Oligocene-Miocene age of aridity in the Atacama Desert revealed by exposure dating of erosion-sensitive landforms

The age of onset of hyperaridity in the Atacama Desert, Chile, which is needed to validate geological and climatological concepts, has been heretofore uncertain. Measurement of cosmogenic 21Ne in clasts from erosion-sensitive sediment surfaces in northern Chile shows that these surfaces have been ba...

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Bibliographic Details
Published in:Geology (Boulder) 2005-04, Vol.33 (4), p.321-324
Main Authors: Dunai, Tibor J, González López, Gabriel A, Juez-Larré, Joaquim
Format: Article
Language:English
Subjects:
arid environment
Atacama Desert
Cenozoic
Chile
Climate change
Desertification
deserts
eolian features
erosion
exposure age
geochronology
hyperarid environment
isotopes
landforms
Miocene
Ne-21
Neogene
neon
noble gases
northern Chile
Oligocene
paleoclimatology
Paleogene
sediments
Soil erosion
South America
stable isotopes
Stratigraphy
terrestrial environment
Tertiary
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Summary:The age of onset of hyperaridity in the Atacama Desert, Chile, which is needed to validate geological and climatological concepts, has been heretofore uncertain. Measurement of cosmogenic 21Ne in clasts from erosion-sensitive sediment surfaces in northern Chile shows that these surfaces have been barely affected by erosion since 25 Ma. Surface exposure ages of sediment clasts give replicate values at 25, 20, and 14 Ma and individual values at 37 and 9 Ma. Predominantly hyperarid conditions are required to preserve these oldest continuously exposed surfaces on Earth. Our findings are compatible with the hypothesis that the onset of aridity in the Atacama Desert could be the reason for, rather than the consequence of, uplift of the high Andes.
ISSN:0091-7613
1943-2682
DOI:10.1130/G21184.1