Model Prediction of the Influence of Fault Slip, Sediment Yield and Water Level Histories on Stratigraphy in Extensional Basins

Martin A. Perlmutter, Elizabeth A. Lorenzetti, Philip D. Moore, Christopher G. St. C. Kendall

We examine the influence of fault slip, sediment yield and water level histories on the stratigraphy of extensional basins by using a basin simulation program that integrates models that individually simulate the structural and stratigraphic elements of basin formation. A computer program that models extensional structures using fault-related folding concepts developed by Xiao and Suppe (1992), is used to provide the kinematic fault slip history to Sedpak, a parametric program developed at the University of South Carolina that outputs stratigraphic architecture.

A synthetic basin is modeled as a half-graben, with motion on a single, listric border fault. Basin fill is assumed to be siliciclastic lacustrine or marine deposition occurring concurrent with fault motion. End-member scenarios are evaluated for combinations of variables including rapid and slow subsidence rates, wide and narrow extension, rapid, slow and cyclic sedimentation rates, and stable and oscillatory water level.

Evaluation of the simulations demonstrate that tectonic and stratigraphic processes can be estimated well enough to assist in interpretation of stratal geometries from seismic data. End-member scenarios can therefore be used to provide keys to structural and stratigraphic histories. However, simulations also show that similar geometries are not necessarily produced by similar processes. Various input combinations can produce similar results that represent different basin form and fill histories. The prediction or inference of lithologic distribution based on interpretation of geometry can therefore be greatly affected by the combination of earth processes that are modeled. As an example of the model's utility, output, was tuned to match an interpreted seismic section.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995