投稿时间：2024-06-26
修订日期：2025-04-27
网络发布日期：2025-07-01
中文摘要:福建漳平凤山矽卡岩型萤石矿床位于闽西南晚古生代坳陷东缘，其规模达到大型，是近年来闽西南非金属找矿勘查取得的重要成果之一。为揭示凤山萤石矿床的成因机制及其与区域岩浆活动的关系，文章在矿物结构研究的基础上，利用电子探针(EMPA)和LA-ICP-MS微区分析技术，对矿床中的石榴子石开展了主、微量成分和年代学测试。研究结果表明，凤山石榴子石具有早(Grt Ⅰ)和晚(Grt Ⅱ)2个世代，整体属于钙铁榴石-钙铝榴石固溶体系列(And7.00~100Gro0~93.00Spa0.44~42.62)。其中，GrtⅠ以钙铁榴石端员组分(And89.56Gro10.39Spa1.77)为主，亏损高场强元素(Nb、Zr、Hf、Ta、Th、Ti等)，呈现右倾型稀土元素配分模式、具有Eu正异常；而Grt Ⅱ以钙铝榴石端员组分(And11.69Gro88.28Spa24.36)为主，富集高场强元素，呈现左倾“M”型稀土元素配分模式、显示Eu负异常。此外，GrtⅠ显著富集微量元素W(249×10-6~950×10-6)、Sn(448×10-6~1699×10-6)，结合矽卡岩石中发现零星白钨矿的现象，暗示区内可能具有钨矿化的潜力。石榴子石的成分与结构特征暗示，其形成从一个相对开放、水岩比值较高的状态变为相对封闭、水岩比值较低的环境；且成矿流体由相对较高氧逸度、弱酸性特征逐渐向氧逸度降低、酸性减弱转变。文章首次采用石榴子石U-Pb年代学限定了凤山的萤石矿化年龄为(161.5±3.3)Ma，与矿区内的岩浆岩年龄((158.8±1.8)Ma)在误差范围内一致，表明其是岩浆热液的产物。结合区域动力学构造背景，笔者认为凤山萤石矿床的形成与燕山期构造域体制转换引起的岩浆热液活动关系密切，在富氟的岩浆热液、碳酸盐岩和接触带-层间断裂联合控制下形成了矽卡岩型萤石矿床。
Abstract:The Fengshan skarn fluorite deposit is located at the eastern margin of the Late Paleozoic depression basin in southwest Fujian Province. The discovery of this large-scale fluorite deposit is one of the important achievements of non-metallic prospecting projects in southwest Fujian Province in recent years. The results show that the Fengshan garnet has two generations (GrtⅠand Grt Ⅱ) and belongs to the andradite-grossular solid solution series (And7.00~100Gro0~93.00Spa0.44~42.62). The component of GrtⅠ is close to the andradite endmember (And89.56Gro10.39Spa1.77), with depletion of high field strength elements (Nb, Zr, Hf, Ta, Th, Ti, etc.) and a right-dipping rare earth element pattern with a positive Eu anomaly, whereas the component of GrtⅡ is close to the grossular endmember (And11.69Gro88.28Spa24.36) and displays enrichment of high field strength elements and a left-dipping "M"-type rare earth element pattern, with a negative Eu anomaly. The GrtⅠ is also significantly enriched in trace elements such as W (249×10-6~950×10-6) and Sn (448×10-6~1699×10-6), which suggests a potential for W mineralization. This is further supported by the presence of minor scheelite in skarn ores. Garnet texture and composition features indicate that the formation condition of garnet has changed from a relatively open system with a high water-rock ratio to a relatively closed environment with a low water-rock ratio, and the ore-forming fluids gradually changed from relatively high oxygen fugacity and weak acidity in the early stage to a neutral hydrothermal fluid with low oxygen fugacity in the late stage. The garnet U-Pb geochronology result shows that skarn fluorite mineralization age of the Fengshan deposit is (161.5±3.3) Ma, which belongs to the Late Jurassic and is consistent with the age of the magmatic rocks ((158.8±1.8)Ma) in the deposit within the limits of error. This study demonstrates that the Fengshan fluorite deposit is closely related to the magmatic-hydrothermal fluid caused by the tectonic transformation during the Yanshanian. The skarn fluorite mineralization was formed by combined controls which include F-rich magmatic-hydrothermal fluid, carbonate rocks, and contact zone-interlayer fractures.
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基金项目:本文得到福建省自然资源科技创新项目(编号:KY-060000-04-2023-004)和福建省教育厅中青年教师教育项目(编号:JAT210043)联合资助
引用文本：
陈素余,徐净,戴定贤,范育敏,郭新强.2025.福建漳平凤山矽卡岩型萤石矿床石榴子石特征及其意义[J].矿床地质,44(3):635~657CHEN SuYu,XU Jing,DAI DingXian,FAN YuMin,GUO XinQiang.2025.Characteristics and significance of garnet from Fengshan skarn fluorite deposit, Zhangping, Fujian Province[J].Mineral Deposits44(3):635~657
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