Sedimentology and Biostratigraphy of Late Miocene Cores, Northern Mississippi Canyon, Offshore Louisiana, Gulf of Mexico

PULHAM, ANDY, and JULIE PEARCE, BP Exploration, Houston, TX

Recent acquisition of conventional cores in the deep-water Gulf of Mexico is increasing our ground truth tests of sedimentological and stratigraphic models of slope deposition. Nearly 400 ft of core recovered from the late Miocene in northern Mississippi Canyon has been described and analyzed for sedimentological and biostratigraphic information.

Provisional results show that in this case study sandy slope deposition comprises a wide variety of styles of gravity flow deposition. However, two distinct slope associations are clearly recognized from biostratigraphic and sedimentological signatures. The first association is characterized by relatively organized and undisturbed turbidite beds that display thickening and thinning trends but which yield little or no fauna and flora. The second association is much more irregularly bedded, has coarse-grained sands, and yields a rich assemblage of reworked and indigenous flora and fauna that identify local and regional source areas for the slope sediments.

Local seismic mapping in the area of the cores provides a structural and stratigraphic context that is similar for both slope associations. Therefore, controls on major changes in slope deposition in this case study appear to be largely external variations in the nature of sediment supply.

AAPG Search and Discovery Article #91006 © 1991 GCAGS and GC-SEPM Meeting, Houston, Texas, October 16-18, 1991 (2009)