Understanding the atmospheric variability of the last glacial-interglacial transition in the Southern Hemisphere through paleoclimatic studies of high-altitude loess-paleosol sections in Argentina

TORRE, GABRIELA; GAIERO, DIEGO M; ROUX, GAEL LE; DE VLEESCHOUWER, FRANCOIS; COSENTINO, NICOLÁS; OLIVEIRA SAWAKUCHI, ANDRÉ

Roma

Congreso; XXI INQUA Congress "Time for change"; 2023

Internarional Union for Quaternary Research

Atmospheric aerosols can have a significant impact on the global climate system due to the changes in the solar energy balance and the thermal radiation they produce, and also by affecting the primary productivity of oceans associated with increased deposition of iron. The loess-paleosols sequences located in Argentina are the most extensive continental paleo-records of aeolian material in the Southern Hemisphere, recording the deposition of dust transported by two major zonal wind systems: the southern westerly winds and the subtropical jets. In order to increase the understanding of paleo-atmospheric circulation over the Southern Hemisphere during the late Pleistocene-early Holocene, we are planning to determine physical properties (grain-size distribution and magnetic susceptibility) of two loess-paleosols sequences located in elevated regions. These analyses will be followed by optically stimulated luminescence (OSL) dates and provenance studies through radiogenic isotopes. In this sense, we will increase the existing spatial coverage of high-resolution paleoclimatic studies of loess sequences in southern South America, by adding to our previous studies two fairly unexplored sections: one located in the mountainous regions of NW Argentina (2100 m a.s.l.) and another in the Plateau of the Pampean Ranges (1600 m a.s.l). We hypothesize that these loess-paleosols records located in elevated regions, record the deposition of dust transported exclusively by the high-altitude circulation of the subtropical jet streams and grain-size variations of the deposits will evidence changes in the wind intensity. Therefore, these new sections will provide valuable complementary information for the Pampean loess belt about past variability in wind belts´ position/intensity. Also, these studies will improve our understanding of the influence of the dust sources located in the Puna-Altiplano Plateau, and the latitudinal movement of the subtropical jet stream circulation over the past climatic hemispheric variability. Ongoing results will be discussed in the conference session.