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

Ciudad de Buenos Aires

Conferencia; International Conference & Exhibition (ICE); 2018

AAPG

In the framework of thePAMPA AZUL Project, a program launched by the Argentinean Government to deepeninto the scientific knowledge of the Argentinean Sea for its conservation andprotection, the Marine Geology Working Group (GTGM) performed, between 2017 and2018, three oceanographic cruises (YTEC-GTGM-0, GTGM-1 and GTGM-2) on board theArgentinean R/V Austral. Three sectors of the Argentine Continental Margin(ACM) - Tierra del Fuego, West Malvinas and Patagonia - have been surveyed withthe Kongsberg swath bathymetry echo sounders EM 122 and EM2040 as well as witha Teledyne ATLAS PARASOUND P70 sub-bottom profiler. In addition, 33 gravitycores have been obtained in these areas in water depths that vary from 130 m to3480 m, thus encompassing from the shelf break to the lower slope. The finalobjective of the GTGM is to undertake a multidisciplinary investigation of theevolution of the ACM during the Late Quaternary where sedimentary processes,tectonic control, source-to-sink and paleoceanographic reconstructions will beintegrated. The present contribution focuses on the sedimentologicalinformation gathered by the preliminary study of the sediment cores that,together with the bathymetry and seismic profiles, will allow us to identifythe principal morpho-sedimentary features in the three study areas. This is anespecially attractive task as the ACM is characterized by a complex ContouriteDeposition System (CDS), originally described by Hernandez-Molina et al.(2009), that interact with 5 Submarine Canyon Systems, formerly illustrated byLonardi and Ewing (1971). In the Tierra del Fuego area (~55º S), the mostoutstanding feature is the Sloggett (Sverdrup) Canyon that incises thecontinental shelf and reaches 3800 m water depth. Here, downslope sedimentaryprocesses and tectonic lineaments probably controlled the canyon inception(Palma et al., 2018). However, sediment cores from the middle sector of thecanyon contain thick hemipelagic sequences, suitable for detailedpaleoceanographic reconstructions. In the West Malvinas sector (~54º S),along-slope processes seem to dominate with alternation of sandy and muddycontouritic facies. In the Patagonian sector (~43-47º S), the northwardsflowing Antarctic water masses interfere with the Patagonia Submarine CanyonSystem giving rise to a complex set of mixed contouritic-turbiditic facies, inmost cases overlain by foram-rich hemipelagic facies.