Minimum LGM Dust Deposition on the South American Loess and its Possible Relationship with a Coeval Maximum in Antarctica

COPPO, R.; COSENTINO, N. J.; TORRE, G.; DEL RIO, I.; OLIVEIRA SAWAKUCHI, A.; KOESTER, EDINEI; BERMAN, ANA LAURA; GAIERO, D. M.

Simposio; Blowing South: Southern Hemisphere Dust Symposium; 2021

IFAECI, Núcleo Mileno Paleoclima, AACS, CR2, UNLPam, INCITAP, CICTERRA, CESIMAR, GEOTRACES, ipam

We present a regional study of the Pampean loess in South America based on a detailed analysis of threesections across the core of the Pampas. High-resolution luminescence dating resulted in a new chronologythat covers a period from Marine Isotope Stage 3 to the early Holocene. Reliable estimations of massaccumulation rates (MARs) for loess were used to infer the temporal dust flux variation during the lastglacial/interglacial transition in southern South America (SSA). Minimum MARs in each section wereidentified for the Last Glacial Maximum (LGM), contrasting with high dust fluxes observed in more distalSouthern Atlantic Ocean (SAO) and East Antarctica. We hypothesize that the power of the Pampean loess asa sink of dust was reduced during the LGM, allowing long-range transport of SSA dust to SAO and EastAntarctica. This hypothesis is consistent with proxy data and models suggesting drier conditions in thePampas during the LGM, which would have shut down loess accumulation. It is also consistent with isotopicevidence that points to northern Patagonia and southern central-western Argentina as main contributors ofdust to East Antarctica during glacials, given that the prevailing regional wind system implies that dustemitted from these regions would have necessarily passed through the Pampas in its way to the SAO andEast Antarctica. Forthcoming Nd, Sr, and Pb isotope results for the Pampean loess will allow further testingof this hypothesis.