A morphosedimentary characterization of three areas of the Argentine Continental Margin

PALMA F.I.; J.P. ORMAZABAL; ISOLA J.; BOZZANO G; SPOLTORE D; A. TASSONE

Roma

Encuentro; 34th International Meeting of Sedimentology (IAS).; 2018

Universidad de Roma

The southernArgentine Continental Margin (ACM) is incised by deep and large canyons thatbelong to the canyon?s system of Tierra del Fuego. The Sloggett Canyon, locatedin northwestern Scotia Sea, is the longest with a total length of 142 km alongthe thalweg, cutting the continental shelf, slope and abyssal plain. In thiswork we present a morphosedimentary and structural analysis of the canyonrevealed from recently data obtained on board the R/V Austral in the YTEC-GTGM0cruise in September 2017. It consists in the first complete very-high resolutionimaging (up to 20 meters) of the canyon from its upper part down to itsdistalmost reach. Swath bathymetry with the echosounder EM-122 and sub-bottomprofiler with Parasound P70 were used for distinguish morphologies made byprocesses of erosion, transport and deposition. The head is affected bytributaries channels that range in size, direction and depth and act as aconduit for gravity flows and turbidity currents. They have a wide expressionin the east flank regarding the western flank where predominate wall slumping,gullies and scar. The canyon was studied considering three parts of thethalweg, where the direction changes abruptly two times from NW-SE to SW-NE inan angle of approximately 90 degrees. This was associated with the NW-SElineaments of the West Scotia Ridge, where could be acted as a path for thecanyon and the Beagle Channel Fault System that has a W-E direction affectingthe slope. Additionally, along-processes related to the strong oceanic currentsform contourites drifts and erode the margin to form contourites terraces alongcanyon depth. The canyon has a connection with the Sloggett Bay (10 km north)and can be considered as a continuation of the Sloggett Continental TectonicLineament. Keywords:Canyon, geomorphology, multibeam bathymetry, sub-bottom profiler, Scotia Sea