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Composition of Aeolian Dust in Natural Traps on Isolated Surfaces of the Central Mojave Desert - Insights to Mixing, Sources, and Nutrient Inputs

Richard L. Reynolds, Marith Reheis, James Yount, Paul Lamothe

The recognition and characterization of aeolian dust in soil contribute to a better understanding of landscape and ecosystem dynamics of drylands. Results of this study show that recently deposited dust, sampled in isolated, mostly high-ground settings, is chemically and mineralogically similar on varied geologic substrates over a large area (15,000 km²) in the Mojave Desert. The silt-plus-clay fraction (fines) on these isolated surfaces is closely alike in magnetic-mineral composition, in contrast to greatly dissimilar magnetic compositions of rock surfaces of vastly different lithologies, on which the fines have accumulated. The fines, thus, are predominantly deposited dust. The amounts of potential nutrients in the sampled dust are much more uniform than might be provided by direct, local weathering of bedrock or by dust locally derived from nearby weathered products. The compositional similarity of the dust on these surfaces is interpreted to result from mixing of fines in the atmosphere as well as in fluvial, alluvial, and lacustrine depositional settings prior to dust emission.

Abstract of paper in press, 2006, Journal of Arid Environments

Photograph shows an example of a natural dust collector. The tan sediment is dust that has been trapped in an outcrop of limestone on top of a peak in the Mojave Desert. Spatula for scale.