| 福建古田县三保钨钼矿床地质地球化学 |
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| 引用本文：.1989.geology and geochemistry of the Sanbao Tungsten-Molybdenum ore deposit in Gutian county, Fujian province[J].Mineral Deposits,8(1):29~38 |
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| 中文摘要:三保钨钼矿床位于政和-大浦大断裂之东侧。矿体产于花岗斑岩(85 Ma)与侏罗系南园组流纹质晶屑凝灰熔岩的内、外接触带中，属中-高温石英脉型矿床。石英包裹体的δDH2O。值为-4l一-47‰，δ18OH2O值为-6.0一-7.3‰，表明成矿热液是来自大气降水。根据矿体中δ34S值和黑钨矿中富Nb2O3、贫Ta2O5，辉钼中Re及黄铁矿中Co高、Ni低等特征，证实成矿物质与同熔型花岗斑岩是同一来源的。花岗斑岩中除W、Mo含量较高外，Cr、Ba、Re的含量和∑Ce／∑Y比值、磁铁矿—榍石一锆石等副矿物组合都与华南过渡型地壳同熔型花岗岩系列成因相似。根据上述资料推测本矿床成矿模式是：同熔型花岗斑岩形成时初步富集了矿质→地下水循环热液与花岗斑岩作用淋滤出矿质→转移到构造有利部位沉淀形成矿体。 |
| 中文关键词:古田三保 微量元素 同位素 花岗斑岩 成矿模式 |
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| geology and geochemistry of the Sanbao Tungsten-Molybdenum ore deposit in Gutian county, Fujian province |
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| Abstract:The ore deposit in question lies within the Fujian-Zhejiang-Guangdong Cenozoic fault depression, on the east side of Zhenghe-Dapu fault. The orebodies occur in endo-and exo-contact zones between a granite porphyry(85Ma)and the rhyolitic crystal tufflava of Upper Jurassic Nanyuan Formation. The orebodies have the following characteristics: (1) δ18OH2O=-3.3一-11.7‰, andδDH2O-4l一-120‰, within the field of meteoric hydrothermal fluids) δ34S=1.89—9.88‰,δ34S∑S=4.9‰ at the endocontact zone and 3.8‰ at the exocontact zone respectively, suggesting a mixed crust-mantle sulfur source; (2) wolframite is rich in Nb2O5(0.12一1.81％)and poor in Ta2O5(0.0017一0.0024％), with low Ta2O5/Nb2O5 ratios(0.012—0.039); except for very few samples, the Re contents of molybdenite are mostly lower than 15 ppm; Co contents of pyrite are 24—153 ppm, and Ni<10ppm; (3)the ore-formig temperatures of wolframite and molybdenite are 270一297℃ and 240—265℃ respectively, showing gradually decreasing tendency from endo-contact zone to exocontact zone. The granite porphyry has four features: (1)SiO2>75％,(K2O+Na2O)>8.5％ and Na2O/K2O=0.77, Al2O3/(K2O+Na2O+CaO)(mol)=1.05; (2)it is of magnetite-orthite-sphene-zircon type granite with magnetite being dominant; (3)∑REE=174ppm, ∑Ce/∑Y=4.77 andδEu=0.51, with moderate Eu deficiency and asymmetric “V”-shaped distribution curve; (4)the intrusive body is rich in W, Mo, Sn, Be, Ba etc. and poor in Cu, Ni. The researches have led the author to the following conclusions: (1) The granite porphyry is genetically of transitional crustal syntectic type and also serves as the supplier of the ore materials; and (2) the infiltrating metasomatism of granite porphyry by meteoric-hydrothermal fluids leached out the ore materials which formed quartz vein type tungsten-molybdenite deposits at medium-high temperatures. |
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