--> Abstract: Coupled 3D Landscape and Sedimentary Numerical Modelling of Along-Strike Variability in Hangingwall Stratigraphy Caused by Fau; #90063 (2007)

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Coupled 3D Landscape and Sedimentary Numerical Modelling of Along-Strike Variability in Hangingwall Stratigraphy Caused by Fault Displacement and Sea-Level Cycles

 

Finch, Emma1, Rob Gawthorpe1 (1) University of Manchester, Manchester, England

 

We apply a three-dimensional model of landscape evolution and clastic sedimentation to investigate the effect of normal fault displacement and cyclic sea-level change on the along-strike variability of depositional sequences in rift basins. Sediment is eroded from the hinterland through a stream-power incision law and deposited in the basin using a modified diffusion algorithm. During the initial stages, erosion of the hinterland is driven purely by fault displacement, resulting in streams with the greatest incision and headward erosion being observed at the location of maximum fault displacement with less noted at the fault tips. Accommodation space is greatest at the centre of fault, however, so the progradation of deltas into the basin is generally greater towards the tips. A cyclic sea-level change is then introduced using a sinusoid with varying amplitude and wavelength, permitting investigation of the effects of relative ‘fast' and ‘slow' changes in accommodation space. In most cases, the initial sea-level fall results in incision across existing deltas, more rapid incision in the footwall is noted with greater rates of displacement and sea-level change. During sea-level fall, capture of existing channel networks from previously isolated streams is not uncommon. The stratigraphy developed during sea-level rise is strongly influenced by the incised valley system developed during the preceding fall. These models show that important controls on the along-strike variability of stratigraphy associated with displacement on normal faults can be caused by both the rate and amplitude of relative sea-level change and sediment supply from evolving drainage networks.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California