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ABSTRACT: Sea Level Fluctuation and Development of Miocene Growth Faults, Western Louisiana OCS

Yang Su Yeong, Joel S. Watkins, Mark M.-J. Jiang

Mapping of Miocene systems tracts suggests that sea level fluctuations triggered or controlled the development of growth faulting in the western Louisiana OCS, Gulf of Mexico. We identified Miocene systems tracts using seismic data, nannofossil data, electric logs, continuous dipmeter logs, and synthetic seismograms, then calculated the expansion indices of each systems tract at major growth faults. The lowstand systems tract, consisting of coarse-grained lowstand fans and a thick lowstand wedge, shows considerable thickening on the downthrown side of the fault. Paleobathymetry data and isochron maximum locations indicate that the paleoshelf edge coincides with the outcrop of the growth fault that has the greatest rate of expansion.

In our model, thick lowstand fan and wedge sediments load the upper slope, causing failure and faulting near the shelf edge. After inactivity or minor faulting during transgression, the growth faulting reactivates with the progradation of highstand deltaic sediments. New growth fault systems develop near the new paleoshelf edges during subsequent lowstands.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990