| 胶东牟乳成矿带范家庄金矿床成矿流体特征及其地质意义 |
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| 引用本文： | 王勇军,刘颜,黄鑫,徐昌,沈立军,张业智,张兆民.胶东牟乳成矿带范家庄金矿床成矿流体特征及其地质意义[J].吉林大学学报(地球科学版),2020,50(4):1012-1028. |
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| 作者姓名： | 王勇军 刘颜 黄鑫 徐昌 沈立军 张业智 张兆民 |
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| 作者单位： | 1. 山东省煤田地质规划勘察研究院, 济南 250100;2. 中国地球物理学会煤田地球物理重点实验室, 济南 250100;3. 山东省煤田地质局第一勘探队, 山东 枣庄 277000;4. 中国地质大学(武汉)资源学院, 武汉 430074 |
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| 基金项目： | 国家重点研发计划项目（2016YFC0600105）；山东省煤田地质局科研专项基金项目（鲁煤地科字（2017）2号） |
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| 摘 要： | 牟乳成矿带是胶东半岛金矿集区三大金成矿带之一，但带内金矿床的成矿流体来源仍存在着较大分歧。范家庄金矿床是近年在该成矿带内新发现的金矿床，其成矿流体的研究较为薄弱。鉴于此，本文从流体包裹体和H-O同位素研究入手，结合矿床地质特征，对范家庄金矿床的成矿流体和矿床成因进行探讨。金矿体主要产于侏罗纪弱片麻状黑云母二长花岗岩内，呈脉状、透镜状，受断裂构造控制明显。该矿床热液成矿期可分为3个成矿阶段：石英-粗粒黄铁矿阶段（成矿早阶段）、石英-金-多金属硫化物阶段（主成矿阶段）、石英-碳酸盐阶段（成矿晚阶段）。流体包裹体岩相学特征显示，矿床中的原生包裹体以气液两相包裹体和纯液相水溶液包裹体为主，另有少量含CO2三相包裹体。显微测温结果显示，成矿早阶段和主成矿阶段的均一温度分别为167.2~297.5℃和168.4~253.6℃，盐度（w（NaCl））分别为3.55%~22.65%和2.58%~12.05%，密度分别为0.77~1.06 g/cm3和0.84~1.02 g/cm3，具有中低温、中低盐度、低密度的特征，与中温热液成矿系统流体特征相一致。对成矿压力和深度的估算表明，主成矿阶段的成矿压力为45.8~68.7 MPa （平均为52.8 MPa），成矿深度为5.38~6.71 km （平均为5.93 km），显示出中浅成成矿的特点。成矿流体H-O同位素示踪显示，成矿早阶段流体的δDH2O-SMOW值介于-96.9‰~-89.0‰之间，δ18OH2O-SMOW值介于-4.3‰~4.5‰之间；主成矿阶段的δDH2O-SMOW值介于-90.7‰~-85.3‰之间，δ18OH2O-SMOW值介于-5.4‰~-0.2‰之间。由此认为，范家庄金矿床的成矿流体来源于岩浆水与大气降水的混合，且随着成矿流体的演化，大气降水的混入比例增加。综合矿床地质特征和成矿流体研究，认为范家庄金矿床应属中温热液脉型金矿床。
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| 关 键 词： | 流体包裹体 H-O同位素 中温热液脉型金矿 范家庄金矿床 牟乳成矿带 |
| 收稿时间： | 2018-12-21 |
Characteristics of Ore-Forming Fluids and Geological Significance of Fanjiazhuang Gold Deposit in Muping-Rushan Metallogenic Belt,Jiaodong Peninsula |
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| Wang Yongjun,Liu Yan,Huang Xin,Xu Chang,Shen Lijun,Zhang Yezhi,Zhang Zhaomin.Characteristics of Ore-Forming Fluids and Geological Significance of Fanjiazhuang Gold Deposit in Muping-Rushan Metallogenic Belt,Jiaodong Peninsula[J].Journal of Jilin Unviersity:Earth Science Edition,2020,50(4):1012-1028. |
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| Authors: | Wang Yongjun Liu Yan Huang Xin Xu Chang Shen Lijun Zhang Yezhi Zhang Zhaomin |
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| Institution: | 1. Shandong Provincial Research Institute of Coal Geology Planning and Exploration, Jinan 250100, China;2. Key Laboratory of Coalfield Geophysics, Geophysical Society of China, Jinan 250100, China;3. The First Prospecting Team of Shandong Coal Geology Bureau, Zaozhuang 277000, Shandong, China;4. School of Earth Resources, China University of Geosciences(Wuhan), Wuhan 430074, China |
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| Abstract: | The Muping-Rushan metallogenic belt is one of the three major gold metallogenic belts in the world-class Jiaodong gold province. However, its sources of ore-forming fluids is still hotly debated. The Fanjiazhuang deposit is a newly discovered gold deposit in this belt, and the study of its ore-forming fluid is relatively weak. Combined with the geological characteristics of the deposit, the fluid inclusions,hydrogen, and oxygen isotopic geochemistry were analyzed to understand the characteristics, origin, and evolution of the ore-forming fluids. The gold orebodies are mainly existed in Jurassic granites, in vein and lens shape, and are controlled obviously by fault structures. The hydrothermal mineralization of Fanjiazhuang deposit can be divided into 3 stages: Quartz-coarse pyrite (early metallogenic stage), quartz-Au polymetallic sulfide (major metallogenic stage), and quartz-carbonate (late metallogenic stage). The petrographic observation indicates that there are mainly two-phase aqueous and mono-phase liquid aqueous inclusions, with a few three-phase CO2-bearing inclusions. The micro-thermometry shows that the homogeneous temperature of the fluid inclusions in the early and major metallogenic stages is 167.2-297.5 ℃ and 168.4-253.6 ℃, salinity is 3.55%-22.65% and 2.58%-12.05%, and density is 0.77-1.06 g/cm3 and 0.84-1.02 g/cm3, respectively. All these features indicate the characteristics of middle-low temperature, middle-low salinity, and low density, a typical mesothermal gold deposit. The ore-forming pressure in the major metallogenic stage is estimated to be 45.8-68.7 MPa (average 52.8 MPa), and the corresponding ore-forming depth is 5.38-6.71 km (average 5.93 km), medium-shallow mineralization. The hydrogen and oxygen isotopic compositions of the ore-forming fluids show the δDH2O-SMOW value from -96.9‰ to -89.0‰ and the δ18OH2O-SMOW value from -4.3‰ to 4.5‰ in the early stage. The δDH2O-SMOW and δ18OH2O-SMOW values in the major metallogenic stage change from -90.7‰ to -85.3‰ and from -5.4‰ to -0.2‰, respectively. All these above suggest that the ore-forming fluid of Fanjiazhuang gold deposit was derived from the mixture of magmatic water and meteoric water, and the proportion of the latter increased with the evolution of the ore-forming fluid. Based on the geological and fluid inclusion features, Fanjiazhuang deposit should be a mesothermal gold deposit. |
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| Keywords: | fluid inclusions hydrogen and oxygen isotopes mesothermal gold deposit Fanjiazhuang gold deposit Muping-Rushan metallogenic belt |
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