Edad de los términos basales del Cretácico Superior de la Depresión Intermedia (Pirineos occidentales, Nafarroa)

Abstract

The age of Upper Cretaceous basal sediments of the Central Depression (Western Pyrenees) has been considered to range from Cenomanian to Santonian according to previous authors. Newly studied samples show 3 planktonic foraminifera associations corresponding to M. schneegansi Zone, D. concavata Zone and D. asymetrica Zone. Thus, the base of the Upper Cretaceous is diachronous. This diachronism is attributed to the onlap of both previously formed palaeoreliefs (Upper Albian to Upper Turonian) and synsedimentary horst and graben created during the Upper Turonian-Coniacian lapse of time