Ostreidos de la Unidad de Sopuerta (límite Aptiense inferior/ superior; Cuenca Vasco Cantábrica): estudio geoquímico y diagenético

Abstract

The realization of geochemical and diagenetical studies on fossil oyster’s shells from the «Calizas Nodulosas con Ostreidos y Limolitas de Sopuerta unit» has allowed demonstrating the variations in the luminescence of different microstructures, mainly in the Regular Foliated one (RF), as a result of different burial depths. The structural properties of the distinguished microstructures made possible, to a greater or lesser extent, the circulation of diagenetic fluids which provided the shell with diagenetic elements like Fe, Mn or Mg. As a result of this cationic exchange, the shell enriched the fluids with Na or Sr, considered primitive elements in oyster’s shells. The importance of the rocky matrix in the geochemical alterations has been demonstrated, comparing the results of this study with the results obtained by Higuera-Ruiz and Elorza (2006)