Geochronological and geochemical constraints on magmatic evolution and mineralization of the northeast Ke’eryin pluton and the newly discovered Jiada pegmatite-type lithium deposit, Western China

• DOI: 10.1016/j.oregeorev.2022.105164
• Publication Date: 2022-10-18T08:10:02Z
• Authors: Xin Li; Hongzhang Dai; Denghong Wang; Shanbao Liu; Genhou Wang; Chenghui Wang; Fan Huang; Haiyang Zhu
• Keywords: Pegmatite; Petrogenesis; Fractional crystallization (geology)

The Ke'eryin ore field in the Songpan-Garze Fold Belt (SGFB), western China, is an important area of pegmatite-type lithium accumulation. However, petrogenesis pegmatites and their genetic relationships with neighboring granitic pluton are still a topic debate. In this work, LA-MC-ICP-MS zircon columbite-tantalite U-Pb dating, whole-rock mica geochemical analysis, isotopic analysis newly discovered Jiada deposit were performed. Zircon dating biotite K-feldspar granite (BG), fine-grained two-mica monzogranite (FTG), medium-grained (MTG) composite yielded crystallization ages 219.5 ± 0.7 Ma, 212.8 1.1 209.1 respectively. Columbite-tantalite albite-spodumene type pegmatite (ASP) from 204.7 1.0 Ma. results show that mineralization was temporally closest to MTG emplacement. Combined regional magmatic evolution sequence, it suggested emplaced during period transition tectonic compression extension under effect lithospheric delamination post-collision. Geochemically, compositional variation major elements minerals indicate BG, FTG, AP (albite pegmatite) ASP formed via same continuous process. increasing Li, Rb, Cs, Nb, Ta concentrations decreasing K/Rb, K/Cs, Nb/Ta ratios degree differentiation increased order BG-FTG-MTG-AP-ASP, indicating could be parent rock pegmatites. increase δ7Li values muscovites through provides new evidence support fact fractional played significant role formation deposit. Alkali metal (e.g., K, Cs) MTG, AP, followed Rayleigh fractionation law, Rayleigh-type process occurred. modelling these alkali showed produce magma melt extreme (∼98–99 % fractionation). Taken together associated geological evidence, aforementioned features favorable setting prolonged jointly contributed