WALTHAM, DAVE, and KEN R. McCLAY, Fault Dynamics Project, Geology Department, University of London, Egham, Surrey, England

ABSTRACT: Modelling Deformation Mechanisms

Velocity fields describe virtually any deformation mechanism and are denoted by u(x,z,t) for the horizontal component and v(x,z,t) for the vertical component.

Simple examples are: (1) Vertical simple shear of a hanging wall where u = constant and v = v(x). (2) Pure shear where u = a.x and v = -a.z (a is constant and x and z are the horizontal and vertical distances from the fixed point). (3) The domino fault block model where crustal extension is accommodated by rotation of internally rigid blocks. The velocity field is determined by the rotation rate, (omega), and horizontal, U, and vertical, V, translation rates.

In general, more complex velocity fields are necessary. The most successful, to date, has been to combine rotation with inclined simple shear. Such a model allows footwall deformation and complex internal hangingwall faulting to be modelled.

A major advantage is that the method can he extended to model sedimentation, thermal evolution and compaction.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.