The stratigraphic record of the Late Jurassic-Early Cretaceous rifting in the Alto Tajo-Serranía de Cuenca region (Iberian Ranges, Spain)Genetic and structural evidences for a revision and a new lithostratigraphic proposal

Abstract

The Southwestern Iberian Domain (Southiberian Basin) corresponds to one of the five palaeogeographic domains into which the Iberian Basin was divided during the Late Jurassic-Early Cretaceous rifting stage. Although it was already known that this domain was clearly separated into two sub-basins, Cuenca and Valencia, the same lithostratigraphic scheme was assumed to be applicable to the whole domain. In the last decades, new data have been incorporated to the knowledge of the Serranía de Cuenca and the Alto Tajo region, showing that this area underwent a separated palaeogeographic evolution and developed a different stratigraphic record. Evidences of such independence are, among others, the development of a Late Jurassicearly Barremian unconformity with unique features in the Iberian Basin and herein described for the first time. Syn-rift sedimentation was controlled by an intricate extensional geometrical and kinematic pattern of multiple and small half-graben basins, and it is represented by just two unconformity-bounded units, late Barremian and Aptian in age respectively. This work reviews, clarifies, and simplifies old and confusing stratigraphic nomenclatures and proposes a specific lithostratigraphic scheme for the Alto Tajo-Serranía de Cuenca region. It includes the new upper Barremian Tragacete Formation and the redefinition of La Huérguina Formation in terms of lithofacies, lower boundary, age and environmental interpretation.