ABSTRACT: Gulf of Mexico Foraminiferal Size Data and Its Incorporation Into A Paleoecologic Zonafion Using The Paleoecologic Expert System (PALEX)

RAGAN, JERRY M., RICHARD C. BECKER, and TOM D. LEE

Foraminiferal size data are presented from over 400 bottom samples from the Gulf of Mexico. Of the 74 common species investigated, 25 exhibit an increase in maximum size with increasing water depth. Qualitative terms such as small and large are assigned numerical values, corresponding to bathymetric zones. Quantifying size increases the number of key paleoecologic indicators available for interpretation. This is especially helpful for zonations based on species' upper depth limits.

These key indicators were combined with our existing paleoecologic understanding to formulate consistent paleoecologic rules. These rules form the foundation of the Paleoecologic Expert System (PALEX), a PC based program. PALEX applies these expert rules to well data to rapidly produce a consistent paleoecologic interpretation. Interpretations can be displayed on a sample by sample basis, or averaged using a predetermined filter. Distribution of the key paleoecologic indicators within each sample can be plotted, and confidence levels assigned to the interpretation.

Plotted alongside fossil abundance/diversity curves and normalized distribution of key ecologic species, these interpretations can help identify sedimentary cycles within regional sequences. Integrating these data with electric log and seismic data permit more detailed correlation of sands. A local high-resolution biostratigraphic zonation from the Cooper Field, Garden Banks 386/387 is presented.

AAPG Search and Discovery Article #90941©1997 GCAGS 47th Annual Meeting, New Orleans, Louisiana