Seismic evidence for Messinian detrital deposits at the western Sardinia margin, northwestern Mediterranean

International audienceBased on new (‘SESAME 01' cruise) and previous seismic reflection data, this paper evidences the effects of the Messinian Salinity Crisis on the sedimentation at the western Sardinian margin. In the lower part of the margin, Messinian detrital deposits are organized into two successive, 300 m thick units. According to their shape, facies and extent, they are similar to alluvial fans, presumably fed by subaerial erosion of the upper margin. Whereas the earliest body is observed continuously all along the margin and the adjacent part of the deep basin, the youngest one is restricted to the vicinity of the canyons. This pattern could therefore sign a late Messinian sea-level rise, as suggested by detrital fan conglomerates sampled in a similar position along the northern Ligurian margin. We observe salt-related deformation of the Messinian detrital units, and the top of the salt layer gradually turn into a detrital delta seaward, implying that at the deep margin, most of the salt deposited before the low-stand Messinian delta emplaced, probably during the main Messinian sea-level drop or at the beginning of the low-stand sea-level