The global distribution of clay minerals is intricately linked with climatic conditions and bedrock composition, which interact to control the weathering intensity of silicate and other minerals. However, the quantitative relationship between clay minerals and climate is not well understood, partly due to the lack of quantitative assessments of the role of the various factors responsible for clay mineral formation. Here we examine the quantitative relationship between soil clay minerals and climatic factors on the global scale, by extrapolating clay mineral abundances to a large scale. We found that mean annual precipitation (MAP) is the first order control on the global clay mineral distribution, while mean annual temperature (MAT), elevation, slope, lithology, upland hillslope soil thickness (UHST), and upland hillslope regolith thickness (UHRT) have secondary roles or localized impacts on clay mineral distributions. We found that precipitation thresholds exist in weathering intensity and clay mineral formation: (1) Illite decreases monotonically and kaolinite increases monotonically with increasing MAP below the threshold of 1800–2000 mm, whereas gibbsite increases monotonically with increasing MAP below the threshold of 2200–2400 mm. (2) Smectite and Fe oxides increase with increasing MAP below the threshold of 600–800 mm, and then decrease with increasing MAP between 600 and 800 mm and 1800–2000 mm. (3) All clay minerals are insensitive to extremely high MAP, above 1800–2000 mm. We suggest that paleoprecipitation can be semi-quantitatively reconstructed based on variations in the relative contents of clay minerals, which can be used as a proxy indicator of wet and dry variations for paleoclimate studies.

中文翻译：

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降水是土壤粘土矿物全球分布的主要控制因素


粘土矿物的全球分布与气候条件和基岩成分密切相关，它们相互作用控制硅酸盐和其他矿物的风化强度。然而，粘土矿物与气候之间的定量关系尚不清楚，部分原因是缺乏对粘土矿物形成的各种因素的作用的定量评估。在这里，我们通过大范围推断粘土矿物丰度，研究全球范围内土壤粘土矿物与气候因素之间的定量关系。我们发现年平均降水量（MAP）是全球粘土矿物分布的一级控制因素，而年平均温度（MAT）、海拔、坡度、岩性、山坡土壤厚度（UHST）和山坡风化层厚度（UHRT） ）对粘土矿物分布具有次要作用或局部影响。我们发现，风化强度和粘土矿物形成存在降水阈值：（1）在1800~2000 mm阈值以下，伊利石随MAP的增加单调减少，高岭石单调增加，而三水铝石在2200~2400 mm阈值以下，随着MAP的增加单调增加。毫米。 （2）在600~800 mm阈值以下，蒙脱石和Fe氧化物随着MAP的增加而增加，然后在600~800 mm和1800~2000 mm之间，随着MAP的增加而减少。 (3) 所有粘土矿物对高于 1800-2000 mm 的极高 MAP 不敏感。我们建议可以根据粘土矿物相对含量的变化来半定量重建古降水，这可以作为古气候研究干湿变化的代理指标。