EARLY CARBONIFEROUS STABLE ISOTOPE CHEMOSTRATIGRAPHY OF THE ST. JOE GROUP: CHEROKEE SLOPE, NORTHEASTERN OKLAHOMA, AND SOUTHERN MISSOURI

Carbon and Oxygen isotopes of bulk rock samples from four outcrops in the south-central United States will be used to create a regional chemostratigraphic correlation of the Early Mississippian-aged St. Joe Group. Evenly spaced samples throughout the formations in northeastern Oklahoma and southwestern Missouri will generate chemostratigraphic curves to identify depositional climate conditions, diagenetic alteration, regional correlation, and facies models. Stratigraphic contacts will be tested for isotopic evidence of subaerial exposure. The basal part of the St. Joe will be examined for evidence of the Bachelor Shale, which is absent in many Oklahoma exposures. Documentation of a depositional hiatus may indicate regional differences in sediment deposition and preservation. The isotopic data will be integrated with petrographic data to define facies successions of each outcrop. Local and regional facies variations will be used to identify depositional models, sedimentation rates, and location-based differences in diagenetic alteration. The isotopic data curves will be compared with the published international δ¹³C brachiopod curves to evaluate the utility of isotopic data as a lower Mississippian correlation tool. Anomalies will be acknowledged and variations will be discussed as regional climate, latitude, and syn-depositional alteration.