| 甘肃龙首山成矿带新水井铀(钍)矿床元素迁移规律及成矿作用过程研究 |
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| 引用本文： | 钟军,范洪海,顾大钊,王生云,陈金勇,史长昊,李恒强.甘肃龙首山成矿带新水井铀(钍)矿床元素迁移规律及成矿作用过程研究[J].中国地质,2016(4):1393-1408. |
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| 作者姓名： | 钟军 范洪海 顾大钊 王生云 陈金勇 史长昊 李恒强 |
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| 作者单位： | 核工业北京地质研究院, 北京 100029,核工业北京地质研究院, 北京 100029,核工业北京地质研究院, 北京 100029,核工业北京地质研究院, 北京 100029,核工业北京地质研究院, 北京 100029,中国地质大学(北京)地球科学与资源学院, 北京 100083,核工业北京地质研究院, 北京 100029 |
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| 基金项目： | 中国地质调查局地质调查项目（12120114015201），核工业地质局项目（D163）和国家自然科学基金（41502083）联合资助。 |
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| 摘 要： | 新水井铀(钍)矿床位于甘肃省龙首山成矿带,是碱交代型铀矿床的典型代表,其矿体完全产于钠交代蚀变花岗岩中,成矿过程可划分为钠交代蚀变、铀钍矿化和成矿后3个主要阶段。文章对该矿床花岗岩原岩、蚀变岩及矿石开展了系统主微量元素分析,采用Grant等浓度线法探讨了钠交代蚀变和铀钍矿化阶段的元素迁移规律,结果表明:钠交代蚀变阶段为富含Na、Ca、过渡族元素(Sc、V、Cr、Co、Ni)、U、Th及CO2、H2O等挥发分的复杂流体,钠交代过程中原岩中的大离子亲石元素(Rb、Ba)和部分轻稀土元素(LREE)不同程度带出;而铀钍成矿阶段成矿流体则富集重稀土元素(HREE)、U、Th、PO43-等成分,CO2等挥发分大量逸出。结合前人研究,认为新水井矿床成矿流体可能来自地幔流体和大气降水热液的混合;等挥发分CO2的逸出是新水井矿床最重要的矿质沉淀机制,导致了铀钍矿物和磷酸盐矿物(磷灰石)的共沉淀,而磷灰石的沉淀又促进了以磷酸盐形式搬运的Th元素的沉淀。
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| 关 键 词： | 龙首山成矿带 新水井铀(钍)矿床 地球化学 元素迁移 成矿流体 成矿机制 |
| 收稿时间： | 2016/2/14 0:00:00 |
| 修稿时间： | 3/4/2016 12:00:00 AM |
Major and trace element migration and metallogenic processes of the Xinshuijing U-Th deposit in the Longshoushan metallogenic belt, Gansu Province |
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| ZHONG Jun,FAN Hong-hai,GU Da-zhao,WANG Sheng-yun,CHEN Jin-yong,SHI Chang-hao and LI Heng-qiang.Major and trace element migration and metallogenic processes of the Xinshuijing U-Th deposit in the Longshoushan metallogenic belt, Gansu Province[J].Chinese Geology,2016(4):1393-1408. |
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| Authors: | ZHONG Jun FAN Hong-hai GU Da-zhao WANG Sheng-yun CHEN Jin-yong SHI Chang-hao and LI Heng-qiang |
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| Institution: | Beijing Research Institute of Uranium Geology, Beijing 100029, China,Beijing Research Institute of Uranium Geology, Beijing 100029, China,Beijing Research Institute of Uranium Geology, Beijing 100029, China,Beijing Research Institute of Uranium Geology, Beijing 100029, China,Beijing Research Institute of Uranium Geology, Beijing 100029, China,School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China and Beijing Research Institute of Uranium Geology, Beijing 100029, China |
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| Abstract: | The Xinshuijing U-Th deposit in the Longshoushan metallogenic belt of Gansu Province is a typical alkali metasomatic U-Th deposit hosted in albitite. The ore-forming processes can be divided into three major mineralization stages, i.e., Nametasomatism, U-Th mineralization and post-ore stage. In this paper, the authors systematically analyzed major and trace elements in less-altered granite, albitite and ore of the Xinshuijing deposit, and discussed the element transportation using the isocon diagram proposed by Grant. During the Na-metasomatism stage, Na, Ca, Sc, V, Cr, Co, Ni, U, Th and CO2, H2O were enriched, while large ion lithophile elements and some of the light rare earth elements were depleted. The ore-forming fluids of the U-Th mineralization stage were rich in heavy rare earth elements, U, Th, PO43-, with volatile components (CO2, H2O, F, etc) abundantly escaped. Combined with former studies, the authors hold that the ore-forming fluid was the mixture between the mantle fluid and meteoric water. Vapor escape and the oxygen fugacity decrease seem to have been the major mineralization mechanism, which induced coprecipitation of U-Th minerals and apatite. Th transported in the form of compound phosphate was further precipitated after apatite formation. |
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| Keywords: | Longshoushan metallogenic belt Xinshuijing U-Th deposit geochemistry element transportation ore-forming fluid mineralization mechanism |
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