THE AEOLIAN DUST DEFLATED FROM SOUTHERN SOUTH AMERICA AND ITS RELATIONSHIP WITH PALEORECORDS OF THE SOUTHERN HEMISPHERE.

GILI, S.; D. M. GAIERO; CHEMALE, F.; KOESTNER K.; SL GOLDSTEIN

Congreso; XIX INQUA; 2015

During the last few decades, dust has become an important component in paleoclimatic studies as it is employed as a proxyof wind systems characteristics and changes in the atmospheric circulation patterns. For Southern South America (SSA), themajor present-day dust source areas are located in a continuous N-S band of arid and semi-arid terrains extending from thecoastal regions of Peru to Patagonia. Three main persistent source areas stand out: three present-day dust sources have beenidentified: Patagonia (39-52◦S), central-western Argentina (CWA, 26-33◦S), and Puna-Altiplano plateau (PAP, 19-26◦S). Inorder to characterize the most important potential dust sources in SSA, 54 surface sediment (SS) samples were collected fromthe first 5 cm of arid and semi-arid terrains that span ̃4000 km from the southern Altiplano to the southern tip of South America ̃54◦S). We present new isotopic (i.e., Sr, Nd and Pb) data for SS defining the geochemical fingerprint of the entire arid diagonalof SSA. These data are then compared with similar data obtained for different paleoclimatic records (e.g., Antarctic ice coresand Southern Ocean marine sediments). Recent studies suggest that PAP and Patagonia have been important suppliers of theaeolian material found in Antarctic ice and Southern Ocean marine sediments. Supporting this, our preliminary results indicatethat, in fact, SSA would be the most important source of dust deposited in these paleo-records during glacial-interglacial times.Furthermore, we evaluate the grain-size dependence of Sr, Nd and Pb isotopes by contrasting the results using two different sizefractions; a finer sediment fraction (