Late Quaternary paleoenvironments and paleoclimatic conditions in the distal Andean piedmont, southern Mendoza, Argentina

TRIPALDI, A.; ZÁRATE, M.A.; BROOK, G.; GUO-QIANG LI

QUATERNARY RESEARCH

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Ámsterdam,; Año: 2011 vol. 76 p. 253 - 263

0033-5894

The Andean piedmont of Mendoza is a semiarid region covered by very extensive and partially vegetated dune fields consisting of mostly inactive aeolian landforms of diverse size and morphology. This paper is focused on the San Rafael plain (SRP) environment, situated in the distal Andean piedmont of Mendoza (34º 30´S), and reports the sedimentology and OSL chronology of two representative exposures of late Quaternary deposits discussing their paleoenvironmental and paleoclimatic significance. Eleven facies, including channel, floodplain, fluvio-aeolian interaction, reworked pyroclastic and aeolian deposits, were described and grouped into two facies associations (FA1 and FA2). FA1 was formed by unconfined sheet flows, minor channellized streams and fluvial-aeolian interaction processes. FA2 was interpreted as aeolian dune and sand sheet deposits. OSL chronology from the SRP sedimentary record indicates that between ca. 58-39 ka and ca. 36-24 ka, during MIS 3, aggradation was governed by ephemeral fluvial processes (FA1), under generally semiarid conditions. During MIS 2, the last glacial maximum (ca. 24-12 ka), a major climatic shift to much more arid conditions is documented by significant aeolian activity (FA2) that became the dominant sedimentation process north of the Diamante-Atuel fluvial system. The inferred paleoenvironmental conditions from the SRP sections are in broad agreement with regional evidence.