ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    浙江缙云县吾山萤石矿床成因:来自稀土元素、流体包裹体、红外光谱的制约

    Genesis of Wushan Fluorite Deposit in Jinyun County, Zhejiang Province: Constraints from Fluorite Rare Earth Elements, Fluid Inclusions and Infrared Spectroscopy

    • 摘要: 吾山萤石矿床位于华夏板块北东端,浙江萤石矿集区中部。矿床产于下白垩统馆头组与燕山晚期花岗岩接触带中,矿体受NW向断裂控制,发育条带状萤石。在野外地质调查的基础上,对不同颜色萤石的稀土元素、流体包裹体及红外光谱开展研究。研究结果表明,不同颜色萤石的稀土元素含量、成矿温度呈现规律性的变化。从绿色萤石到紫色萤石再到黄色萤石,具有δEu值增大,∑REE值减小,LREE/HREE值增大,成矿温度逐渐降低的特征。结合矿床地质特征,认为3种颜色萤石结晶成矿过程为温度变化范围较大的还原环境,萤石形成顺序为绿色萤石先结晶,紫色萤石次之,黄色萤石最后形成。Tb/Ca-Tb/La、La/Ho-Y/Ho图解和包裹体测温显示,区内不同颜色萤石为同一流体来源在同一成矿期次不同阶段成矿。条带状萤石的形成是成矿热液周期性脉动上涌的结果。研究区萤石矿床的成矿流体属于中–低温、低盐度、低密度含F热液,吾山萤石矿床属于中–低温热液裂隙填充型萤石矿床。

       

      Abstract: The Wushan fluorite deposit is located at the northeast end of the Cathaysia Block, in the central part of the fluorite mining area in Zhejiang Province. The deposit is located in the contact zone between the Guantou Formation of the Cretaceous and the Yanshan granite. The distribution of the ore body is controlled by northwest trending faults, and banded fluorite is developed. Based on geological surveys, research was conducted on rare earth elements, fluid inclusions, and infrared spectra of fluorite with different colors. The research results indicate that the rare earth element content and mineralization temperature of fluorite with different colors shows regular changes. From green fluorite to purple fluorite and then to yellow fluorite, δEu increases, the ∑REE decreases, the LREE/HREE ratio increases and mineralization temperature decrease. Based on the geological characteristics of the deposit, this study suggests that the crystallization and mineralization process of the three colors of fluorite is a reducing environment with a large temperature range. The formation sequence of fluorite is that green fluorite is formed first, followed by purple fluorite, and yellow fluorite is formed latest. The Tb/Ca-Tb/La and La/Ho-Y/Ho diagrams and inclusion temperature measurements show that different colored fluorites in the area are formed from the same fluid source at different stages of the same mineralization period. The formation of banded fluorite is the result of periodic pulsation and upwelling of ore-forming hydrothermal fluids. Overall, the ore-forming fluid of the fluorite deposit in the study area belongs to medium low temperature, low salinity, and low-density F-containing hydrothermal fluids. In summary, the Wushan fluorite deposit belongs to the medium to low temperature hydrothermal fissure filling type fluorite deposit

       

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