Geochemical characteristics and metallogenic geological conditions of pegmatite type lithium polymetallic ore in Rongxuka, Sichuan Province

Through the analysis on the geochemical characteristics of the intermediate acid-acid intrusive rocks and pegmatites in the pegmatite type lithium polymetallic ore deposit in Rongxuka of Sichuan Province, the authors discussed the metallogenic geological conditions of stratigraphy, tectonics and magmatites. The results show that the intermediate acid-acid intrusive rocks in Rongxuka area are calc-alkaline and quasi-aluminum rocks, and belong to the I-type granite series. The pegmatites are calc-alkaline and strongly peraluminous rocks, and there are significant geochemical differences in rare earth and trace elements between the intermediate acid-acid intrusive rocks and pegmatites. The intermediate acid-acid intrusive rocks were formed in post-collision tectonic setting, which might be related to the collisional orogeny of the Songpan-Ganzi orogenic belt. The material source might be partial melting of crustal material mixed with a small amount of mantle composition. Pegmatites and intermediate acid-acid intrusive rocks may be products of differentiation and evolution of homogenous magma. The folds, faults and domes formed by the regional napping provided a favorable space for the filling of ore-bearing hydrothermal fluids and enrichment of ore-forming elements. The melts enriched by volatile and rare metals intruded into wall rocks, and the low-permeability mudstones limited the loss of heat and materials favorable for ore accumulation. Then the ore-containing melts solidified and the rare metal pegmatite veins formed.