Las dolomías del Cretácico Superior del borde sur del Sistema Central: estudio preliminar

This study is focused on the carbonate units of the Late Cretaceous of the South margin of the Central System (Caballar: Castrojimeno and Burgo de Osma Formations). These units are totally or partially dolomitized, and they have been studied in order to interpret the timing and the diage- netic environment in which dolomites precipitated and to infer the mechanism for dolomitization. Petrographic and geochemical data of dolomites of the three units suggest that they precipitated from the same fluids despite the different sedimentary environments in which these units were deposited. Moreover, data suggest that dolomites precipitated via reflux of hypersaline brines proceeding from the overlying latest Cretaceous to Paleogene evaporitic units