福建行洛坑钨矿床黑钨矿LA-ICP-MS U-Pb年龄和微量元素地球化学特征  

In-situ LA-ICP-MS U-Pb Dating and Trace Element Analyses of Wolframites from the Xingluokeng Tungsten Deposit in Fujian Province, China

作　　者：张清清 高剑峰[1] 唐燕文[1] 闵康 ZHANG Qing-qing;GAO Jian-feng;TANG Yan-wen;MIN Kang(State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院地球化学研究所,矿床地球化学国家重点实验室,贵阳550081 [2]中国科学院大学,北京100049

出　　处：《矿物岩石地球化学通报》2020年第6期1278-1291,1311,共15页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家重点研发计划项目(2016YFC0600207)。

摘　　要：为精确厘定福建行洛坑钨矿床成矿时代和揭示其成矿流体演化特征,利用LA-ICP-MS对矿床中的浸染状石英细脉和大脉中的黑钨矿进行了U-Pb年代学和微量元素地球化学研究。结果表明,石英细脉和大脉中黑钨矿的原位U-Pb年龄分别为(151.3±5.8)Ma和(150.5±8.1)Ma。钨成矿时代与南岭地区钨矿化幕次相吻合,表明华南晚侏罗世大规模钨成矿作用可能从南岭地区向东延伸至武夷山成矿带。细脉黑钨矿较大脉黑钨矿具有更低的δEu值,但Nb、Ta含量更高,暗示早期的浸染状石英细脉形成于相对还原环境,晚期可能由于大气降水的增加使氧逸度升高。此外,黑钨矿Y/Ho、Zr/Hf值的非CHARAC行为及其稀土模式四分组效应暗示钨成矿过程中氟对钨等元素的迁移、富集起着重要作用。黑钨矿稀土总量和稀土配分曲线与南岭地区石英脉型钨矿相似,均为重稀土富集型。研究表明行洛坑钨矿属于石英脉型钨矿而非以往认为的斑岩型钨矿。In situ LA-ICP-MS U-Pb dating and trace element analyses of the wolframites disseminated in quartz veinlets and coarse quartz veins of ores in the Xingluokeng tungsten deposit in Fujian were carried out. The U-Pb dating results show the ages of wolframite samples from quartz veinlets and coarse veins are(151.3±5.8) Ma and(150.5±8.1) Ma, respectively. The timing of tungsten mineralization of the deposit is coincided with the episodes of tungsten mineralization in the Nanling area, indicating that the large-scale tungsten mineralization at late Jurassic in South China could be eastward extended from the Nanling area to the Wuyishan metallogenic belt. Wolframites from quartz veinlets have higher Nb and Ta concentrations, and lower δEu values than those from coarse quartz veins of ores, suggesting that the early stage quartz veinlets with disseminated wolframites were formed under the relatively reductive condition, whereas the late stage mineralization could be formed in a relatively oxidized ore-forming fluid due to the increase of oxygen fugacity which could be attributed to the addition of meteoric water. In addition, the non-CHARAC features of Y/Ho and Zr/Hf ratios and unusual tetrad effect of REE patterns of the wolframites suggest that the F may have played an important role in the migration and enrichment of tungsten. The REE contents and HREE-enriched characteristic patterns of wolframites are similar to those of wolframites in the quartz vein-type tungsten deposits in the Nanling area, indicating that the Xingluokeng deposit belongs to the vein-type tungsten deposit rather than the previously believed porphyry tungsten deposit.

关 键 词：行洛坑钨矿床 黑钨矿 U-PB定年 武夷山成矿带 地球化学 

分 类 号：P595[天文地球—地球化学] P618.67[天文地球—地质学]