ABSTRACT

A new foraminiferal biozonation for the Neogene through Pleistocene bathyal strata of the Gulf of Mexico/Gulf Coast Basin (onshore and offshore) is introduced. This deep-water zonation is composed of fifty foraminiferal events, including nine each in the Pleistocene and Pliocene, eleven in the Upper Miocene, twelve in the Middle and nine in the Lower Miocene. These horizons include world-wide (LAD) and Gulf of Mexico wide extinctions (GOM LAD), local events, acmes and reoccurring events. The majority of these datums are limited to the bathyal zone (200-2000 m/600-6000 feet paleowater depths), although several range into the outer neritic (outer shelf) paleoenvironment.

This bathyal zonation, primarily using benthic species, includes both published and previously unpublished markers. Zonation applications are enhanced correlation between established planktic markers, greater correlation potential in deep expanded sections, and high correlative potential between Gulf Coast Basin bathyal sediments and other basins. This zonation may provide an approximate method for relating other deep-water Neogene through Pleistocene strata to the Gulf of Mexico Basin by using benthic index fossils which produce a narrower resolution than planktic markers alone.

Environmental conditions of the bathyal realm and methods for establishing the zonal scheme are discussed. The geographic utility of foraminiferal horizons, both within and beyond the Gulf Coast Basin (if applicable), is considered. The utility of selected shelf markers in the bathyal zone and the multiple reoccurrences of agglutinated (arenaceous) foraminiferal facies are addressed. The proposed zonation is based on extensive well studies from recently active exploration in deep-water sediments (offshore and onshore Louisiana and Texas) of the Gulf of Mexico (GOM) Basin. This zonation should enhance correlation between shelf and bathyal sediments as well as between exclusively bathyal sections in the Gulf of Mexico/Gulf Coast Basin.