Late Pleistocene and Holocene eolian deposits of the southern Pampas, Argentina

MARCELO ZÁRATE; ADRIANA BLASI

QUATERNARY INTERNATIONAL

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Rotterdam; Año: 1993 vol. 17 p. 15 - 20

1040-6182

The aim is to reconstruct the sedimentological history of the Late Pleistocene-Holocene eolian deposits of southem BuenosAires province. Hence, a preliminary model is proposed in order to analyze the different stages of the sedimentological cycle. The deposits include sandy loess, fine sand sheets and dunefields. The southern Buenos Aires province represents the depositional area, whereas the source and transport environments are located in the northern Patagonian Andes and northern extra-andean Patagonia. According to the mineralogical characteristics of the material, explosive volcanism is considered the predominant process of particle formation, particularly as generator of pyroclastic deposits which were reworked by different erosive processes (glacial, fluvial, eolian). During the Late Glacid Maximum and the Holocene, alluvial deposits which were mainly generated by fluvial erosion of volcaniclastic sedimentary units, were deposited along the floodplains of the Colorado and Negro rivers, including those distal segments located in the emerged offshore platform. The fluvial regime depended upon the regime of the glaciers, hence it reflected the major glacial fluctuations which took place in the Andes. Floodplains were deflated by southwest winds, transporting the material towards the southern Buenos Aires province (sandy loess and loessial sands) and to La Pampa province (dunefields).