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This content will become publicly available on April 25, 2019

Title: A late Quaternary paleoenvironmental record in sand dunes of the northern Atacama Desert, Chile

This study reports a previously unidentified paleoenvironmental record found in sand dunes of the Atacama Desert, Chile. Long-term aeolian deflation by prevailing onshore winds has resulted in the deposition of sand on the irregular surface of a Miocene-aged anhydrite outcrop. Two deposits ~25 km apart, along the prevailing wind trajectory, were hand excavated then analyzed for vertical (and temporal) changes in physical and chemical composition. Radiocarbon ages of organic matter embedded within the deposits show that rapid accumulation of sediment began at the last glacial maximum and slowed considerably after the Pacific Ocean attained its present post-glacial level. Over this time period, grain sizes are seen to increase while accumulation rates simultaneously decrease, suggesting greater wind speeds and/or a change or decrease in sediment supply. Changes in δ 34S values of sulfate in the sediment beginning ~10 ka indicate an increase in marine sources. Similarly, δ 2H values from palmitic acid show a steady increase at ~10 ka, likely resulting from aridification of the region during the Holocene. Finally, due to the extreme aridity in the region, these sand dunes retain a well-preserved chemical record that reflects changes in elevation and coastal proximity after the last glacial maximum.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [4]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Environmental Science, Policy and Management; Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Center for Accelerator Mass Spectrometry
  2. Univ. of California, Berkeley, CA (United States). Dept. of Environmental Science, Policy and Management; Univ. of Chile, La Pintana (Chile). Dept. of Engineering and Soils. Faculty of Agricultural Sciences
  3. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
  4. Univ. of California, Berkeley, CA (United States). Dept. of Environmental Science, Policy and Management
Publication Date:
Report Number(s):
LLNL-JRNL-717742
Journal ID: ISSN 0033-5894; 861607
Grant/Contract Number:
AC52-07NA27344; DEB-1406956; 0819972
Type:
Accepted Manuscript
Journal Name:
Quaternary Research
Additional Journal Information:
Journal Volume: 90; Journal Issue: 1; Journal ID: ISSN 0033-5894
Publisher:
University of Washington - Cambridge University Press
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of California, Berkeley, CA (United States); California Inst. of Technology (CalTech), Pasadena, CA (United States); Univ. of Chile, La Pintana (Chile)
Sponsoring Org:
USDOE; National Aeronautic and Space Administration (NASA); National Science Foundation (NSF); National Commission for Scientific and Technological Research (CONICYT) (Chile)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; hyperarid Atacama Desert; sand dune; paleoenvironment; isotope analyses; biological soil crust (BSC); lichen; fog
OSTI Identifier:
1461747