Incremento lateral hacia el Oeste del grado diagenètico en el Maastrichtiense medio del Arco Vasco: evidencias en inocerámidos y roca encajante

Abstract

Inoceramid bivalve shells and host-rock samples from the mid-Maastrichtian carbonate rocks have been collected at Sopelana, Zumaya, San Sebastián, Loyaand Bidart sections (So-Zu-Ss-Lo-Bi), corresponding to the Basque Arc Domain. The main purpose was to determinate the progressive post-depositional changes suffered by the shells together with the marl and marly-limestone beds. Petrography, scanning electron microscope (SEM) and cathodoluminiscence (CL) observations, as well as oxygen and carbon isotopic values show that calcite prisms, which form the shell microstructure, have undergone a more intense diagenetic modification in the western (Sopelana section) than in the eastern areas (Bidart section) of the Basque Arc, without any substantial textural changes in the prismatic microstructure