--> Abstract: The Effects of Thermal Feedback Mechanisms During Continental Extension, by C. N. Willacy, D. A. Waltham, and K. R. McClay; #90987 (1993).

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WILLACY, C.N., D. A. WALTHAM, and K. R. McCLAY, Fault Dynamics Project, Geology Department, University of London, Egham, Surrey, England

ABSTRACT: The Effects of Thermal Feedback Mechanisms During Continental Extension

Two dimensional thermal evolution of continental rift systems has been simulated using computer models. The models are constructed using a finite difference scheme allowing the simultaneous modelling of inter-related processes. Programming philosophy is sufficiently general to permit varied distributions of brittle and ductile deformation within the lithosphere. The models include sedimentation, tectonic and isostatic adjustments; temperature and rheological response of the lithosphere during and after rifting. Temperature conduction from lower lithospheric upwelling and perturbation across major crustal faults greatly influences the architecture of rift basins and the sediments deposited within them. Thermal feedback mechanisms operate in the crust in the following ways.

Temperature hardening directly below the fault produces more brittle crust in this area. As a result the fault surface becomes detached from the brittle/ductile transition. A regional stress field still remains and the fault propagates downwards until it reaches the transition once more. Also, by altering the temperature structure of the lithosphere, isostatic compensation produces variations in the syn- and post-tectonic sedimentation. The

effects of variable fault geometry and finite or episodic rates of stretching are also observed.

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