INVESTIGADORES
TRIPALDI Alfonsina
congresos y reuniones científicas
Título:
Paleoenvironmental evolution of a subtropical inland paleo-dune field of western Pampas, Argentina during the past ~50 ka
Autor/es:
TRIPALDI, A.; FORMAN, S.L.
Lugar:
Tunuyan
Reunión:
Conferencia; IV Southern Desert Conference; 2014
Institución organizadora:
Laboratorio de Paleo-Ecologia Humana, Universidad Nacional de Cuyo
Resumen:
Presently
stabilized eolian deposits are common across the subtropical region of
Argentina, with paleo-dune fields in the Andean piedmont and the
central-western Pampas (?Pampean Sand Sea?), passing into loess and loessoids
in the eastern and northern Pampas, related principally to late Miocene uplift
of the Andes and enhanced glaciations during the late Quaternary. In the San
Luis paleo?dune field, western Pampas, there was episodic accumulation of
eolian sand during the last ~50 ka. Sedimentological and
pedological analysis of 16 stratigraphic sections allowed distinguishing, at
least, four eolian units bounded by buried soils and/or erosive surfaces that
were chronologically constrained by OSL dating of +50 quartz extracts. These units, following previous denominations, are here included in the
El Chulengo Alloformation, comprising the Allomembers: Nahuel Mapá (N.M.)
deposited at ~51?33 ka, Sayapé (S.) at ~27?17 ka, Estancia Los Pocitos (E.L.P.)
at ~12?1 ka and Los Crispines (L.C.) during the last 200 yr. These deposits
represent different episodes of eolian aggradation of the San Luis paleo?dune
field, separated by periods of landscape stability and likely less arid
conditions. The eolian units can be correlated to distinctive landscape
elements. NNW?SSE linear ridges and southeasterly megaparabolic paleodunes
tentative correspond to the oldest N.M. Allom. and northeasterly megaparabolic
paleodunes to the late Pleistocene S. Allom. The Holocene sedimentation
produced an extensive eolian sand sheet and, tentatively, sinuous ridges (E.L.P.
Allom.) and the youngest eolian episode (L.C. Allom.) reactivated the landscape
forming barchanoid ridges within the megaparabolic paleodunes and new blowouts.