| 西藏多不杂斑岩铜(金)矿床磁铁矿元素地球化学特征及其对成矿过程的指示 |
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| 关键词:Duobuza copper (gold) deposit porphyry type magnetite mineralization |
| 基金项目:国家自然科学基金项目“西藏多龙巨型铜金矿集区铁格隆南矿床的改造;保存机制: 多体系低温热年代学约束”(编号: 42002103);国家重点研发计划项目“西藏铜多金属资源基地绿色勘查与增储示范”(编号: 2022YFC2905001) |
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| Elemental Geochemical Characteristics of Magnetite and Its Indication of Mineralization Process in the Duobuza Porphyry Copper (Gold) Deposit, Tibet |
| The Duobuza copper (gold) deposit is an important porphyry copper deposit located in the Duolong ore district of Tibet. Detailed core logging and petrographic studies show that the Duobuza copper (gold) deposit develops four types of magnetite. Magnetite-1 (Mt1) with grayish-white reflective color, anhedral grain, and some are trapped in the biotite. Magnetite-2 (Mt2) with pinkish-brown reflective color, subhedral to anhedral grain, with edges that are replaced by hematite, and containing a small amount of chalcopyrite. Magnetite-3 (Mt3) is pinkish-brown, euhedral to anhedral grain, small in size with smooth surface, and mainly occurs in hornfelization alteration. Magnetite-4 (Mt4) is dark gray, and its fissures and intergranular spaces are replaced by pyrite and chalcopyrite. Mt1 and Mt2 belong to the magmatic magnetite or magmatic-hydrothermal magnetite transitional types, while Mt3 and Mt4 belong to the magmatic-hydrothermal magnetite transitional types. Mt1, Mt2, and Mt4 magnetite formed at temperatures ranging from roughly 300 °C to 500 °C, while Mt3 formed at temperatures ranging from roughly 200 °C to 500 °C, which is significantly lower than those of the other three types of magnetite. The four types of magnetite have marked geochemical differences. Mt1 is characterized by high Ti and V, low Mn, and low oxygen fugacity; Mt2 is characterized by low V, high Mn, and high oxygen fugacity; Mt3 is characterized by low temperature, low Mn, Al, and positive correlation between Mn and Al content and Ti; Mt4 is characterized by low V, high Mn, Si, Al, and high oxygen fugacity. Mt1 is formed first, while Mt3 is formed last. The magnetite with high Mn and low V is an indicator of copper mineralization in the Duobuza deposit. |
| FU Xue-lian,TANG Ju-xing,YANG Huan-huan,WANG Qin,LIANG Xin-juan,ZHANG Qi,DONG Yu-jie,SONG Jia-jun,LI Jian-li,WANG Jia-xin,ZHANG Rong-kun.2023.Elemental Geochemical Characteristics of Magnetite and Its Indication of Mineralization Process in the Duobuza Porphyry Copper (Gold) Deposit, Tibet[J].Acta Geoscientica Sinica,44(3):498-510. |
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