GEOCHEMICAL CHARACTERISTICS OF THE CASTLE ROCK CONGLOMERATE WITH IMPLICATIONS FOR PROVENANCE

The late Eocene Castle Rock Conglomerate (CRC) is one of the youngest preserved sedimentary rocks found in the Denver Basin. It is a thick, heterogeneous, arkosic conglomerate with large blocks of granite, quartzite, and Wall Mountain Tuff found in it (Evanoff, 2007). The latest Eocene age is based on its stratigraphic position as well as the existence of blue-grayish quartzite clasts and sourced from Coal Creek Canyon, roughly 75 km to the Northwest. This study attempts to determine the provenance of other clasts in the CRC, sampled in Castle Wood State Park, by analyzing the geochemistry of different clasts and comparing them to suspected bedrock sources elsewhere in the Colorado Rockies in an effort to develop a clearer understanding of the timing of post-Laramide erosional processes. Samples were collected from several locations within Castle Wood Canyon, and two suspected bedrock sources were sampled at Coal Creek Canyon and Staunton State. Geochemical analyses of bulk rock samples were performed by XRF analyses in order to identify potential bedrock sources, with final results to be determined. Provenance of CRC hypothesized to be transported from the Northwest of Castlewood Canyon.