BREARD, SYLVESTER Q., ARDEN D. CALLENDER, and MICHAEL J. NAULT, Paleo Control Inc., Houston, TX

ABSTRACT: Paleoecologic and Biostratigraphic Models for Pleistocene Through Miocene Foraminiferal Assemblages of the Gulf Coast Basin

We have developed operationally oriented paleoecologic models used in hydrocarbon exploration of the Gulf Coast basin for Pleistocene through Miocene foraminifera and an updated, refined biostratigraphic chart. We also present estimated paleoecologic tolerances for major benthic and planktic foraminiferal markers, and discuss a number of rules and problems encountered in oil industry paleoenvironmental reconstruction.

Key benthic paleoenvironmental markers for particular depth zones are graphically presented for the Pleistocene through Miocene. Improvements over previous models include greater use of calcareous and arenaceous foraminiferal species not used or recognized in earlier studies.

Finer subdivisions of bathyal paleoenvironments are of particular significance due to current Gulf of Mexico deep-water exploration. Operationally, the abyssal environmental is difficult to recognize due to a reliance on faunal abundance to delineate abyssal from bathyal and the lack of abyssal zone markers.

A number of genera and species are identified as having changed habitat preference through time. Some forms have moved progressively into deeper water (Ceratobulimina Cyclammina cancellata and Nonion pompiloides). Conversely, the movement of species into progressively shallower occurrences through time (Pullenia bulloides) appears to be less common.

The widespread occurrence of known Gulf of Mexico foraminiferal species from countries such as Mexico, Venezuela, Ecuador, Jamaica, Trinidad, and the Dominican Republic, suggests that these models have direct application to Neogene studies in Central America, South America, the Caribbean, and the U.S. Gulf Coast.

We introduce a variety of deep-water benthic marker foraminifera, many for the first time. These taxa help fill gaps for deeper-water sections where standard benthic marker foraminifera do not occur, helping debunk the popular myth that benthic foraminifera are useless as markers in the exploration of deep-water sections.

AAPG Search and Discovery Article #90989©1993 GCAGS and Gulf Coast SEPM 43rd Annual Meeting, Shreveport, Louisiana, October 20-22, 1993.