A simple model accounting for the uptake, transport, and deposition of wind-eroded mineral particles in the hyperarid coastal Atacama Desert of northern ChileReportar como inadecuado




A simple model accounting for the uptake, transport, and deposition of wind-eroded mineral particles in the hyperarid coastal Atacama Desert of northern Chile - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Resumen

As previously observed in marine sediments collected downwind of African or South American continental sources,recent studies of sediment cores collected at the bottom of Mejillones Bay in north Chile 23°S show a laminated structure inwhich the amount of particles of aeolian origin and their size create significant differences between the layers. This suggestsinter-annual to inter-decadal variations in the strength of the local southerly winds responsible for 1 the erosion of the adjacenthyperarid surface of the Mejillones Pampa, and 2 the subsequent transport of the eroded particles towards the bay. A simplemodel accounting for the vertical uptake, transport, and deposition of the particles initially set into motion by wind at the surfaceof the pampa is proposed. This model, which could be adapted to other locations, assumes that the initial rate of vertical uptakeis proportional to the horizontal saltation flux quantified by means of White’s equation, that particles are lifted to a height H,increasing with the magnitude of turbulence, and that sedimentation progressively removes the coarsest particles from the aircolumn as it moves towards the bay. In this model, the proportionality constant A linking the vertical flux of particles with thehorizontal flux, and the injection height H control the magnitude and size distribution of the deposition flux in the bay. Theirvalues are determined using the wind speed measured over the pampa and the size distribution of particles collected in sedimenttraps deployed in the bay as constraints. After calibration, the model is used to assess the sensitivity of the deposition flux to thewind intensity variations. The possibility of performing such quantitative studies is necessary for interpreting precisely thevariability of the aeolian material in the sediment cores collected at the bottom of Mejillones Bay.



Autor: Alfaro, Stephane; - Flores Aqueveque, Valentina; - Foret, Gilles; - Caquineau, Sandrine; - Vargas Easton, Víctor; - Rutllant Cos

Fuente: http://repositorio.uchile.cl/



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