Morphology of retrogressive failures in the Eastern Rhone Interfluve during the Last Glacial Maximum (Gulf of Lions, Western Mediterranean)

The Gulf of Lions (NW Mediterranean Sea) is a SW-NE oriented passive continental margin formed since the Oligocene. It presents small to large scale mass movement features suggesting a long history of seafloor instability. Of particular interest are the two surficial large mass-transport deposits along the Rhone turbiditic levee, known as the Rhone Eastern and Western Mass-Transport Deposits (REMTD and RWMTD). With the help of the recently acquired multi-beam bathymetric, sub-bottom profiler, high-resolution seismic and sedimentological data, we investigate the morphology, timing, kinematics, and possible triggering mechanisms of the source area of the REMTD, which we refer to as the Eastern Rhone Interfluve Slide (ERIS). ERIS has an estimated run-out distance of approximately 200 km. It covers an area of about 700 km2 and the volume of the mobilized material is approximately 110 km3. Our data reveal four individual glide planes within the ERIS complex which were most likely generated by retrogressive failures. The basal surfaces of the ERIS coincide with high-amplitude seismic reflectors similar to those previously interpreted as the expression of condensed sections on the upper slope. The turbiditic sequences sandwiched between the condensed sections likely control the localisation of potential weak layers favouring the failures. AMS radiocarbon dating yields an age of approximately 21 ka cal BP for the failures, which falls within the peak of the Last Glacial Maximum. The toe area of the ERIS is incised by several active listric faults rooted in the Messinian strata, which control the location of the slide scarps. The combination of several factors such as slope steepening, halokinesis, and excess pore pressure generation due to rapid turbiditic sedimentation during the Last Glacial Maximum are considered as the possible candidates for the triggering of the failures in the investigated slope.


Submarine landslide, Mass transport deposits, Gulf of Lions, Western Mediterranean, Turbiditic levees

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Badhani Shray, Cattaneo Antonio, Dennielou Bernard, Leroux Estelle, Colin Florent, Thomas Yannick, Jouet Gwenael, Rabineau Marina, Droz Laurence (2020). Morphology of retrogressive failures in the Eastern Rhone Interfluve during the Last Glacial Maximum (Gulf of Lions, Western Mediterranean). Geomorphology. 351. 106894 (19p.).,

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