New insights about the Upper Jurassic - Lower Cretaceous sedimentary successions from Asturias (NW Iberian Peninsula)

© 2014, Universidad Complutense de Madrid. All rights reserved. Detailed mapping of the Jurassic to pre-Albian deposits of central and eastern Asturias (NW of the Iberian Peninsula) allowed several Upper Jurassic and Lower Cretaceous outcrops, previously assigned to other ages, to be identified. Where possible, these outcrops were correlated with the well-known sequences outcropping on the Asturian coast. A new Jurassic stratigraphic unit, the Miyares Formation, was defined, consisting of a conglomerate Lower Unit, a Middle Unit composed mainly of oolitic limestones and an Upper Unit comprising bioclastic and marly limestones with a rich larger foraminiferal fauna. The Lower Unit is interpreted as deposited in a fan delta, the Middle Unit represents a shallow marine high-energy environment, and the Upper Unit deposited on a restricted shallow marine platform. The shallow-water foraminiferal assemblage from the Upper Unit is attributed to the Tithonian and the oldest Cretaceous rocks are Barremian. Therefore, there is a stratigraphic gap recorded in the study area, which might correspond to the latest Jurassic to Early Cretaceous pro parte timespan.