| 粤北长江铀矿田辉长闪长岩的岩石成因及其与铀成矿的关系 |
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| 引用本文： | 钟福军,潘家永,巫建华,夏菲,伏顺成,祁家明,赵奇峰.粤北长江铀矿田辉长闪长岩的岩石成因及其与铀成矿的关系[J].地球科学,2019,44(9):3042-3059. |
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| 作者姓名： | 钟福军 潘家永 巫建华 夏菲 伏顺成 祁家明 赵奇峰 |
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| 作者单位： | 1.东华理工大学核资源与环境国家重点实验室, 江西南昌 330013 |
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| 基金项目： | 核资源与环境国家重点实验室自主基金项目Z1608国家自然科学基金项目U1403292江西省研究生创新项目YC2016-B074中国地质调查局项目12120115035601国家自然科学基金项目41772066“十二五”国家科技支撑计划项目2015BAB05B04 |
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| 摘 要： | 长江铀矿田深部赋矿辉长闪长岩的岩石成因制约着对铀成矿作用认识的深入.通过对辉长闪长岩开展锆石U-Pb定年、Lu-Hf同位素、矿物学和地球化学分析，探讨其岩石成因、成岩构造背景及其与铀成矿的关系.辉长闪长岩LA-ICP-MS锆石U-Pb年龄为150 Ma，形成于晚侏罗世，具板内玄武岩地球化学特征.环带斜长石与黑云母主量元素变化记录了岩浆由基性到中性的演化过程.锆石（~150 Ma）εHf（t）为-14.1~-8.6，tDM2为1.7~2.1 Ga.辉长闪长岩源区为遭受俯冲带流体交代改造的相对富集地幔，岩浆上升侵位过程与中元古代-古元古代壳源物质发生了不同程度的地壳混染，形成于地壳伸展拉张和岩石圈大规模减薄的构造背景.辉长闪长岩为铀成矿提供了更为有利的还原性环境，促使热液中U6+的还原沉淀.
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| 关 键 词： | 辉长闪长岩 岩石圈减薄 铀成矿作用 "交点"型铀矿 长江铀矿田 地质年代学 |
| 收稿时间： | 2017-06-05 |
Petrogenesis and Its Relationship with Uranium Mineralization of Gabbro-Diorite in Changjiang Uranium Ore-Field,Northern Guangdong Province,China |
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| Abstract: | Understanding for uranium mineralization was absolutely restricted by the petrogenesis of gabbro-diorite,which emplaced into the Yanshanian biotite granite at the deep part of Changjiang uranium ore-field. We provide LA-ICP-MS zircon UPb age,Lu-Hf isotopic,mineralogical and geochemical evidence to analyse the poetrogenesis,tectonic background and its relationship with uranium mineralization. Gabbro-diorite emplaced at the Late Jurassic (LA-ICP-MS zircon U-Pb isotopic age:150±1 Ma (n=17,MSWD=0.18)) and was geochemically characteristic of within-plate basalt. The magma evolution process (ranges from basic to neutral magma) has been effectively recorded by the transformation of major elements in zoned plagioclase and biotite from gabbro-diorite. The zircon εHf(t) values range from -14.1 to -8.6 and the two-stage model ages (tDM2) range from 1.7 Ga to 2.1 Ga. The magmatic source was the relatively enriched mantle changed by the metasomatism fluid originated from the subduction zone of Pacific Ocean Plate which started from the Middle Jurassic. Gabbro-diorite has undergone a variational degree crustal contamination with the Proterozoic-Palaoproterozoic crustal material in the process of emplacement during the Late Mesozoic large scale lithosphere thining tectonic background. Gabbro-diorite provides a better reductive environment than the granite for uranium mineralization,prompting U6+ been reduced to pitchblende in the ore forming hydrothermal fluid. |
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