Modificaciones diagenéticas en la microestructura de los inocerámidos (Bivalvia) de la Formación de Plentzia (Santóniense, Arco Vasco)

Abstract

noceramid shells, from the Santonian of the Basque Arc, have been tested to determine the preservation of their original prismatic microstructure formed by low magnesium calcite (LMC). Petrography and cathodoluminescence (CL) show, although they have good aspect, shells underwent a clear burial diagenesis. They suffered replacement by fibrous silica; strong compaction with pressure solution; and a final stage of cementation. Under CL the prisms show yellow to red luminescence with an evident cationic modification, and in addition, it allows to see the advance of the diagenetic fluids through prismatic boundaries, and to establish the chronology of the diagenetic processes, which altered selectively their original microstructure and composition