Ostracode Biomarkers in the Paleogene of the Gulf of Mexico

Donald S. Van Nieuwenhuise
LDepartment of Geosciences, University of Houston, Houston, Texas 77204-5007

Biostratigraphic markers are essential for determining the isochroneity of seismic reflectors and similar log signatures in adjacent wells. It is important to be able to delimit a reservoir unit identified in one well from similar units in other wells that may or may not be genetically separated by time, sealing shales, or flooding surfaces. In the past, benthic foraminifera have been used as the primary biomarkers in transitional depositional settings in Gulf of Mexico exploration. Although ostracodes are often more abundant and sometimes more diverse in such settings, there are only two ostracodes species, Haplocytheridea stenzeli and Cytheridea sabinensis , among the standard biomarkers used in the Gulf Coast Paleogene. In the Atlantic and Gulf coastal plains, there are more than 100 useful ostracode biomarkers over this interval, and these important stratigraphic markers have not been widely used.

A scaled-solution biostratigraphic and magnetostratigraphic model for the Paleogene has been developed which calibrates many North American ostracode taxa to planktic foraminifer, calcareous nannoplankton, and dinocyst datums and zonations, and to the sequence of magnetic reversals. Generic ranges, new ostracode zones, and the defining biomarkers are presented herein. Due to significant taxonomic revisions, individual biomarkers within these ostracode zones are being studied further and published elsewhere. As these studies progress, they are being integrated into the scale-solution model. The increased number of biomarkers being integrated within global time scales allows the level of resolution required to identify reservoir units and their confining flooding surfaces.

 

AAPG Search and Discover Article #90069©2007 GCAGS 57th Annual Convention, Corpus Christi, Texas