Inocerâmidos y belemnites del Cretâcico Superior en facies de la creta (Aquitania, Pays de Caux, NE Ardenas): diferente comportamiento frente a la diagénesis

Abstract

Upper Cretaceous inoceramid bivalves and belemnite rostra from three sections (Aquitaine, Pays de Caux and NE Ardennes) are petrologically and geochemically analysed. The coarse prismatic calcite of the inoceramid shells has undergone diagenetic alteration without substantial textural changes in the original microstructure. Inoceramid oxygen isotope ratios together with a generalised bright red-yellowish cathodoluminescence colour indicate that this type of shells have been more affected by diagenesis than belemnite rostra. Belemnite calcitic rostra better retain the primary environmental isotopic signal and turn out to be the most promising organisms as regards the study of palaeoenvironmental conditions in this facies