Pedogenic clay formation from allochthonous parent materials in a periglacial alpine critical zone
Pedogenic clay formation from allochthonous parent materials in a periglacial alpine critical zone
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DOI：
10.1016/j.catena.2021.105324
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发表时间：
2021-08
期刊：
影响因子：
6.2
通讯作者：
J. Munroe;P. Ryan;A. Proctor
中科院分区：
文献类型：
--
作者：
J. Munroe;P. Ryan;A. Proctor
该项目调查了美国犹他州尤因塔山脉高山地区石英岩基岩上方风化层中粘土矿物的起源。地球化学和矿物学分析表明，这些粘土是通过两种外来母质的化学风化形成的。富含蒙皂石的粘土，其镁丰度明显高于现代尘埃或当地基岩，是由渐新世盆地和山脉喷发中心沉积的安山灰层风化而形成的。相比之下，不同阶段的层间高岭石-伊利石-蒙脱石粘土是通过至今仍在继续的风成过程中产生的云母和长石的风化而形成的。当地基岩作为粘土新形成的母质似乎只发挥了次要作用。这些结果表明，即使在寒冷气候的土壤和覆盖耐风化基岩的风化层中，成土粘土也很常见。他们还强调，土壤和风化层中的粘土库存可以反映现代气候条件建立之前运行的过程，并加强外源矿物输入在高山关键带功能中发挥的关键作用。
This project investigated the origin of clay minerals in regolith present above quartzite bedrock in the alpine zone of the Uinta Mountains, Utah, USA. Geochemical and mineralogical analysis indicates that these clays formed through chemical weathering of two allochthonous parent materials. Smectite-rich clays, with Mg abundance distinctly higher than modern dust or local bedrock, formed through weathering of andesitic ash layers that were deposited during the Oligocene from eruptive centers in the Basin and Range. In contrast, various stages of interstratified kaolinite-illite–smectite clays have formed through weathering of mica and feldspar delivered by eolian processes that continue today. Local bedrock appears to have played only a minor role as a parent material for clay neoformation. These results demonstrate that pedogenic clay can be common even in cold climate soils and regolith overlying weathering resistant bedrock. They also emphasize that the clay inventory in soil and regolith can reflect processes that operated before modern climatic conditions were established, and reinforce the key role played by exogenous mineral inputs in the functioning of the alpine critical zone.