Acta Petrologica et Mineralogica

Catastrophic events contain important geological information, and their relics have economic and scientific value. Discovering and studying catastrophic events is one of the methods to solve geological problems and also a way to improve the understanding of geological science. This article lists the main catastrophic events of the Permian bauxite rock series in western Guangxi basing on field investigations, microscopic feature studies, and analysis of heavy metal elements in the bauxite-bearing rock series, and explains their formation. The main catastrophic events in bauxite-bearing rock formations are volcanic ash season, heavy metal anomalies and earthquake episode. The duration span of volcanic ash deposition can extend to 10 Ma, and the lithology of volcanic ash varies from basic to acidic, showing the arc-related calc-alkaline magma series. Compared to bauxite ore concentration areas in the North China and North Guizhou, the bauxite-bearing rock series in studied sections of western Guangxi is strongly enriched in Cr, with an average value of 400×10^-6 to 900×10^-6, whereas Ni is strongly enriched in some sections, with an average value of 300×10^-6~600×10^-6, Cd is enriched in most sections, but Co is enriched in few sections. In addition, Sb and As are greatly enriched in the rocks with felsic volcanic ash. Six elements including Cr, Ni, Cd, Sb, As, and Co constitute heavy metal anomalies. The seismic relics include soft deformation, seismic turbidite, and small graben, etc. The triggering factors for volcanic ash fall and seismic episode were probably the subduction of the Indosinian plate beneath the southwestern margin of the South China plate, which formed island arc magmas and volcanic eruptions, meanwhile the back arc basin tension caused earthquakes. Volcanic ash not only provides substances such as aluminium and iron for bauxite-bearing rock series, but also heavy metals which generated to heavy metal anomalies

catastrophic events; bauxite-bearing rock series; volcanic ash; heavy metals; western Guangxi