PLIOCENE-QUATERNARY TECTONIC-SEDIMENTARY EVOLUTION OF THE NE ALBORAN SEA (SW MEDITERRANEAN SEA)

The Pliocene-Quaternary tectonic-sedimentary evolution of the NE Albor an Sea is established using high-resolution seismic profiles. The Plio cene-Quaternary deposits resting upon an acoustic basement with a comp lex morphostructure are stratigraphically made up of three seismic seq uences whose facies, stratal patterns and nature of boundaries result from the interaction between sea-level changes, tectonics and physiogr aphic configuration. During the Early Pliocene, a generalized synsedim entary transgression with extensive tectonic activity resulted in a ho mogeneous sedimentation deformed by extensional tectonic activity alon g two main fault systems (NE-SW and NW-SE). The sediment distribution was controlled by the pre-existing palaeotopography. During the Late P liocene, a generalized synsedimentary regression with a N-S compressiv e tectonic activity favoured the development of a great variety of sei smic facies related to the initiation of the Almeria turbidite system and the triggering of gravity mass-flow deposits. The deformation of t hese seismic facies was mainly controlled by the transcurrent NE-SW an d NW-SE structures, and their distribution was related to the point so urce represented by the Almeria Canyon. During the Quaternary, the hig h-frequency sea-level oscillations coeval to NNW-SSE compressive tecto nic activity resulted in the progradation of the margin, the occurrenc e of instability phenomena, and the sedimentary displacements of the A lmeria 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 t o 116 m/m.y. for the tectonic subsidence.