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Compositions of modern dust and surface sediments in the Desert Southwest, United States

Journal of Geophysical Research F: Earth Surface

By:
, , , and
DOI: 10.1029/2008JF001009

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Abstract

Modern dusts across southwestern United States deserts are compositionally similar to dust-rich Av soil horizons (depths of 0-0.5 cm and 1-4 cm at 35 sites) for common crustal elements but distinctly different for some trace elements. Chemical compositions and magnetic properties of the soil samples are similar among sites relative to dust sources, geographic areas, and lithologic substrates. Exceptions are Li, U, and W, enriched in Owens Valley, California, and Mg and Sr, enriched in soils formed on calcareous fan gravel in southeast Nevada. The Av horizons are dominated by dust and reflect limited mixing with substrate sediments. Modern dust samples are also similar across the region, except that Owens Valley dusts are higher in Mg, Ba, and Li and dusts both there and at sites to the north on volcanic substrates are higher in Sb and W. Thus, dust and Av horizons consist of contributions from many different sources that are well mixed before deposition. Modern dusts contain significantly greater amounts of As, Cd, Cr, Cu, Ni, Pb, and Sb than do Av horizons, which record dust additions over hundreds to thousands of years. These results suggest that modern dust compositions are influenced by anthropogenic sources and emissions from Owens (dry) Lake after its artificial desiccation in 1926. Both modern dusts and Av horizons are enriched in As, Ba, Cu, Li, Sb, Th, U, and W relative to average crustal composition, which we interpret to indicate that the geologic sources of dust in the southwestern United States are geochemically distinctive.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Compositions of modern dust and surface sediments in the Desert Southwest, United States
Series title:
Journal of Geophysical Research F: Earth Surface
DOI:
10.1029/2008JF001009
Volume
114
Issue:
F1
Year Published:
2009
Language:
English
Publisher:
AGU
Publisher location:
Washington, D.C.
Description:
F01028
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research F: Earth Surface