HIGH-RESOLUTION STRATIGRAPHY OF THE PERMIAN CRADDOCK BONE BED, SEYMOUR, TEXAS

The Craddock Bone Bed, located on the Craddock Ranch (Seymour, Texas), is world-renowned for its well-preserved fossil Dimetrodon and other vertebrates. The bone bed is within the Permian (Kungarian-Artinskian) Clear Fork Formation of north Texas. Stratigraphic study of the Craddock Bone Bed has been ongoing, since it’s discovery. The deposit is interpreted as a mud-filled abandoned channel pond. A high-resolution stratigraphic study of the shale succession was completed to evaluate subtle changes in the deposit at the Kennesaw Quarry. Spectral gamma ray and magnetic susceptibility (MS) measurements were made at ten-centimeter intervals. Following acquisition of this geophysical data, physical samples were collected, from the same intervals, for further analysis. Physical samples of the shale were broken down to determine sand/mud content, sand mineralogy, and fossil content (micro and macro). Three primary positive MS excursions were observed correlating with Pedofacies 1 and Pedofacies 2 of the channel fill (Flis and Flis, 2024) and with the overlying deposition. Each positive anomaly decreases in magnitude from oldest to youngest. The lowest MS observed occurred coincident with a layer of fossil shark cartilage marking the death of the pond and the top of Pedofacies 2. Total gamma ray (API) measurements climb from the basal coarse deposits and remain consistent through the shale of Pedofacies 1 and Pedofacies 2. The overlying deposits see a decrease in gamma radiation. Thorium and potassium contributions follow this trend, with Thorium being the primary driver of the total gamma ray signature. Uranium contribution increases upward through the section. Pedofacies 1 and Pedofacies 2 are distinguishable in gamma ray data, but less obvious than in MS data. Trends in sand/mud content, sand mineralogy, and fossil content are discussed in relationship to the geophysical data and previous stratigraphic work at the Kennesaw Quarry.