PRELIMINARY GEOCHEMICAL TAPHONOMY OF BONE BED SITES IN THE YELLOW CAT MEMBER OF THE CEDAR MOUNTAIN FORMATION, UTAH

Several significant bone bed sites have been discovered in early Cretaceous terrestrial sediments from the basal Yellow Cat Member of the Cedar Mountain Formation on the eastern side of the San Rafael Swell, Utah. These sites include the Crystal Geyser Dinosaur Quarry, Dalton Wells Dinosaur Quarry, Doelling's Bowl, Don's Ridge Sites, and the Suarez Site and are believed to contain the oldest Cretaceous terrestrial faunal record in the United States.

Taphonomic investigations have begun on several of these sites including rare earth element (REE) taphonomy. REE's are being used to determine the geochemistry of the fossilization environment and evaluate the degree of taphonomic reworking. A particular emphasis of this study is to identify variability in fossilization environments and assist in identification of multiple accumulation events within seemingly uniform bone deposits.

The presence of spring derived carbonate nodules, tuffas, and mounds coupled with significant positive cerium anomalies, and high spatial variability of rare earth elements in bones, indicate that ancient springs contributed to the preservation and geochemistry of bones in the Crystal Geyser and Doelling's Bowl areas. In contrast Dalton Wells lack spring derived carbonates and suggest that high sedimentation rates were more important to bone preservation.