due to stretching  Basins due to cooling  Basins due to convergence  Basins

SummarySummary

Sedimentary Basin form by a number of Sedimentary Basin form by a number of meansmeans

Lithosphere can stretch (Lithosphere can stretch (Rift basinsRift basins)) Cool and subside (Cool and subside (Passive marginsPassive margins)) Be loaded and bend (Be loaded and bend (accretionary trenchaccretionary trench

on oceans – on oceans – Foreland basinForeland basin on continents) on continents) Tear apart to form Tear apart to form pull-apart or strike-slip pull-apart or strike-slip

basinsbasins.. Isostasy is criticalIsostasy is critical