Sedimentological studies of contourite deposits in the northern Argentine Continental Margin

ROBERTO A. VIOLANTE; GRAZIELLA BOZZANO; SUSANA MARCOLINI; CECILIA LAPRIDA; MARÍA JULIA ORGEIRA; ADRIANA BLASI; NATALIA GARCÍA CHAPORI; JOSÉ LUIS CAVALLOTTO; DANIELA SPOLTORE

Hull

Workshop; International Workshop University of Hull; 2013

The Argentine Continental Margin contains a very extensive Contourite Depositional System (CDS), one of the largest worldwide (Hernández Molina et al., 2008, 2009). Following these pioneering papers, other contributions were related to different regional aspects of the CDS (Gruetzner et al., 2012; Hernández Molina et al., 2012 a; Muñoz et al., 2012, Violante et al., 2012 a, b). The northern sector of the CDS, adjacent to eastern Buenos Aires Province (Argentina) and Uruguay, has been studied in detail during recent years after carrying out several geophysical (seismic and bathymetric), geological and oceanographic cruises on board the Research Vessels “Meteor” (Germany) and “Puerto Deseado” (Argentina). The performed studies focused on different perspectives such as seismic stratigraphy, morpho-sedimentary processes and dynamics, sea floor-water masses interaction, sedimentary facies and regional evolution (Violante et al., 2010; Bozzano et al., 2011; Henkel et al., 2011, Krastel et al., 2011; Hernández Molina et al., 2012 b; Preu et al., 2012 a, b). During the Argentine geological cruises LBIV (2009) and LBV (2012) in the continental slope off eastern Buenos Aires Province (37º30’-41ºS, off Mar del Plata and Bahia Blanca areas), 16 piston cores were retrieved from the contouritic features that constitute the terraces of the slope. Further, a new geological cruise (LBVI) is planned for 2013 off Bahia Blanca area with the objective of obtaining additional cores. Results arising from the sedimentological study of some of the cores obtained in 2009 in a sector of the Ewing Terrace (T2) close to the head of the Mar del Plata Submarine Canyon around 38ºS (Bozzano et al., 2011, Marcolini et al., 2012), depicted three contouritic facies (sandy-silty, gravelly and muddy) plus one hemipelagic facies. The contouritic facies are composed of dominant terrigenous, volcanic-pyroclastic mineralogical associations sourced in the Andean, extra-Andean Patagonian and Pampean regions. Presently ongoing activities are aimed at studying, on the entire slope off eastern Buenos Aires Province, the sedimentary and physical properties of the contouritic deposits, performing detailed grain size and sedimentological parameters analyses, magnetic susceptibility and mineralogy, as well as micropaleontological content. The objective is to better characterize the contouritic facies and to establish genetic and evolutive relationships, with special emphasis on the sedimentary processes, the role played by dominant water masses, the influence of climatic changes and the interaction between along-slope and down-slope processes.