Major modification of sediment routing by a large Mass Transport Deposit in the Gulf of Lions (Western Mediterranean)

• Published in: Marine geology 2019-05, Vol.411, p.1-20
• Main Authors: Dennielou, Bernard, Jegou, I., Droz, Laurence, Jouet, Gwenael, Cattaneo, Antonio, Berné, Serge, Aslanian, Daniel, Loubrieu, Benoit, Rabineau, Marina, Bermell, Sylvain
• Format: Article
• Language: English
• Subjects: Sciences of the Universe
• ISSN: 0025-3227
• DOI: 10.1016/j.margeo.2019.01.011

In the Gulf of Lions (Western Mediterranean), the emplacement of a large (160 km3) Mass Transport Deposit, the Rhone Western Mass Transport Deposit (RWMTD), at the base of slope, aside the Rhone deep-sea fan between 1800 and 2700 m water depth, resulted in a major modification of the sediment routing by clogging a drainage network and blocking at the base of slope sediments that were previously routed into the Valencia channel and the Balearic abyssal plain. The RWMTD was sourced from sediments of the western flank of the Rhone upper fan and the adjacent base of slope. The mass transport deposit is characterized by a transparent seismic facies and sediment cores show that it is composed of a stiff laminated muddy lithofacies characteristic of the Rhone fan turbidites with marked contorted beds indicative of remoulding. AMS radiocarbon dating shows that the RWMTD was emplaced between 19.9 and 21.5 ka cal BP. It is coeval, within dating uncertainties, with the emplacement of a megaturbidite in the Balearic Abyssal Plain and immediately predates a major avulsion of the Rhone turbidite channel that led to the emplacement of an avulsion lobe (the neofan) on top of the RWMTD. It is not possible to affirm a genetic link between these three major gravity events but one can argue that they share a common forcing in relation with massive turbiditic accumulation during the last sea-level lowstand at the end of the Last Glacial Maximum. This study outlines the importance of mass transport deposits in the building of turbidite systems and, more generally, the major control of mass wasting on the routing and dispersal of sediments across continental margins.