Late Glacial–Holocene climatic transition record at the Argentinian Andean piedmont between 33 and 34° S

A E Mehl,M A Zárate

doi:10.5194/cp-10-863-2014

Abstract

Abstract. The Arroyo La Estacada (~ 33°28' S, 69°02' W), eastern Andean piedmont of Argentina, cuts through an extensive piedmont aggradational unit composed of a dominant Late Pleistocene–early Holocene (LP–EH) alluvial sequence that includes several paleosols. One of these paleosols developed affecting the topmost part of likely Late Glacial aeolian deposits aggraded into a floodplain environment by the end of the Late Pleistocene. The paleosol shows variable grade of development along the arroyo outcrops. Organic matter humification, carbonate accumulation and redox processes were the dominant processes associated with paleosol formation. By the early Holocene, when the formation of the paleosol ended, renewed alluvial aggradation and high magnitude flooding events affected the arroyo's floodplain environment. Accordignly, a period of relative landscape stability in the Arroyo La Estacada basin is inferred from the paleosol developed by the LP–EH transition in response to the climatic conditions in the Andes cordillera piedmont after the Late Glacial arid conditions. The analyzed Late Glacial–Holocene alluvial record of the Andean piedmont constitutes a suitable record of the LP–EH climatic transition in the extra-Andean region of Argentina. It is in agreement with regional paleoclimatic evidence along the southern tip of the South American continent, where other pedosedimentary sequences record similar late Quaternary paleoenvironmental changes over both fluvial and interfluvial areas.

Highlights

The understanding of earth’s past climatic evolution is considered the key to get a better understanding of the presentday climatic system and the development of long-term climatic change forecasts (Saltzman, 2002)
This work contributes to the knowledge of the dominant paleoenvironmental and paleoclimatic conditions during the Late Glacial to early Holocene climatic transition in the eastern Andean piedmont between 33 and 34◦ S
Paleosol features developed in close relation to the climatic conditions dominating the setting of the South American Arid Diagonal at Late Glacial and early Holocene transition

Summary

Introduction

The understanding of earth’s past climatic evolution is considered the key to get a better understanding of the presentday climatic system and the development of long-term climatic change forecasts (Saltzman, 2002). At the southern tip of South America, the late Quaternary paleoclimatic conditions have been mainly revealed by the glacial fluctuations in the Andes cordillera (Clapperton, 1993; Espizua, 1993, 1998, 1999; Coronato and Rabassa, 2007; Rabassa, 2008). The study of buried paleosols has been concentrated in the loess sequences that dominate the Pampean region, where the largest loess plain of South America has developed with a nearly 50 m thick loess record (Fig. 1a). The eastern region of the Pampean plain has been a classic area to analyze Quaternary Argentinean paleosols (Teruggi and Imbellone, 1987; Imbellone and Teruggi, 1993; Blasi et al, 2001; Zárate et al, 2002; Kemp et al, 2004b; Imbellone and Cumba, 2003, among others). Some studies were conducted in the loess–paleosol sequence of northwestern Argentina with the aim of inferring

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