CONICET | Buscador de Institutos y Recursos Humanos

The central region of Argentina, southern South America, is characterized by an extensiveQuaternary aeolian record. In this context, three locations from the southwestern Pampas, an Andeanforeland region bearing a rich fossil mammal record that contributed to the South Americabiostratigraphic scheme, were selected to carry out a comprehensive sedimentological analysis of thelate Quaternary deposits. The case studies are located at the Transverse Valleys of La Pampa province(Chapalcó, Quehué and Utracán-Argentino valleys), and exhibit a high resolution of the late Quaternary in comparison with others areas of the southwestern Pampas. The Toay locality (~36° 41′S, 64° 24′W)records aeolian-dominant activity since the end of the Late Pleistocene (~30 ka) onwards, soil formationat some point during the Holocene and early?mid 20th century reactivation of aeolian process. TheArroyo Quehué locality (~37°04? S, 64°42?W) presents a Late Pleistocene-Holocene succession mostlyrelated to an ephemeral endorheic fluvial system, with an interval of relative surface stabilization andaeolian aggradation during the Late Holocene. The Utracán locality (~37°17′S, 64°35′W) exhibits aprevailing aeolian and fluvial-aeolian interaction succession developed in the mid-to Late Holocene in asand-mud flat environment of a shallow saline lake. The three studied cases are representative ofaeolian aggradation in association with ephemeral fluvial, shallow lake and pedogenic processes in acurrently subhumid-dry region. Numerical ages indicate sedimentation during the last ~30 kyr. Theyallow constraining and evaluating the paleoenvironmental conditions in this inland region of southernSouth America, and provide age constraintsfor the regional databases of palaeoclimatic proxies. Theresults are in agreement with other late Quaternary paleoclimatic-paleoenvironmental archives ofcentral Argentina and show a fragile aeolian landscapethat is susceptible to deterioration under extremeconditions, including both aeolian reactivation during dry phases and erosion of sandy-silty sedimentsduring wet phases

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