Temporal and paleoenvironmental reconstruction of the Claron Formation in Bryce Canyon National Park through calcite U–Pb geochronology and continental trace fossil characterization

Bryce Canyon National Park (BRCA) on the Paunsaugunt Plateau in Southern Utah is internationally known for its striking hoodoos that form from the Claron Formation. Despite this notoriety, the geologic history of the Claron Formation is enigmatic. This formation is described as a carbonate lacustrine–alluvial system that persisted throughout the Paleocene to Eocene Epochs (~66 to 34 Ma). Unlike other well studied formations such as the Green River Formation, a detailed understanding of the chronology, regional tectonic context, and timing of Paleogene lake development and paleoenvironments of the Claron formation remains poorly constrained. This study combines uranium-lead carbonate age dating, field mapping and thin section analysis of various lithofacies within the pink and white members of the formation, along with an examination of continental trace fossils to reconstruct the processes and paleoenvironments that make up the Claron. Analysis indicates a complex and dynamic ephemeral lake system with an abundance of unique and diverse continental trace fossils. These trace fossils include possible examples of Eatonichnus, Celliforma, Parawonichnus, and other traces, which have traditionally been interpreted as dung beetle burrows, bee and wasp cocoons, and ant nests, respectively. Preliminary fieldwork and laboratory results include, detailed new field mapping and CT scanning of unique trace fossils, U–Pb (calcite) LA-ICPMS age dating results from pedogenic and lacustrine carbonates, and thin section characterization, provide important new information on the Claron Formation that will help to decipher this diagenetically complex carbonate system. This initial data will also permit correlation of BRCA and the Paunsaugunt Plateau with better studied records in the Green River Formation, Uinta Basin, Bighorn Basin, and other well-known locations to fill in the larger geologic past of the Western United States.