Objectives:The Wangpo Shale, representing Guadalupian—Lopingian Boundary (GLB) deposits, occurs at the base of the Wujiaping Formation in the Liangshan area of Shaanxi Province. It was traditionally interpreted as a terrigenous shale bed related to a paleoweathering surface, suggesting a regression event after the Maokouan Stage. Methods: We carried out an investigation in detail for Wangpo Shale and collected the rock and fossil samples. the analysis of X ray diffraction (XRD), paleontology, petrography and lithology are carried out. Results:X ray diffraction (XRD) analysis shows that the Wangpo Shale consists predominantly of montmorillonite (71%), heulandite (23%), and quartz (6%), suggesting an origin from volcanic glass. Petrographic analysis shows that the Wangpo Shale is primarily composed of altered minerals montmorillonite and heulandite with residual tuffaceous structures and vitric pyroclast. Abundant brachiopod fossils occur in the Wangpo Shale, suggesting deposition in a marine environment. Conclusions: These data indicate that the Wangpo Shale is a typical bentonite, derived from volcanic ash fall that was subsequently altered in a marine environment. Sudden ash fall may have destabilized the shallow marine ecosystems at the Guadalupian—Lopingian Boundary, resulting in an ecological crisis for Permian brachiopods.