Estudio petrográfico y geoquímico de los principales niveles de lutitas negras del Cretácico de Asturias

The Cretaceous deposits of Asturias are traditionally considered the host rock for the oil offshore. Selected Cretaceous b/ack shale levels of Asturjas (Northern Spain) are studied with the aim to check their oil generation potential. Most of the black shales (Albian-Cenomanian) were formed in a mud plain where vegetal debris were transported and accumulated. They have very low oil generation potential. Occasionally, detritic amber levels were formed. They exhfuit high pyrolysis yields. Only in Llames de Parres a very rich oil shale was found. lt was generated in a restricted marginal setting with high organic productivity and is mostly made up of algal lacustrine material. The maturity leve/ was low in ali the study places and no regional trend was detected.