Plio–Quaternary prograding clinoform wedges of the western Gulf of Lion continental margin (NW Mediterranean) after the Messinian Salinity Crisis

Abstract

In contrast to the much-studied onshore and deep offshore post-Messinian sedimentary history of the Gulf of Lion, the continental shelf had been poorly explored until recently. New seismic data, acquired by ELF Oil Company on the Languedoc–Roussillon shelf (Western Mediterranean Sea), from Cap Creus in the SW to Cap d’Agde in the NE, together with data from previously drilled exploratory wells, allow us to propose a scenario for margin reconstruction following the Messinian Salinity Crisis. The seismic data display a complex pattern of prograding clinoforms and buried submarine canyons. Following the crisis that eroded the previous margin, clinoforms developed as the new Pliocene margin prograded. Three major periods characterize the evolution of the post-Messinian margin. During the first period, after the filling of the Early Pliocene rias which are now above sea level, the prograding sedimentary prisms rapidly migrated seaward and filled the underlying Messinian topographic lows. The second period consists of a transitional interval, which began with a pronounced fall in sea level that probably corresponded with the end of the Lower Pliocene. Deposits were disturbed by large slumped structures. The third period is characterized by the appearance and development of submarine canyons near the subsequent shelf edges, maybe as a result of the increased glaciations and related sea-level changes. From that time onward, most of the Late Pliocene and Quaternary sediments were directly transferred down to the deep basin.