ABSTRACT: Patterns of Slope Sedimentation in the Late Tertiary and Quaternary, Northeast Gulf of Mexico

PULHAM, ANDY, BP Exploration, Houston, TX

Slope sedimentation during the Late Tertiary and Quaternary, northeast Gulf of Mexico, has varied in distinctive ways in response to a complex interaction of external and internal basin controls. Broad patterns of slope deposition can be recognized during specific time periods. These patterns indicate that models of slope deposition should account for the nature of sediment supply, including the presence or absence of major fluvial input, amplitude, and frequency of eustatic sea level changes and the degree of sediment interaction with shallow and deeply buried salt.

Pleistocene slope systems display a high degree of variability and include periods of canyon formation with large volumes of sediment bypass to the very deep water. Pliocene slope systems, in contrast, are closely linked to shelf margin deltas indicating sea level falls were insufficient to expose shelfal areas fully. One result of this style of sediment supply was that canyons were rare or absent. In addition, periods of Pliocene deposition resulted in a complex interaction of sediment with shallow buried salt. This in turn contributed to more limited release of sediment beyond the slope and into deeper water areas than during the Pleistocene. Miocene slope deposition exhibits features of both Pliocene and Pleistocene systems and includes periods of canyon formation and progradation f thick shelf margin deltas.

Overall, slope deposition appears highly dependent on its stratigraphic position within the basin fill as a whole. This observation

suggests that simple cyclic models are inadequate in explaining the key aspects of Gulf of Mexico slope sedimentation.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)