Implicaciones tectosedimentarias de la discontinuidad estratigráfica del Maastrichtiense medio en Aspe (Prebético de Alicante)

Abstract

A major sedimentary unconformity, middle Maastrichtian in age, has been recognized in the uppermost Cretaceous, hemipelagic deposits outcropping near Aspe (SE Spain, Prebetic Domain). The exceptional outcropping conditions allow detailed sedimentological and biostratigraphical analyses of the unconformity and its tectosedimentary interpretation. This unconformity implies submarine erosion and a later onlap, and represents an important change in the sedimentary conditions. The unconformity separates two completely different units: the lower unit (the uppermost part being latest Campanian-early Maastrichtian in age) is built by rhythmic hemipelagic carbonate sequences deposited in a calm open marine environment; the upper unit (late Maastrichtian in age) is basically formed by marls and marly limestones with evidences of synsedimentary instability during the sedimentation. The unconformity is interpreted as the result of a tectonic compressive event pointed by the development of synsedimentary reverse faults (and related paleorelieves), turbiditic layers, slumps and olistholiths. Correlation of this unconformity with other Prebetic areas allows to integrate its tectosedimentary implications within the geodynamic evolution of the Betic Ranges, during the beginning of the Alpine convergence.