Aeolian erosion and sand transport over the Mejillones Pampa in the coastal Atacama Desert of northern Chile
Aeolian erosion and sand transport over the Mejillones Pampa in the coastal Atacama Desert of northern Chile
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DOI：
10.1016/j.geomorph.2010.04.003
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发表时间：
2010-08
期刊：
影响因子：
3.9
通讯作者：
V. Flores‐Aqueveque;S. Alfaro;R. Muñoz;J. Rutllant;S. Caquineau;J. P. Roux;G. Vargas
中科院分区：
文献类型：
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作者：
V. Flores‐Aqueveque;S. Alfaro;R. Muñoz;J. Rutllant;S. Caquineau;J. P. Roux;G. Vargas
智利北方沿海阿塔卡马沙漠的梅吉约内斯半岛是一个海洋-大气-陆地相互作用特别强烈的地区，导致沿岸风增强，侵蚀表面并将沙粒输送到大海。由于梅希隆湾底部层状沉积物中的风成颗粒记录了盛行南风强度的长期变化，因此了解风蚀和泥沙搬运等风成过程对改善古海洋学重建至关重要。本研究的目的是通过实地测量来表征梅希隆半岛的北方部分的平坦地貌上的风蚀过程，包括风蚀对初始粒径分布的影响和移动颗粒的矿物组成的相关分馏过程。此外，我们测试的能力，现有的跃移模型（MB 95）再现的变化的侵蚀过程中的现场实验。在这个平坦的表面上，来自17个地点的土壤样本含有大量直径在200-300微米和100-150微米范围内的高度易蚀颗粒。收集在BSNE沙陷阱位于不同高度的表面附近的风成颗粒，表现出类似的土壤的可侵蚀部分的双峰尺寸分布;丰富的罚款类随高度增加。具有空间可变分布的小石头可以局部降低风蚀强度。运动颗粒的矿物组成与土壤相似，主要矿物为石英、长石和方解石，其次为粘土矿物、石膏和角闪石。计算每个土壤颗粒大小等级的u* 值。然后，利用白色（1979）公式计算各粒级对水平通量的基本贡献，最后通过积分得到总通量。跃移模型成功地再现了风蚀过程的变化，在现场实验，但高估了两个数量级的垂直积分质量通量现场测量。
The Mejillones Peninsula in the coastal Atacama Desert of northern Chile is a region in which ocean–atmosphere–land interactions are particularly strong, resulting in enhanced alongshore winds that erode the surface and transport sand particles to the sea. Because the aeolian particles in the laminated sediments at the bottom of Mejillones Bay record long-term changes in the intensity of prevailing southerly winds, it is fundamental to understand aeolian processes such as wind erosion and sand transport to improve paleoceanographic reconstructions. The aim of the present study is to characterize the wind erosion process over the flat geomorphology of the northern portion of the Mejillones Peninsula, the Mejillones Pampa, including the influence of wind erosion on the initial particle size distribution and the associated fractionation processes of the mineralogical composition of moving particles, through field measurements. In addition, we test the ability of an existing saltation model (MB95) to reproduce the variability of the erosion process during the field experiment. Soil samples from 17 locations on this flat surface contain significant amounts of highly erodible particles with diameters in the 200–300µm and 100–150µm size ranges. Aeolian particles collected in BSNE sand traps located at different heights near the surface, exhibit a bimodal size distribution similar to that of the erodible fraction of the soils; the abundance of the fine class increasing with height. Small stones that have a spatially variable distribution can locally reduce the intensity of wind erosion. The mineralogical composition of moving particles is similar to that of the soils, with quartz, feldspar and calcite as the most important minerals, followed by clay minerals, gypsum and amphibole. A value of u*tis calculated for each soil particle size class. Subsequently, the elementary contribution of each size class to the horizontal flux is calculated using White (1979)'s equation and the total flux is finally obtained by integration. The saltation model successfully reproduces the variability of the wind erosion process during the field experiment, but over-estimates the vertically integrated mass fluxes measured in situ by two orders of magnitude.