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Large‐Scale Cenozoic Wind Erosion in the Puna Plateau: The Salina del Fraile Depression
Journal of Geophysical Research: Earth Surface ( IF 3.5 ) Pub Date : 2020-08-19 , DOI: 10.1029/2020jf005682
Mitchell McMillan 1 , Lindsay M. Schoenbohm 1, 2
Affiliation  

Wind erosion is integral to the evolution of arid landscapes on Earth and Mars, but the nature of long‐term wind erosion of bedrock is poorly understood. Here we describe the Salina del Fraile (SdF) depression in the Puna Plateau of the Central Andes, NW Argentina, as a landform excavated by wind over several million years. New structural cross sections and a compilation of chronostratigraphic ages rule out the hypothesis that the depression was created by transtensional tectonics. Dated remnant lacustrine and alluvial deposits in the floor of the depression constrain the rate and timing of erosion. Late Oligocene‐Miocene compressional folding uplifted friable strata that were preferentially eroded, resulting in the high‐relief (900 m) depression. Up to 1.95 km and an average of 1.05 km of strata were eroded during the last 8.2 to 17 Ma, at rates of 0.06 to 0.23 mm/yr. These rates are similar to long‐term average wind erosion rates reported in other regions. Coarse‐grained eolian megaripples, yardangs, and elongated ridges indicate ongoing eolian abrasion and deflation, aided by salt weathering, of the floor of the depression. Megaripple migration across stony lag surfaces exposes fresh bedrock to continued erosion. The SdF also contains kilometer‐scale mesas and ridges that we interpret as erosional remnants. These landforms are similar to megayardangs and erosional topography identified on the lower flanks of Mount Sharp, Gale crater, Mars. In such hyperarid landscapes characterized by lithologic heterogeneities, high‐relief landforms can be generated and sustained by wind erosion, without significant fluvial or glacial incision.

中文翻译:

普纳高原大范围新生代风蚀:盐沼脆弱地带

风蚀是地球和火星上干旱景观演变不可或缺的组成部分,但人们对基岩长期风蚀的性质了解甚少。在这里,我们将阿根廷西北部安第斯山脉中部普纳高原的盐沼(SdF)凹陷描述为经过数百万年的风蚀而形成的地貌。新的结构剖面和年代地层年龄的汇编排除了这一假设,即该凹陷是由张性构造所造成的。凹陷底部陈旧的湖相和冲积物限制了侵蚀的速度和时间。渐新世-中新世晚期压缩褶皱抬高了易受侵​​蚀的易碎地层,导致了高浮雕(900 m)凹陷。在最后8.2到17 Ma内,长达1.95 km的地层平均被侵蚀了1.05 km,以0.06至0.23毫米/年的速度。这些速率与其他地区的长期平均风蚀率相似。粗粒的风积巨波纹,亚当岗和拉长的山脊表明凹陷底部持续不断的风积磨损和放气,并伴随着盐的风化。跨石质滞留面的巨型波纹迁移使新鲜的基岩暴露于持续的侵蚀。SdF还包含千米级的台地和山脊,我们将其解释为侵蚀残余物。这些地貌与火星大风火山口的夏普山下翼的大型岩浆岩和侵蚀地形相似。在这种以岩性非均质性为特征的高干旱地貌中,可以通过风蚀产生并维持高起伏地貌,而无需进行明显的河流或冰川切割。这些速率与其他地区的长期平均风蚀率相似。粗粒的风积巨波纹,亚当岗和拉长的山脊表明凹陷底部持续不断的风积磨损和放气,并伴随着盐的风化。跨石质滞留面的巨型波纹迁移使新鲜的基岩暴露于持续的侵蚀。SdF还包含千米级的台地和山脊,我们将其解释为侵蚀残余物。这些地貌与火星大风火山口的夏普山下翼的大型岩浆岩和侵蚀地形相似。在这种以岩性非均质性为特征的高干旱地貌中,可以通过风蚀产生并维持高起伏地貌,而无需进行明显的河流或冰川切割。这些速率与其他地区的长期平均风蚀率相似。粗粒的风积巨波纹,亚当岗和拉长的山脊表明凹陷底部持续不断的风积磨损和放气,并伴随着盐的风化。跨石质滞留面的巨型波纹迁移使新鲜的基岩暴露于持续的侵蚀。SdF还包含千米级的台地和山脊,我们将其解释为侵蚀残余物。这些地貌与火星大风火山口的夏普山下翼的大型岩浆岩和侵蚀地形相似。在这种以岩性非均质性为特征的高干旱地貌中,可以通过风蚀产生并维持高起伏地貌,而无需进行明显的河流或冰川切割。粗粒的风积巨波纹,亚当岗和拉长的山脊表明凹陷底部持续不断的风积磨损和放气,并伴随着盐的风化。跨石质滞留面的巨型波纹迁移使新鲜的基岩暴露于持续的侵蚀。SdF还包含千米级的台地和山脊,我们将其解释为侵蚀残余物。这些地貌与火星大风火山口的夏普山下翼的大型岩浆岩和侵蚀地形相似。在这种以岩性非均质性为特征的高干旱地貌中,可以通过风蚀产生并维持高起伏地貌,而无需进行明显的河流或冰川切割。粗粒的风积巨波纹,亚当岗和拉长的山脊表明凹陷底部持续不断的风积磨损和放气,并伴随着盐的风化。跨石质滞留面的巨型波纹迁移使新鲜的基岩暴露于持续的侵蚀。SdF还包含千米级的台地和山脊,我们将其解释为侵蚀残余物。这些地貌类似于火星大风火山口的夏普山下翼的巨yard和侵蚀地形。在这种以岩性非均质性为特征的高干旱地貌中,可以通过风蚀产生并维持高起伏地貌,而无需进行明显的河流或冰川切割。跨石质滞留面的巨型波纹迁移使新鲜的基岩暴露于持续的侵蚀。SdF还包含千米级的台地和山脊,我们将其解释为侵蚀残余物。这些地貌类似于火星大风火山口的夏普山下翼的巨yard和侵蚀地形。在这种以岩性非均质性为特征的高干旱地貌中,高起伏地貌可以通过风蚀而产生并维持,而没有明显的河流或冰川切缝。跨石质滞留面的巨型波纹迁移使新鲜的基岩暴露于持续的侵蚀。SdF还包含千米级的台地和山脊,我们将其解释为侵蚀残余物。这些地貌类似于火星大风火山口的夏普山下翼的巨yard和侵蚀地形。在这种以岩性非均质性为特征的高干旱地貌中,高起伏地貌可以通过风蚀而产生并维持,而没有明显的河流或冰川切缝。
更新日期:2020-09-03
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