Southern Sichuan, located in the middle- outer zone of the Permian Emeishan Large Igneous Province, is extensively distributed with claystones from the Lower Permian Longtan Formation. These claystones, which are related to igneous rock weathering and deposition, have a geological background and metallogenic conditions suitable for forming lithium and other critical metal resources. This paper presents a systematic geological survey of the lower part of the Upper Permian Longtan Formation in the Xingwen area of southern Sichuan.Chemical analysis of samples from the study area and drill cores was conducted to determine the distribution and enrichment of lithium and other elements in the claystones.Additionally, the mineral composition of the lithium- rich claystones was analyzed using powder crystal X- ray diffraction (XRD), and the distribution characteristics of elements at the micrometer scale were analyzed using a focused- ionbeam and time- of- flight secondary ion mass spectrometer (FIB- TOF- SIMS). The results show that the claystones in the lower part of the Longtan Formation are enriched in Li, Ga, Nb, and other elements, making them a valuable source of multiple critical metals with good ore- forming potential and prospecting prospects. These claystones originate from the weathering processes of volcanic rocks within the Emeishan Large Igneous Province.The lithium- rich rocks are mainly pyrite- bearing kaolinitic claystones, witha sedimentary environment in the saline lagoon of the transitional zone between sea and land. The Li content is closely related to the chemical weathering intensity (CIA index), exhibiting the characteristics of weathering- sedimentary deposits. Lithium, apart from being present in lepidolite to a small extent, is mainly adsorbed in the montmorillonite phase of claystones, with some entering the mineral structure of montmorillonite andillite. In addition to weathering release from volcanic rocks, a portion of lithium potentially originates directly from coastal shallow groundwater, contributing to the formation of high- grade lithium- bearing mica within lithium- rich claystones.