2014 Rocky Mountain Section AAPG Annual Meeting

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Detailed Chemostratigraphic Characterization of the Niobrara Formation, Cemex Quarry, Lyons CO


The Cemex Lyons Quarry located 4 km northeast of Lyons, CO targets the Fort Hays Limestone of the Late Cretaceous Niobrara Formation on the western flank of the Denver-Julesburg Basin. In 2011, 24 exploration cores were drilled in a 60-acre field area north of the quarry to determine the extent of the Fort Hays Limestone. Cores from the 24 wells contain a nearly complete section of the Smoky Hill Member of the Niobrara Formation, the Fort Hays Limestone, and the uppermost section of the Codell Sandstone. With the recent advent of the portable XRF machine, chemostratigraphic characterizations have gained popularity in the Niobrara Formation of the Denver Basin. However, no study has been performed on such a small area with a high density of cores. This study will thus use XRF analyses, thin section petrography, and SRA to characterize the chemostratigraphy of the Niobrara Formation north of the Cemex quarry, relating trace element data to TOC values. Initial research suggests that small-scale heterogeneities in depositional styles, trace element distribution, and lateral bentonite continuity can be observed between cores only 150 m apart. Further research will attempt to geochemically fingerprint bentonite beds to discover further details about the paleoenvironment and provide a basin-wide correlation technique.