Origin of Pingqiao fluorite-lithium deposit in Guizhou, southwest Yangtze Block, China

Lithium (Li) stands as a critical mineral resource, finding applications across various industries such as new energy, medicine, and optoelectronics (Bowell et al., 2020). Fluorite emerges as a strategic mineral, playing a pivotal role as a significant non-metal resource in various countries (Kesler et al., 2012). Recently, significant discoveries of fluorite and lithium have been made within the Early Permian strata in the Liuzhi area of the southwestern Yangtze Block, China, with reserves reaching a large scale (fluorite > 400 Kt; lithium > 100 Kt). This discovery suggests a potentially new type of lithium deposit unrelated to magmatism, sedimentary, or brine-related origins. The rare mineral system exhibiting fluorite and lithium associations holds substantial economic value and research significance. This study aims to investigate the origin of the Pingqiao F-Li deposit in the Liuzhi area through field geological investigation, mineralogy and element geochemistry, with the intention of discovering similar deposits elsewhere. The fluorite in the study area demonstrates an apparent hydrothermal origin, with fluorine deriving from deep F-rich strata and fluid-mediated water-rock reactions (Zou et al., 2021, 2022). Similarly, the lithium ore body origin from hydrothermal characteristics, being preserved on both sides of a fault, with decreasing Li content moving away from the fault (Zou et al., 2022). Abundant silicified alteration was observed within the deposit, indicating significant hydrothermal activity. Lithium concentration is found within quartz resulting from silicification, indicating the presence of significant Li within the hydrothermal system. Cookeite stands out as the primary carrier mineral for lithium in this deposit (Hui et al., 2021). Cookeite formation occurs in medium- and low-temperature (Guo et al., 2019), aligning with the homogenization temperature of fluorite fluid inclusion (110-240 ℃, Zou et al., 2022). In conclusion, both the fluorite and lithium within the Pingqiao F-Li deposit likely originated from hydrothermal processes. Keywords: Fluorite-lithium; Southwest Yangtze Block; Origin; hydrothermal References Bowell, R.J., Lagos, L., De Los Hoyos, C.R., Declercq, J., 2020. Classification and characteristics of natural lithium resources. Elements. 16, 259–264. Guo, W.M., Wang, D.H., Li, P., Li, J.K., Shu, Z.M., Zhang, W.S., 2019. Sb-Li assemblages: Rare assemblages of mineralization and the occurrence of lithium. Acta Geol. Sin. 93, 1296–1308 (in Chinese with English abstract). Hui, B., Gong, D.X., Chen, W., Lai, Y., 2021. Study on the occurrence of lithium in sedimentary lithium deposits in Liuzhi area Guizhou Province. Nonfer Metals (mineral pro sect). 2, 1–4 (in Chinese with English abstract). Kesler, S.E., Gruber, P.W., Medina, P.A., Keoleian, G.A., Everson, M.P., Wallington, T.J., 2012. Global lithium resources: Relative importance of pegmatite, brine and other deposits. Ore Geol. Rev. 48, 55–69. Zou, H., Li, Q.L., Bagas, L., Wang, X.C., Chen, A.Q., Li, X.H., 2021. A Neoproterozoic low-δ18O magmatic ring around South China: Implications for configuration and breakup of Rodinia supercontinent. Earth Planet. Sci. Lett. 575, 117196. Zou, H., Xiao, B., Gong, D.X., Huang, C.C., Li, M., Yu, L.M., Tian, E.Y., Liu, C.M., Chen, H.F., Hu, C.H., 2022. Origin and tectonic setting of Pingqiao fluorite-lithium deposit in the Guizhou, southwest Yangtze Block, China. Ore Geol. Rev. 143, 104755.