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Visualizing the Microbiotic Response With Other Subsurface Data to Further Understand the Opening of the Gulf of Mexico and the Resulting Petroleum System

Abstract

A unique approach to visualizing a data-supported biostratigraphic review of twelve exploration boreholes located within the De Soto Canyon and Mississippi Canyon protraction areas in the northern Gulf of Mexico, intergrated with geophysical and petrophysical data, yields a repeatable and predictive evolutionary and paleoecological sequence with implications to paleogeography and petroleum systems. In the study area, the Jurassic is variable in stratigraphic thickness, suggesting that sea floor spreading remained active, possibly creating restricted and anoxic benthos. Foraminiferal, calcareous nannofossil, and palynofloral assemblages suggest stronger pelagic paleoenvironments, improved oxygenated benthos, and less terrestrial influence towards the end of the Jurassic. These observations combined with relatively high gamma ray response and geochemical proxies suggest and world-class late Tithonian source rock. The Jurassic/Cretaceous transition is nearly isopachous in the area, suggesting sea floor spreading ceased or slowed. This transition includes rich and diverse benthic assemblages, suggesting healthy oxygen circulation in the benthos; and an increased dominance of Nannoconus spp., suggesting increasing stratification in the surface waters. The post-Hauterivian section varies in thickness with the maximum thickness in Northern De Soto Canyon area and thinning to the south. Cycles between planktic and benthic fossil abundances probably indicate that progradation and eustacy became the dominant influence for deposition. Nannoconus continues to dominate the nannofossil assemblage through the Aptian when Watznauria spp. begins to comprise a higher percentage of the nannofossil assemblage, suggesting improved surface water circulation and/or seasonality during deposition.