ABSTRACT

A set of Gulf of Mexico biostratigraphic and cycle charts has recently been completed for the Paleocene and Eocene; the Oligocene and Miocene; and the Pliocene and Pleistocene. The chart set includes: 1) onlap curves of second, third, and in some cases fourth-order cycles; 2) key flooding surfaces and sequence boundaries; 3) sequence stratigraphic and lithostratigraphic units; 4) important planktonic foraminiferal and nannofossil first and last appearance datums; 5) traditional benthic foraminiferal "tops" and recently compiled last appearance datums; 6) foraminiferal and calcareous nannofossil biochronozones; 7) industry biochronozones; 8) magneto- and stable isotope chronozones; and 9) selected industry stratigraphic codes e.g., Petroleum Information Corporation's Well History Control System (WHCS). While much of the information presented in this chart series is available from other published sources, some of the charted third and fourth-order sequences are newly defined and are based on the recent integration of numerous offshore and onshore subsurface studies in the Gulf of Mexico. For example, within the Discoaster prepentaradiatus third-order sequence, we have identified an additional third-order sequence. Following from this we have recognized that most sand- rich submarine fan deposition occurs within sequences deposited on second-order sea level falls. The inclusion of planktonic foraminiferal and calcareous nannofossil first appearance, i.e. "evolution point", datums in this chart series reflects the newly recognized utility of fossil "first evolutionary occurrences" as stratigraphic indices in wells with high resolution digital micropaleontological reports. Of particular importance are the first appearance datums (FADs) of: Globorotalia truncatulinoides (d'Orbigny), discernible in the great majority of Pliocene - Pleistocene wells; Orbulina spp., discernible in most Lower to Middle Miocene wells; and Hantkenina spp., occurring in many Lower to Middle Eocene wells.