Dolomitización bajo superficies de ruptura sedimentaria: estudio comparativo de las dolomías del Turoniense-Coniaciense (El Ribero) y Maastrichtiense superior (Quecedo) del Norte de Burgos (España)

Abstract

Substantial dolomitization and calcitization processes occurred in upper Turonian-lower Coniacian and upper Maastrichtian-lower Danian carbonates at El Ribero and Quecedo sections, respectively. Carbonate precipitation is in both cases related to first order sequence boundaries. Textures under S.E.M. reveal m o re im p o rta n t processes o f dissolution at El Ribero in comparison to those a t Quecedo, suggesting an aggressive meteoric phreatic zone. C and O isotopic relations tend to become positive just below the unconformities as a result of the influence of marine waters. A general comparison show more heavy isotopic values at Quecedo. A marine/mixing water model of dolomitization is proposed for both dolomites, but with a major influence of marine waters at Quecedo