赣南盘古山和淘锡坑黑钨矿化学成分和晶体结构及指示意义

发布时间：2018-05-03 02:43

本文选题：黑钨矿 + 化学成分　；参考：《地质学报》2017年04期

【摘要】：赣南地区是世界著名的钨矿资源产区,黑钨矿是该区钨矿中最重要的钨矿石矿物。本文以赣南盘古山和淘锡坑两个典型钨矿床中的黑钨矿作为研究对象,采用电子探针、X射线衍射等分析技术对黑钨矿的晶体结构、化学成分及其空间分布规律开展研究。结果表明,研究区黑钨矿主要属于锰钨铁矿,黑钨矿中Mn~(2+)和Fe~(2+)为类质同象的关系,因此MnO与FeO之间呈明显的负相关。在空间上x(Fe/(Mn+Fe))值有一定的变化规律,由矿脉深部到浅部,x值先变大再变小,反映出矿液的运移从下而上,随后上部矿液又有向下回流的现象;同一脉体各中段均为中间x(Fe/(Mn+Fe))值大,向两侧比值减小,说明同一中段上矿体中部黑钨矿形成温度较高,两侧黑钨矿形成温度较低。盘古山黑钨矿中Nb和Ta的含量均高于淘锡坑黑钨矿,这说明盘古山黑钨矿体比淘锡坑黑钨矿更靠近岩体。单一矿脉自下而上黑钨矿中Nb、Ta含量先是迅速变小,而后略有增大,这也说明矿液运移的复杂性。两矿区黑钨矿都具有重稀土富集左倾的"躺椅式"球粒陨石标准化配分模式。盘古山矿床黑钨矿稀土总量(ΣREEs)较高,La_N/Yb_N比值较低,轻重稀土分馏较为明显;淘锡坑矿床黑钨矿稀土总量(ΣREEs)较低,La_N/Yb_N比值范围较广,轻重稀土分馏程度有强有弱。它们都具有强烈的δEu负异常和弱的δCe负异常,说明矿床是在封闭的还原条件下形成的。将赣南盘古山、淘锡坑钨矿与广西珊瑚、江西浒坑和湖南瑶岗仙钨矿中黑钨矿的晶胞参数进行对比分析,显示产于花岗岩体内接触带的黑钨矿FeO含量较低,晶胞参数值较大;产于花岗岩体外接触带的黑钨矿FeO含量较高,晶胞参数值较小。因此,利用黑钨矿的化学成分和晶体结构的变化特征,可以指示成矿物质在空间上的运移特征,也可作为判断矿床成因的依据。研究成果对同类矿床的研究具有借鉴和启示意义。
[Abstract]:Gannan area is a world famous tungsten ore resource producing area, wolframite is the most important tungsten ore mineral in this area. In this paper, wolframite from two typical tungsten deposits, Pangushan and Taoxinkeng, in south Jiangxi Province, is taken as the research object. The crystal structure, chemical composition and spatial distribution of wolframite are studied by means of electron probe X-ray diffraction and other techniques. The results show that wolframite mainly belongs to manganite, and Mn~(2) and Fe~(2 (in wolframite) are similar to each other, so there is an obvious negative correlation between MnO and FeO. In space, the value of x(Fe/(Mn Fe ~ (2 +) is changed to a certain extent, from the deep to the shallow part of the vein, the value of x(Fe/(Mn _ (x) increases first and then becomes smaller, which reflects the movement of the ore fluid from the bottom to the top, and then the downward return of the upper ore fluid. Each middle part of the same vein body has a large value of intermediate x(Fe/(Mn Fe ~ (2 +), and the ratio to both sides decreases, which indicates that the formation temperature of wolframite in the middle part of the same middle segment is higher than that in the two sides of the body, and the formation temperature of wolframite on both sides is relatively low. The contents of NB and Ta in Pangoshan wolframite are higher than those in Taoxikeng wolframite, which indicates that the Pangoshan wolframite body is closer to the rock mass than the Taoxikeng wolframite. The content of NB ~ (2 +) Ta in wolframite decreases rapidly and then increases slightly from the bottom to the top of the single vein, which indicates the complexity of ore migration. Both wolframite and wolframite have a "deck chair" chondrite standardized distribution model with heavy rare earth enrichment. The 危 REEsS of wolframite in Pangushan deposit is relatively high, the ratio of La-She / Yb-SHAN is lower and the fractionation of heavy and heavy rare earths is obvious, and the 危 REEsof the wolframite is lower in the Pangushan deposit, and the ratio of La-She / YbN is relatively wide and the fractionation of heavy and heavy rare earth is strong and weak. Both of them have strong 未 EU negative anomalies and weak 未 ce negative anomalies, indicating that the deposits were formed under closed reduction conditions. The unit cell parameters of wolframite in Pangushan, Taoxikeng tungsten mine, Guangxi coral, Huokeng and Yaogangxian tungsten deposits in Hunan province are compared and analyzed. The results show that the FeO content of wolframite occurring in the contact zone of granite is lower and the unit cell parameter value is larger. Wolframite, which occurs in the contact zone of granite in vitro, has higher FeO content and smaller unit cell parameter. Therefore, the change of chemical composition and crystal structure of wolframite can indicate the migration characteristics of ore-forming materials in space, and it can also be used as the basis for judging the genesis of the deposit. The research results can be used for reference and enlightenments in the study of similar deposits.
【作者单位】：长安大学地球科学与资源学院西部矿产资源与地质工程教育部重点实验室;中国地质科学院矿产资源研究所;江西地矿局赣南地质调查大队;
【基金】：国土资源部公益性行业科研专项(201411050) 国家重点研发计划课题(2016YFC0600208) 国家自然科学基金重点资助计划(41430314) 中国矿产地质与区域成矿规律综合研究(中国矿产地质志)(编号:1212011220369)资助的成果
【分类号】：P618.67

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