Precision Sequence Stratigraphy of the Plio-Pleistocene, Gulf of Mexico: Digital Integration of Seismic, Log, Paleontologic, and Oxygen Isotope Data

SELF, G. A., and M. L. BUTLER, Amoco Production Company Research, Tulsa, OK, and L. W. FOLSE, D. A. MAROTTA, and D. A. PRATT, Amoco Production Company, Houston, TX

An empirically based (versus a model driven) methodology was developed based on digital integration of seismic data with lithologic, paleontologic, and oxygen isotope data within a computer workstation environment. This flexibility allows the interpreter to visualize the full dynamic range of the seismic data and to manipulate both the temporal and spatial domains.

Seven depositional sequences were defined within the Plio-Pleistocene clastic section of the northern Gulf of Mexico basin, offshore Louisiana. Six of these seven sequences are associated with major falls in sea level that occurred at about 200 ka, 500 ka, 900 ka, 1.5 Ma, 2.0 Ma, 2.7 Ma, 3.0 Ma, and 4.5 Ma. Graphic correlation of oxygen isotope stages and foraminiferal climatic assemblages demonstrates that these sequence boundaries developed during third-order cool climatic stages and low sea level.

The most sand-rich section was deposited during a significant climatic warm period that developed during the middle Pliocene, prior to the onset of glaciation of the North American continent. During this period, a large delta system prograded across the shelf and deposited significant amounts of sand onto the slope. This occurred in spite of an estimated 35-m sea-level rise above present day.

Significant deposition of potential reservoir sands in the slope environment occurs during every subsequent phase of sea-level fluctuation: the result of the interaction between sea-level fluctuation, climatic variations, sedimentary processes, salt tectonics, and basin geometry. The combination of these factors causes wide variation in the timing of sedimentation, as well as the process by which sediments are shed into the slope environment.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)