Mid-Continent Section

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Early Mississippian St. Joe Group in northeastern Oklahoma to southwestern Missouri: Isotope chemostratigraphy


A regional chemostratigraphic correlation of the Early Mississippian St. Joe Group carbonates will be based on carbon and oxygen isotopes of bulk rock samples in the south-central US. Depositional climate conditions, diagenetic alteration, regional correlation, and facies modeling will be identified from evenly spaced samples throughout the formation at four outcrops in northeastern Oklahoma and southwestern Missouri. The paragenesis of the St. Joe Group will be determined using samples at formation contacts. Bulk rock δ13C curves will be compared to international δ13C brachiopod curves to correlate the time of deposition and the early Mississippian water climate. Regional differences in sediment deposition and preservation rates will be identified from differences in the preserved rock record at each site. Isotopic anomalies will be acknowledged and variations discussed as regional climate, latitude, and syn-depositional alteration. The underlying disconformable contact with the Devonian Woodford Shale will be tested to determine if time-equivalent rocks of the Bachelor Shale exist in the Oklahoma exposures. The isotopic data will be compared to thin section and hand sample analysis, allowing for a complete correlation of each outcrop and determination of diagenetic alteration. Further determination of diagenetic alteration and depositional environment will be examined using Mg, Mn, and Sr trace elements.