Soil Magnetic Characteristics of Weakly Magnetic Sandstones in Tropical and Subtropical Yunnan and Their Environmental Significance

As an important surface ecosystem of the earth, the soil records abundant geological and environmental information. During the formation and development of soil, the magnetic minerals it contains will also change. Therefore, soil magnetism is related to the climatic environment information of the soil formation period and can be used to reconstruct the paleoenvironment. Currently, the research on soil magnetism in temperate semi-arid areas and its corresponding climatic and environmental indicators is relatively mature; however, the climatic and environmental indicators of soil magnetism in tropical and subtropical areas remain controversial and need further research. In this study, magnetic and diffuse reflectance spectroscopy were used to analyze the weathering crust of sandstone in different climatic zones in Yunnan. The results show that: (1) the three selected ferrimagnetic minerals in weathering crust profiles are magnetite and maghemite; the antiferromagnetic minerals are goethite and hematite. The mai