The provenance characteristics and lithium enrichment mechanism of bauxite-type lithium-rich clay in Yunnan-Guizhou area.

Key words: 
• bauxite-type lithium-rich claystone /
• provenance characteristics /
• lithium enrichment mechanism /
• Yunnan-Guizhou area

Abstract: Bauxite-type lithium-rich claystone deposits with great ore-forming potential have been found in the bauxite-bearing strata formed in different geological periods in the Yunnan-Guizhou area of southwestern China, but the current understanding of the material sources and lithium enrichment mechanisms of these bauxite-type lithium-rich claystones in these areas is still significantly insufficient. This study carried out a comparative analysis of the mineral composition, major trace and rare earth element composition of the bauxite-type lithium-rich claystone series of the Early Permian Daoshitou Formation in Yunnan and the Early Carboniferous Jiajialu Formation in Guizhou, and combined with the previous research results, systematically discussed the provenance characteristics and the limiting factors that caused the abnormal lithium enrichment of these two sets of bauxite-type lithium-rich claystones that formed in different ages but have extremely similar lithofacies characteristics. The results show that the difference in provenance characteristics between the Jiajialu Formation and the Daoshitou Formation lithium-rich claystones in Guizhou and Yunnan has a significant impact on their respective lithium characteristics. Generally, the formation of the Jiajialu Formation claystone with relatively low lithium content is closely related to the weathering and erosion of the impure dolomite of the underlying Loushanguan Group, and its original source may be the Mesoproterozoic-Middle Proterozoic intermediate-acidic magmatic rocks, and it is significantly affected by the magnesium-iron components. The formation of the Daoshitou Formation claystone with relatively high lithium content in Yunnan is significantly affected by the recycled material of the Ordovician sedimentary rock series, and the source connection with the underlying carbonate rock strata is weak. At the same time, its original source is obviously dominated by intermediate-acidic magmatic rocks. In addition, the lithium-bearing minerals in the lithium-rich claystones in the Yunnan-Guizhou area may be kaolinite or illite minerals, and the drainage of the basin during the sedimentary period and the coexistence effect of ions in the water body have played an important role in the enrichment of lithium in the clay. The relevant understanding of this study has important significance for deepening the ore-forming process and limiting mechanism of clay-type lithium deposits.