87Sr/86Sr ratios in inoceramids (Bivalvia) and carbonate matrix as indicators of differential diagenesis during burial. Early Maastrichtian Bay of Biscay sections (Spain and France). Potential use for chemostratigraphy?

To determine, for chronostratigraphic purposes, whether the Maastrichtian seawater 87 Sr/ 86 Sr ratio has been preserved in calcite shells, oxygen, carbon, and strontium isotope analyses have been carried out on carbonate matrix and inoceramid shell samples from deep-sea carbonate sediments at the Sopelana and Bidart sections in the Basque-Cantabrian Basin. These analyses were compared with clay-mineral distributions from the same locations. In...