| 东昆仑东段将军墓含矿岩体锆石U-Pb年代学、地球化学特征及其地质意义 |
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| 引用本文： | 俞军真,郑有业,许荣科,侯维东,蔡鹏捷.东昆仑东段将军墓含矿岩体锆石U-Pb年代学、地球化学特征及其地质意义[J].地球科学,2020,45(4):1151-1167. |
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| 作者姓名： | 俞军真 郑有业 许荣科 侯维东 蔡鹏捷 |
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| 作者单位： | 1.中国地质大学资源学院, 湖北武汉 430074 |
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| 基金项目： | 教育部长江学者和创新团队发展计划项目IRT14R54中央公益性基础地质调查项目DD20190069 |
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| 摘 要： | 将军墓含矿花岗闪长斑岩位于东昆仑造山带东段.通过岩石地球化学、锆石U-Pb年代学、Lu-Hf同位素研究，结果表明，含矿花岗闪长斑岩LA-ICP-MS锆石U-Pb年龄为218.8±1.3 Ma，形成于晚三叠世.含矿花岗闪长斑岩SiO2含量为65.23%~67.25%，MgO含量1.50%~1.59%，Al2O3含量15.30%~15.75%，K2O/Na2O比值1.00~1.20，Mg#值43~44.表现富硅、富铝、富钾特征，显示高钾钙碱性系列；岩石具有轻重稀土分馏和轻稀土富集及负Eu异常特征，富集大离子亲石元素（LILE），如Th、U、Rb、K；亏损高场强元素（HFSE），如Nb、P、Zr等；锆石εHf（t）=-1.7~+1.01，TDM2=1 064~1 214 Ma，反映源区主体为中元古代下地壳.综合年代学、岩石学和地球化学证据，显示将军墓含矿花岗闪长斑岩源于中元古代下地壳重熔，并有少量地幔岩浆加入而发生不完全混合，含少量暗色微粒包体的含矿岩石.将军墓含矿花岗闪长斑岩形成于东昆仑晚三叠世碰撞后伸展环境，是东昆仑晚三叠世壳幔相互作用成岩-成矿的体现.该岩体不仅仅是东昆仑古特提斯构造岩浆事件的产物，同时具备良好的成矿条件，为东昆仑晚三叠世岩浆作用研究和寻找与之有关的斑岩型或热液型多金属矿床提供重要的证据.
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| 关 键 词： | 东昆仑东段 将军墓含矿花岗闪长斑岩 锆石U-Pb年龄 暗色微粒包体 岩石学 |
| 收稿时间： | 2019-06-06 |
Zircon U-Pb Chronology,Geochemistry of Jiangjunmu Ore-Bearing Pluton,Eastern Part of East Kunlun and Their Geological Significance |
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| Abstract: | Jiangjunmu ore-bearing granodiorite porphyry is located in the eastern part of East Kunlun orogenic belt. In this paper,zircon U-Pb dating and Lu-Hf isotopes,whole-rock major and trace elements of ore-bearing granodiorite porphyry are presented to discuss their geochronology and genesis. The results show that the ore-bearing granodiorite porphyry was formed at the Late Triassic with the age of 218.8±1.3 Ma. It has contents of SiO2(65.23%-67.25%),MgO(1.50%-1.59%),Al2O3(15.30%-15.75%) with K2O/Na2O ratios ranging from 1.00 to 1.20 and Mg# values ranging from 43 to 44. The ore-bearing granodiorite porphyries are characterized by high silicon,aluminum and high-potassium,belonging to the high-potassium rock. Meanwhile,they are enriched in large ion lithophile elements (LILEs) such as Th,U,Rb and K,and depleted in high field strength elements (HFSE) such as Nb,P and Zr. Hf isotopic compositions of the ore-bearing granodiorite porphyry (εHf(t)=-1.7-+1.01,TDM2=1 064-1 214 Ma),indicating that their parental magmas were derived from the Middle Proterozoic lower crust. Coupled with the petrography of a small number of mafic microgranular enclaves,geochronology,petrology and geochemistry data indicate that ore-bearing granodiorite porphyry originated from the mixing of dominating re-melting of Middle Proterozoic lower crust and a small amount of mantle-derived materials. The ore-bearing granodiorite porphyry was formed in the post-collisional orogenic extensional setting,indicative of the crust-mantle diagenesis and mineralization at Late Triassic in the East Kunlun. It is not only the product of the Paleo-Tethys tectonic and magmatic event in the East Kunlun,but also has good metallogenic conditions,which provides important evidence for the study of the Late Triassic magmatism in the East Kunlun and search for porphyry or hydrothermal polymetallic deposits. |
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