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0.77~1.06g/cm3和0.84~1.02g/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45.8~68.7MPa(平均为52.8MPa),成矿深度为5.38~6.71km(平均为5.93km),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,δ18 OH 2O-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,δ18 OH 2O-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。
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 3stages: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 0.77-1.06g/cm3 and 0.84-1.02g/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 45.8-68.7MPa(average 52.8MPa),and the corresponding ore-forming depth is 5.38-6.71km(average 5.93 km),medium-shallow mineralization.The hydrogen and oxygen isotopic compositions of the oreforming fluids show theδDH 2O-SMOWvalue from-96.9‰to-89.0‰and theδ18 OH 2O-SMOWvalue from-4.3‰to 4.5‰in the early stage.TheδDH 2O-SMOWandδ18 OH 2O-SMOWvalues 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 t
作者
王勇军
刘颜
黄鑫
徐昌
沈立军
张业智
张兆民
Wang Yongjun;Liu Yan;Huang Xin;Xu Chang;Shen Lijun;Zhang Yezhi;Zhang Zhaomin(Shandong Provincial Research Institute of Coal Geology Planning and Exploration,Jinan 250100,China;Key Laboratory of Coalfield Geophysics,Geophysical Society of China,Jinan 250100,China;The First Prospecting Team of Shandong Coal Geology Bureau,Zaozhuang277000,Shandong,China;School of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074,China)
出处
《吉林大学学报（地球科学版）》
EI
CAS
CSCD
北大核心
2020年第4期1012-1028,共17页
Journal of Jilin University：Earth Science Edition
基金
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)。
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
fluid inclusions
hydrogen and oxygen isotopes
mesothermal gold deposit
Fanjiazhuang gold deposit
Muping-Rushan metallogenic belt
