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陈鑫,郑有业,许荣科,蔡鹏捷,林成贵,白杰,孙述海,鲁立辉. 2018. 柴北缘鱼卡榴辉岩型金红石矿床金红石矿物学、元素地球化学及成因. 岩石学报, 34(6): 1685-1703
柴北缘鱼卡榴辉岩型金红石矿床金红石矿物学、元素地球化学及成因
作者单位E-mail
陈鑫 中国地质大学(武汉)资源学院, 武汉 430074  
郑有业 中国地质大学(武汉)资源学院, 武汉 430074
中国地质大学(武汉)地质调查研究院, 武汉 430074
中国地质大学地质过程与矿产资源国家重点实验室, 北京 100083 
zhyouye@163.com 
许荣科 中国地质大学(武汉)地质调查研究院, 武汉 430074  
蔡鹏捷 中国地质大学(武汉)地质调查研究院, 武汉 430074  
林成贵 中国地质调查局发展研究中心, 北京 100037  
白杰 中国地质大学(武汉)资源学院, 武汉 430074  
孙述海 中国地质大学(武汉)资源学院, 武汉 430074  
鲁立辉 中国地质大学(武汉)资源学院, 武汉 430074  
基金项目:本文受长江学者和创新团队发展计划(IRT14R54)和地质调查项目(121201011000150004)联合资助.
摘要:
      鱼卡金红石矿床是青海省境内发现的第一个超大型榴辉岩型金红石矿床。笔者在总结前人基础资料及详细野外地质矿产调查的基础上,通过榴辉岩岩石学及金红石矿物学研究,利用LA-ICP-MS法对该矿床中的金红石进行原位微量元素分析等。结果表明:金红石赋存状态主要有五种,即包裹结构、粒间结构、串珠状结构、退变残余结构、丝缕状出溶结构,其中以粒间和串珠状赋存状态产出时,含矿性最好。同时,变质阶段的差异、流体活动的强弱将影响金红石的赋存状态。流体活动越弱时,野外表现为榴辉岩的新鲜程度越高、且少或不发育长英质脉体、矿物越自形,则越有利于形成粒间和串珠状金红石富矿;折返过程中流体或熔体作用过强、野外表现为广泛发育长英质脉体、榴辉岩中矿物呈他形产出时,则金红石已经退变为钛铁矿和榍石。总结前人的地球化学和年龄数据表明:富集地幔源区、演化程度高、陆壳混染程度低的富钛基性原岩是鱼卡榴辉岩型金红石矿床主要物质来源,高压(超高压)变质作用促进了钛的进一步富集成矿,成矿年代集中在440~430Ma。金红石锆温度计显示的成矿温度主要在570~671℃之间,金红石中高场强元素Ti、Nb、Ta、Zr、Hf等富集,表明其可能形成于俯冲带环境。这些成因认识等将为柴北缘成矿带榴辉岩型金红石矿床的进一步找矿工作部署、勘查评价及突破提供了重要的理论支撑与借鉴。
英文摘要:
      The Yuka rutile deposit, located in Qinghai Province, is the first super large eclogite-type rutile deposit from North Qaidam ultra-high pressure metamorphic (UHPM) belt. In this paper, based on the research of predecessors, field geological survey, petrography, mineralogy and trace elements of rutile were used to summarize the occurrence of rutile, metallogenic geological background and ore genesis. The results show that the rutiles occur as mineral inclusions, intergranular structure in garnet and omphacite, mineral aggregate intergrowth with quartz, ilmenite or titanite in rutile rim as residual structure and silk thread shaped exsolution structure in fluid and the ore grades are better when rutile occur as the intergranular and mineral aggregate structure. Meanwhile, the occurrences of rutile are influenced by different metamorphic episodes and intensity of melt and fluid activities. When fluid or melt activites are weak, outcrops of fresh eclogites with little felsic veins and minerals with idiomorphic structure are conducive to form high-grades ore. However, when melt or fluid activities are strong in a "hot" exhumation stage and the field is characterized by lots of leucosomes in eclogites. In this case, voluminous rutiles have degenerated into xenomorphic titanite and ilmenite. Based on previous geochemical and age data, the result shows that the Ti-rich mafic protoliths from fertile mantle source, with high degree of evolution and low contamination of the continental crust are the essential condition for formation of eclogite-type rutile deposits. The high-pressure (ultra-high pressure) metamorphism promotes the formation of rutile. The age of rutile formation is concentrated in 440~430Ma. Zr-in-rutile thermometry shows that the metallogenic temperatures range from 570 to 671℃. Enriched high field strength elements (Ti, Nb, Ta, Zr, Hf) in rutile indicate that they may be formed in the subduction zone environment. These understandings provide the reference and theoretical support to further works in finding eclogite-type rutile deposits, guiding the prospecting work and industrial using of rutile deposits in North Qaidam UHPM belt.
关键词:金红石矿床  榴辉岩  LA-ICP-MS微量元素分析  成矿物质来源  鱼卡  柴北缘
投稿时间:2017-02-03  修订日期:2018-04-23
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主办单位:中国矿物岩石地球化学学会
印刷版(Print): ISSN 1000-0569 网络版(Online): ISSN 2095-8927
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