Weathering-pedogenesis characteristics and influencing factors of the earth’s critical zone: A case study of Xichang Region

As the hinterland of the Daliangshan Mountains, Xichang area is a crucial ecological security barrier in upper reaches of the Yangtze River. Quality of its ecological environment has a significant impact on the ecological, industrial, and agricultural activities within the Yangtze River basin. In recent years, regional eco-geological research has increasingly focused on the earth’s critical zone. However, process of weathering and pedogenesis, which plays multiple roles within the critical zone’s series of processes, remains understudied in this region. This study discusses and analyzes the characteristics and influencing factors of weathering and pedogenesis in the earth’s critical zone of the Xichang area, based on geochemical data from 151 systematically collected rock-soil profiles. The results indicate that: 1) The indicator elements of weathering and pedogenesis—SiO2, Al2O3, Fe2O3, FeO, CaO, MgO, K2O, Na2O, MnO, TiO2, and P2O5—exhibit both leaching and enrichment relative to the average composition of the Upper Continental Crust (UCC). This is primarily attributed to differences in element mobility and the process of secondary enrichment during weathering and pedogenesis. 2) Multiple chemical weathering indices collectively indicate that the study area is in a moderate stage of chemical weathering, characterized by high soil maturity. 3) The process and characteristics of weathering and pedogenesis are influenced by a combination of factors. Future research on this topic must prioritize addressing the dual impacts of climate change and human activities. Based on a large volume of sample data from diverse end-members, this study investigates the characteristics of weathering and soil formation and their influencing factors in the study area. The findings not only provide a valuable supplement to the understanding of weathering and soil formation characteristics and geochemical element migration mechanisms in the Xichang mountainous area, but also offer fundamental data and a scientific basis for ecological environment construction, regional economic development, ecological protection, scientific and rational utilization of land resources, and response to climate change in the region.