A morphosedimentary characterization of three areas of the Argentine Continental Margin

ISOLA, J; TASSONE, A; PALMA, F; BOZZANO, G; ORMAZABAL, J; SPOLTORE, D

Roma

Conferencia; 34th IAS Meeting of sedimentology; 2019

international Association of Sedimentologists

In the framework of the PAMPA AZUL Project, a program launched by the Argentinean Government to deepen into the scientic knowledge of the Argentinean Sea for its conservation and protection, the Marine Geology Working Group (GTGM) performed, between 2017 and 2018, three oceanographic cruises (YTEC-GTGM-0, GTGM-1 and GTGM-2) on board the Argentinean R/V Austral. Three sectors of the Argentine Continental Margin (ACM) - Tierra del Fuego, West Malvinas and Patagonia - have been surveyed with the Kongsberg swath bathymetry echo sounders EM 122 and EM2040 as well as with a Teledyne ATLAS PARASOUND P70 sub-bottom proler. In addition, 33 gravity cores have been obtained in these areas in water depths that vary from 130 m to 3480 m, thus encompassing from the shelf break to the lower slope. The nal objective of the GTGM is to undertake a multidisciplinary investigation of the evolution of the ACM during the Late Quaternary where sedimentary processes, tectonic control, source-to-sink and paleoceanographic reconstructions will be integrated. The present contribution focuses on the sedimentological information gathered by the preliminary study of the sediment cores that, together with the bathymetry and seismic proles, will allow us to identify the principal morpho-sedimentary features in the three study areas. This is an especially attractive task as the ACM is characterized by a complex Contourite Deposition System (CDS), originally described by Hernandez-Molina et al. (2009), that interact with 5 Submarine Canyon Systems, formerly illustrated by Lonardi and Ewing (1971). In the Tierra del Fuego area (~55º S), the most outstanding feature is the Sloggett (Sverdrup) Canyon that incises the continental shelf and reaches 3800 m water depth. Here, downslope sedimentary processes and tectonic lineaments probably controlled the canyon inception (Palma et al., 2018). However, sediment cores from the middle sector of the canyon contain thick hemipelagic sequences, suitable for detailed paleoceanographic reconstructions. In the West Malvinas sector (~54º S), along-slope processes seem to dominate with alternation of sandy and muddy contouritic facies. In the Patagonian sector (~43-47º S), the northwards owing Antarctic water masses interfere with the Patagonia Submarine Canyon System giving rise to a complex set of mixed contouritic-turbiditic facies, in most cases overlain by foram-rich hemipelagic facies.