The Rosario section in northeastern Mexico and its potential as a reference section for the Turonian-Coniacian boundary

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The Turonian/Coniacian (T/C) boundary is undefined today, although several sections have been considered regarding their potential as a GSSP (Global Boundary Stratotype Section and Point). The Rosario quarry site in northwest Coahuila, Mexico, comprises a 53 m thick sedimentary succession of limestone and marl. The sedimentary succession seems lithostratigraphically continuous and monotonous without major condensation or hiati. Sediments were deposited in a distal marine environment hundreds of kilometres from the nearest shore line and are rich in age-diagnostic invertebrates (e.g. inoceramids, ammonites). However, when trying to correlate the existing biozonation and the delta13C curve with other sections, challenges appear in detail. Important questions need to be solved regarding the completeness and precision of the inoceramid record, particularly in the critical boundary interval. From the current point of view, the Rosario section is among the most expanded Turonian-Coniacian boundary sections worldwide and a potential GSSP candidate for the T/C boundary. We here ask for the opportunity to re-log and re-sample the El Rosario quarry section in order to carry out high-resolution biostratigraphical and geochemical analyses, for the refinement of long-distance correlation (e.g. to Europe). Biostratigraphy will be supported and refined by stable isotope stratigraphy with proper resolution, and the events will be age-calibrated by Sr isotopy. We will like that evaluate the potential of the Rosario section as GSSP for the Turonian/Coniacian boundary.