Abundance and size changes in the calcareous nannofossil Schizosphaerella - Relation to sea-level, the carbonate factory and palaeoenvironmental change from the Sinemurian to earliest Toarcian of the Paris Basin

The contribution of Schizosphaerella carbonate (CaCO3schizo) to the total carbonate (bulk CaCO3) in the Paris Basin was minor (< 6%) and short-term fluctuations of both parameters show no correlation. However, the CaCO3schizo and bulk CaCO3 show similarities in their long-term trends, suggesting a possible relationship between the biotic carbonate production and the export of allochthonous carbonate to the Paris Basin.