--> --> Geochemical Evaluation of the Mississippian Limestone, Anadarko Shelf, Oklahoma

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Geochemical Evaluation of the Mississippian Limestone, Anadarko Shelf, Oklahoma

Abstract

A thorough geochemical evaluation of the Mississippian Limestone interval in the Anadarko shelf which combines stable isotope geochemistry, trace and rare earth element geochemistry and biomarker geochemistry is lacking. The on-going study aims to fill this knowledge gap by investigating environmental conditions at time of deposition of this hydrocarbon-bearing interval utilizing a set of drill core. The multi-proxy approach employed in the current study allows robust evaluation of depositional water column redox conditions, detrital input to the water column and organic matter origin and fate. Preliminary results from analysis of bulk stable nitrogen isotopes and concentrations of trace element proxies of redox suggest that water column and benthic depositional redox conditions were oxic to suboxic. Rock-Eval analysis of samples suggests that the analyzed samples contain autochthonous, marine organic matter with characteristic biomarkers that are distinguishable from those of the regionally extensive Woodford Shale. On-going work is focused on further evaluation and characterization of Mississippian Limestone-derived biomarkers in order to refine organic matter type and consequently, to determine organic matter provenance. Concentrations of rare earth elements within the section being studied is also being pursued so as to ascertain detrital input into the water column during deposition and to determine connectivity of the study site to the open ocean during the Mississippian.