SARZALEJO, SABRINA, J. B. ANDERSON, K. COTERILL, and P. R. VAIL, Rice Univ., Department of Geology and Geophysics, Houston, TX; and M. LAGOE, Department of Geol. Sciences, Univ. of Texas at Austin, Austin, TX

ABSTRACT: High Frequency Cyclicity in East Texas Outer Shelf and Upper Slope Sequences Revealed by High Resolution Seismic Data and Platform Borings

The effect of glacio-eustatic fluctuations on the distribution of late Quaternary deposits of the outer shelf and upper slope of the East Texas continental margin is being investigated. Approximately 1660 km of high-resolution seismic reflection data and over one hundred platform boring descriptions comprise the basic data set. In addition, samples and gamma-ray logs of a few key platform borings, as well as lithologic descriptions, logs and paleontologic information from upper slope cores, are being examined. Sequence stratigraphic techniques, combined with radiometric dates are used to relate sequences to the oxygen isotope curve, the proxy eustatic curvefor the late Quaternary. The resolution of the seismic data (0.5-1 m) permits the recognition of stratal patterns and geometries w th

great confidence.

The most striking features observed in the region are shelf margin deltas that display clear cyclicity and a signature of lowstand deposition. These deposits show a complex pattern of progradation and aggradation that varies throughout the area. This complexity is associated with salt movement and associated growth faulting. The data show evidence that salt tectonics are the dominant control on the location of feeders and depocenters, as well as the accommodation space available for deposition. Conventional seismic records show an overall progradational character, but the complexity within a single systems tract is not discernable beyond the gross pattern. High-resolution seismic data can image the building blocks of systems tracts and sequences and thus constitutes a valuable tool in the understanding of sequence stratigraphy.

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