New insights on sources contributing dust to the loess record of the western edge of the Pampean Plain during the transition from the late MIS 2 to the early Holocene

TORRE, GABRIELA; D. M. GAIERO; N. COSENTINO; R. COPPO; A. OLIVEIRA SAWAKUCHI

HOLOCENE (SEVENOAKS)

SAGE PUBLICATIONS LTD

Lugar: London; Año: 2019

0959-6836

High-resolution studies of paleo-records located closer to the dust source areas of South America are relevant for increasing the knowledge on past climatic conditions in the Southern Hemisphere. In this sense, the Pampean loess archives can offer explicit records of dust source/transport/deposition in the region, providing new insights which may be used to better understand the role of dust in future climate change scenarios. In this work, we study a loess sequence (Lozada site; ~31°39´S; 64°08´W) located at the foothill of the Eastern Pampean Range which represents the westernmost loess deposits within the so-called ?loess belt?. The studied sequence covers a span of time from the Late Deglaciation period up to the Early-Holocene. Loess samples from this record show two grain-size populations suggesting more than one dust source area. The dominance of a coarse silt subpopulation during the transition from MIS 2 to the Early-Holocene suggests that proximal dust sources were dominant at that time. Two of the most proximal dust sources were analyzed as the probable contributors to the Lozada site: sediments derived from the Eastern Pampean Ranges and sediments derived from the shorelines of the Mar Chiquita Lake. The geochemical data suggest that both areas were not significant dust sources to the eastern Pampean Plain during the studied interval. Instead, our chemical data suggest a dominant supply from a southern and relatively closer area, linked to the foothill of the Andes, and the increased activation during the Early Holocene of a more distant area contributing finer loess associated to a northern source located in the Puna region.