Paleoenvironmental changes in southern South American dust sources recorded by clay minerals of the Pampean loess

MATIAS ROMERO; GABRIELA TORRE; DIEGO GAIERO

Buenos Aires

Simposio; Blowing South; 2021

Instituto Franco-Argentino sobre Estudios de Clima y sus Impactos

Clay minerals are among the most ubiquitous minerals on earth’s surface. Different climatic conditions produce different clay minerals that can be recorded in the geologic archive providing insights into past weathering scenarios. However, in southern South America, scarce information is available from clay mineral assemblages found in aeolian sediments, such as loess deposits. Moreover, there is a lack of studies employing clay minerals for paleoclimatic reconstruction at dust sources and loess deposits. Therefore, we explore the clay mineral composition of modern dust source areas in southern South America and within the pampean loess to gain insight into paleoenvironmental conditions prevailing during the late Pleistocene- early Holocene in the region. We find that clay minerals recovered from the loess deposits are of an allochthonous origin, implying their formation at the ‘arid diagonal’, then blown away, and deposited downwind in the Pampas without post-depositional changes, hence shedding light on the weathering conditions at the dust sources during the last glacial/interglacial transition.