Recent mass transport deposits in the Gulf of Cagliari

Sedimentary deposits due to slope failures and submarine landslides are common on continental margins. The availability of five new high resolution 2D multi-channel seismic profiles, integrated by Multibeam data, provides unprecedented insight into the shallow submarine geomorphology of the Gulf of Cagliari. The study area, located in the southern Sardinia offshore, exhibits several Mass Transport Deposits (MTDs) during the Upper Quaternary. They move from the continental slope and the north-east flank of the Banghittu High. We identified the recent 26 km long MTD-CG1, of which we interpreted the translational domain, characterized by weak deformation, and the toe domain, with a predominantly compressional and erosional regime. This erosion is produced locally by the basal shear zone (bsz) which represents the detachment surface of the slide. Both MTD domains are crossed by vertical conduits and fluid migration that produce buried pockmarks. In the translational domain an underlying carbonate buildup offered greater strength to sliding, resulting in an undisturbed sector. The MTD-CG1 is composed of Middle-Upper Pleistocene sediments which, during the Holocene, assumed an initial direction towards SE, to become towards the SW in the Carbonara Valley. After the gliding, the MTD was cut by the last incision phase of the canyon system which markedly characterizes the physiography of the gulf. The MTD-CG1 is primarily predisposed to instability by its steep slope gradient and fluid presence, while possible triggers include eustatic sea level changes and seismic activity.