--> Numerical Modelling of Growth Strata Associated with Thrust Related Folding, by J. Poblet, S. Hardy, D. Waltham, and K. McClay; #90986 (1994).

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Abstract: Numerical Modelling of Growth Strata Associated with Thrust Related Folding

Josep Poblet, Stuart Hardy, Dave Waltham, Ken McClay

Previous numerical modelling of growth strata associated with thrust related folds has included simple models of sedimentation. In particular, local erosion, transport and sedimentation as a result of uplift and rotation has not been addressed and erosion has often been treated as the loss of material above a base level.

In addition, a considerable number of folds exhibiting limb rotation indicated by growth strata with wedge geometries ("progressive unconformities") have been found. However, the kinematics of the geometric models of fault-bend and fault-propagation folds proposed up to now assume constant dip of the forelimbs and therefore do not account for such wedge geometries.

To investigate growth strata associated with fault-bend, fault propagation and detachment folds, a tectono-sedimentary forward modelling equation has been used (Waltham 1992). A velocity model of deformation is firstly derived from Suppe and Medwedeffs' equations and from our own equations in the case of folds displaying limb rotation. Models of background sedimentation and local erosion, transport and deposition are then added to these velocity models of deformation. For each type of folding, syn-tectonic sediment geometries in sub-marine and sub-aerial environments are modelled and are contrasted with the geometries observed in natural examples. The integration of field data with the numerical models has proved to be an invaluable tool in understanding the structural evolution of th ust/fold structures.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994