| 南岭威溪矿区花岗岩的岩石成因——来自地球化学、锆石U-Pb年代学及Hf同位素制约 |
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| 关键词:tungsten polymetallic deposit S-type granite zircon U-Pb dating Hf isotopes magma source |
| 基金项目:本文由湖南省自然科学基金(编号: 2024JJ8318; 2025JJ80404; 2025JJ80405; 2025JJ80045)、有色金属成矿预测与地质环境监测教育部重点实验室(中南大学)开放基金(编号: 2023YSJS16)、国家科技重大专项项目子课题(编号: 2025ZD1007803)、国地球深部探测与矿产资源勘查国家科技重大专项(编号: 2023YFC2906405)和湖南省自然资源重大科研项目(编号: 20240102DZ)联合资助。 |
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| Genesis of Granites in the Nanling Weixi Mining Area: Constraints from Geochemistry, Zircon U-Pb Geochronology, and Hf Isotopes |
| Granitic mylonite and biotite monzogranite are exposed in the Weixi mining area. Geochemical analyses indicate that the former is weakly to strongly peraluminous (A/CNK=1.10–1.83), whereas the latter is metaluminous to weakly peraluminous (A/CNK=1.00–1.08). The granitic mylonite exhibited a pronounced negative Eu anomaly (δEu=0.37–0.53) and a “seagull-shaped” rare earth element pattern, consistent with the characteristics of crust-derived granites. Trace-element data showed enrichment in Rb, Th, U, Zr, and Hf, and depletion in Ba, Sr, P, and Ti. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) zircon U-Pb dating yielded ages of (825±3) Ma (MSWD=0.04) for the granitic mylonite and (431±2) Ma (MSWD=0.06) for the biotite monzogranite, corresponding to Neoproterozoic and Caledonian magmatic activities, respectively. Zircon Hf isotope analyses showed εHf(t) values ranging from –4.05 to 11.27 (mean: –1.38) for the granitic mylonite, suggesting involvement of mantle-derived material in the magma source, whereas εHf(t) values for the biotite monzogranite ranged from –9.13 to –3.31 (mean: –6.91), indicating derivation from the partial remelting of ancient crustal components. Two-stage zircon Hf model ages (TDM2) of 1 472–1 824 Ma and 1 473– 1 794 Ma, respectively, point to significant contributions from Mesoproterozoic crustal material. Integrated geochemical and isotopic evidence suggests that the granitic mylonite formed in an extensional tectonic setting during the rifting of the Rodinia supercontinent, whereas the biotite monzogranite crystallized in a post-collisional extensional regime related to the Caledonian orogeny. Tungsten polymetallic mineralization in this region is primarily associated with Caledonian granite, which provided essential hydrothermal fluids and metallogenic material for skarn-type W polymetallic deposits. The Neoproterozoic pluton likely contributed to early enrichment of ore-forming elements (W). |
| MA Huiying,CHEN Jianfeng,DU Yun,WEN Chunhua,XIANG Ke,HUANG Jianzhong,TIAN Lei,ZENG Guangqian,LIANG Enyun,HUANG Leqing,LI Xiangyu,WANG Lingjue.2026.Genesis of Granites in the Nanling Weixi Mining Area: Constraints from Geochemistry, Zircon U-Pb Geochronology, and Hf Isotopes[J].Acta Geoscientica Sinica,47(3):565-579. |
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