Modificaciones diagenéticas en nodulos de sílex por influencia de fluidos dolomitizantes: ejemplos en el Cretácico superior de la Región Vasco-Cantábrica

Abstract

Special nodular chert detected in carbonates of the Upper Cretaceous in the Basque-Cantabrian Region was partially or completely modified by diagenesis. Rhombohedral dolomite crystals appear both within the carbonate host-rock and the interior of chert nodules. Unlike the common unaltered nodular chert from other sections or stratigraphic horizons, the dolomitized chert shows an enhancement of secondary porosity and suggests the Mg-rich fluids in alkaline environment were responsible for diagenetic modification