A Study of Geochemical and Microbial Processes in Hydrate-Bearing Sediments Associated with Seep Environments in the Gulf of Mexico  

Sandip Bordoloi, Department of Geological Sciences, University of Alabama, Tuscaloosa, AL 35401, [email protected]

Northern Gulf of Mexico seafloor is characterized by extrusion of oil and gas from deep reservoirs into surface sediments. These anoxic seep sites in the middle of nutrient poor deep waters of the Gulf of Mexico (GOM) support a variety of life forms including chemosynthetic communities on the surface and microbial communities within the sediments. Studying extant geological products of microbial processes helps one understand extinct microbial processes operating in a particular environment when direct evidences of these processes like fossilized microbes are not available. In this study I have classified observed seeps as “warm” (~42⁰C) and “cold” (~7⁰C) seeps based on the calculated (oxygen isotope thermometry) and recorded pore fluid temperatures. My main objective is to compare and contrast various bio-geochemical signatures recorded in the sediments of these seep sites. It will be of interest to document the effect of temperature on the microbial processes and authigenic precipitates within the sediment. Pore fluid profiles are available from twin cores in Gulf of Mexico. Information about partitioning of major (CaO, MgO, Fe₂O₃, SiO₂, Al₂O₃, K₂O, P₂O₅, TiO₂, MnO) and minor (Ba, Sr) elements between pore fluids and geologic products will be obtained from the collected data. Moreover, this study will help classify seep environments (e.g. “warm” or “cold”) in the geological record based on the bio-geochemical signatures developed in this study.