| 闽北羊角尾萤石矿成因:来自稀土、微量元素地球化学的证据 |
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| 引用本文：金松,王春连,高立湧,张成信,王占兵,王畅,孟都,商朋强.2022.闽北羊角尾萤石矿成因:来自稀土、微量元素地球化学的证据[J].地球学报,43(3):371-382. |
| DOI：10.3975/cagsb.2022.031401 |
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| 基金项目:中国地质调查局地质调查项目(编号: DD20190816; DD20190606);中化地质矿山总局化工地质科技项目(编号: ZHDK202004);中央级公益性科研院所基本科研业务费专项(编号: KK2005) |
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| 中文摘要:闽北浦城羊角尾萤石矿产于侏罗系梨山组火山碎屑岩中的断裂破碎带内, 对其地质矿产特征和矿石、围岩及矿区内黑云母正长花岗岩的岩石地球化学特征进行了研究。羊角尾萤石矿矿石∑REE为65.17×10–6～125.87×10–6, 重稀土相对富集, δEu和δCe无明显异常; Ni、Cd、Pb和As等中低温微量元素相对地壳富集。围岩梨山组火山碎屑岩轻重稀土分馏不明显, Eu负异常明显, Sm/Nd值与萤石接近, 微量元素相对地壳的含量曲线趋势与萤石基本一致。黑云母正长花岗岩则显示轻稀土富集、重稀土亏损, Eu正异常和Ce负异常的特征, Sm/Nd值远小于萤石矿。结合稀土微量元素特征及矿床成因判别图解, 认为羊角尾萤石矿的主要成矿物质来源为梨山组火山碎屑岩。成矿流体在形成后经历了长期的演化, 在此过程中与围岩发生了充分的水岩反映, 使Ca、F、REE等重新活化, 最终在构造破碎带就位沉淀形成矿体, 矿床成因类型为中-低温热液充填型。羊角尾萤石矿的矿床成因研究表明晚侏罗世火山-沉积岩系是区域萤石矿成矿的重要物源基础, 在区域找矿工作中应重点关注。 |
| 中文关键词:萤石矿 稀土元素 地球化学 成矿作用 羊角尾 |
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| Evidence from REE and Trace Element Geochemistry for Genesis of Yangjiaowei Fluorite Deposit in Northern Fujian |
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| Abstract:The Yangjiaowei fluorite deposit occurs in the fracture zone of the Jurassic Lishan Formation pyroclastic rocks in Pucheng, northern Fujian. In this study, the geological and mineral characteristics and the rock geochemistry characteristics of the ores, wall rocks, and biotite granites in the mining area are investigated. The ∑REE of fluorite ore is in the range of 65.17×10–6~125.87×10–6; HREE is relatively enriched; δEu and δCe are not obviously abnormal, and Ni, Cd, Pb, and As are relatively enriched in crustal micronutrients. The fractionation of LREE and HREE in the pyroclastic rocks of the Lishan Formation in the wall rock is not obvious; the negative Eu anomaly is obvious; Sm/Nd ratio is close to that of fluorite, and the curve of the crustal micronutrient content is largely consistent with that of fluorite. The biotite granite shows LREE enrichment, HREE depletion, positive Eu anomaly, and negative Ce anomaly, and the Sm/Nd ratio is much less than that of fluorite. According to the characteristics of REEs and micronutrients and the diagrammatic interpretation of the deposit genesis, the main source of ore-forming materials of the Yangjiaowei fluorite ore are likely the Lishan Formation pyroclastic rocks, which are not obviously related to the Late Jurassic syenite granites. The ore-forming fluid underwent a long-term evolution after its formation. In this process, the fluid and the surrounding rock had fully reflected, Ca, F, and REE were reactivated, and the ore bodies were deposited in the structural fracture zone, therefore, implying that the Yangjiaowei fluorite deposit is a mesothermal–epithermal filling deposit. The study of the ore-forming material source of the Yangjiaowei fluorite deposit indicates that the Late Jurassic volcanic-sedimentary rock series is an important material source of the regional fluorite mineralization and is worth considering in mineral explorations. |
| keywords:fluorite deposit REE geochemistry mineralization Yangjiaowei |
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