El Ciclo Valanginiense superior-Hauteriviense inferior en la Sierra de Seguraregistro de una etapa de extensión cortical en el Cretácico Inferior de la Zona Prebetica

Abstract

In the western Prebetic (Sierra de Segura, Betic Cordillera) the upper Valaginian-lower Hauterivian deposits mark the beginnig of the Cretaceous sedimentation in this region of Southern Iberia. This event occurred after the death of the uppermost Jurassic shallow platforms, in the lower Valanginian. The stratigraphic succession studied corresponds to a sedimentary cycle which includes two shallowing-upwards depositional sequences limited by supra-regional unconformities. Marine sediments predominate during the UpperValanginian, these being deposited on a mixed homoclinal ramp. Lower Hauterivian onlapping sediments were deposited in a platform dominated by bioconstructions of corals and stromaporids, with abundant carbonate mud. The study of stratigraphic architecture lead to the conclusion that sedimentation was coetaneous to a crustal extension phase. The equivalent evolution found in other sections of Iberia supports that this synsedimentary tectonics was associated with the opening o f the Nothern Atlantic. As a consequence, along the Southern Iberian paleomargin, a synrift stage in transtensional regime occurred between the Upper Jurassic and the upper Aptian.