Pliocene-Quaternary tectonic-sedimentary evolution of the NE Alboran Sea (SW Mediterranean Sea)

Abstract

The Pliocene-Quaternary tectonic-sedimentary evolution of the NE Alboran Sea is established using high-resolution seismic profiles. The Pliocene-Quaternary deposits resting upon an acoustic basement with a complex morphostructure are stratigraphically made up of three seismic sequences whose facies, stratal patterns and nature of boundaries result from the interaction between sea-level changes, tectonics and physiographic configuration. During the Early Pliocene, a generalized synsedimentary transgression with extensive tectonic activity resulted in a homogeneous sedimentation deformed by extensional tectonic activity along two main fault systems (NE-SW and NW-SE). The sediment distribution was controlled by the pre-existing palaeotopography. During the Late Pliocene, a generalized synsedimentary regression with a N-S compressive tectonic activity favoured the development of a great variety of seismic facies related to the initiation of the Almeria turbidite system and the triggering of gravity mass-flow deposits. The deformation of these seismic facies was mainly controlled by the transcurrent NE-SW and NW-SE structures, and their distribution was related to the point source represented by the Almeria Canyon. During the Quaternary, the high-frequency sea-level oscillations coeval to NNW-SSE compressive tectonic activity resulted in the progradation of the margin, the occurrence of instability phenomena, and the sedimentary displacements of the Almeria turbidite system. An analysis of subsidence evolution shows an attenuation during the Pliocene-Quaternary, from a maximum of 342 m/m.y. to 160 m/m.y. for the total subsidence, and from a maximum of 196 to 116 m/m.y. for the tectonic subsidence.