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Carbon Isotope Chemostratigraphy as a Regional Correlation Tool in Subsurface Mississippian Strata of the Anadarko Basin, Oklahoma-Kansas, USA


The Mississippian section of the U.S. Midcontinent-Anadarko Basin has been a prolific hydrocarbon reservoir since the 1920s, yet regional subsurface stratigraphic correlation remains difficult due to complexities in facies distributions, diagenetic overprinting, and poor biostratigraphic constraints. Changes in the global carbon cycle during the Mississippian imparted large fluctuations in the dC value of the oceans, which are preserved as systematic stratigraphic shifts in dC values through Mississippian carbonate successions world-wide. The nature and timing of the isotopic shifts are well-understood and can be correlated to the Global Boundary Stratotype Section and Point (GSSP) for the Mid-Carboniferous boundary in Arrow Canyon, NV. To evaluate the potential of Mississippian carbon isotope chemostratigraphy as a correlation tool in the Anadarko Basin, carbon and oxygen isotopic compositions were determined on 321 closely spaced samples through the Albert Severin well (API: 35047007110000) in Garfield County, OK, USA. The dC values range from −2.5 to +3.5‰ VPDB, with most values falling between +1 and +3‰. The d18O values show much greater variability, ranging from −7.5 to −1.5‰. The resulting trend of large decreases in d18O accompanied by relatively small decreases in dC values is characteristic of limestones affected by burial diagenesis and indicates good preservation of primary dC values. When plotted versus depth, dC values reveal stratigraphic variation that is not only facies-independent, but also consistent with the carbon isotope chemostratigraphy of the GSSP. As such, results indicate that the Albert Severin Core contains a nearly continuous section of the lowermost Kinderhookian through Lower Chesterian, and highlight the potential of carbon isotope chemostratigraphy as a robust regional correlation tool for spatially complex Mississippian strata of the Anadarko Basin.