Cenomanian through basal Coniacian Calcareous Nannofossil biostratigraphy of theMancos Shale reference section, Mesa Verde National Park, CO

A key discovery in the biostratigraphy of Mesa Verde's Mancos Shale reveals that the Cenomanian-Turonian boundary is bracketed by Tethyan nannofossil zone CC10b, occurring between 22.7–27.6 meters. This finding aligns with prior stage boundary placements and supports the existence of an unconformity in the basal Smoky Hill Member, further refined through lithostratigraphic correlations. The study also introduces Lithraphitdites eccentricum Watkins as a potential upper Cenomanian marker and proposes Eprolithus octopetalus Varol as a lower Turonian indicator, offering new datum points for stratigraphic analysis. The research integrates calcareous nannofossil biostratigraphy with macrofossil data and bulk-rock carbonate 13C values to provide precise temporal frameworks for the Upper Cenomanian through basal Coniacian intervals.

Corbett, M. J., & Watkins, D. K. (2014). Cenomanian through basal Coniacian Calcareous Nannofossil biostratigraphy of theMancos Shale reference section, Mesa Verde National Park, CO. Stratigraphy, 11(1), 97–108. https://doi.org/10.29041/strat.11.1.05