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• 岩石·矿床·地球化学 • 上一篇    下一篇

胶东夏甸金矿成矿流体及成矿物质来源:H-O、He-Ar、Sr-Nd-Pb同位素证据

杜佛光,姜耀辉,青龙,倪春雨   

  • 出版日期:2019-10-20 发布日期:2019-11-06

H-O, He-Ar and Sr-Nd-Pb Isotopic Constraints on the Sources of Ore-Forming Fluids and Ore-Forming Materials in the Xiadian Gold Deposit, Jiaodong

DU Foguang,JIANG Yaohui,QING Long,NI Chunyu   

  • Online:2019-10-20 Published:2019-11-06

摘要: 夏甸金矿是胶东金矿集区中一处大型焦家式矿床。文章在详尽的岩相学和矿相学研究基础上,对该矿床进一步开展
了H-O同位素并首次开展了He-Ar和Sr-Nd-Pb同位素示踪研究,为该矿床成矿流体及成矿物质来源提供了新的制约。石
英中流体包裹体的H-O同位素(δDV-SMOW=-102.3‰~-93.9‰,δ18OH2O=-0.2‰~1.6‰) 揭示出成矿流体主要为富集地幔流体,
并有少许大气降水加入;黄铁矿中He-Ar同位素[3He/4/He=0.58×10− 6~1.90×10− 6 (0.42~1.36 Ra),40Ar/36Ar=724.7~1358.4]同样
表明成矿流体以富集地幔流体为主导;矿石及蚀变岩的Nd-Pb同位素既不同于围岩花岗岩,也不同于基底变质岩,与胶东
地区中生代软流圈地幔起源的玄武岩也相差甚远,而与胶东地区中生代富集岩石圈地幔起源的煌斑岩相一致,但它们的初
始87Sr/86Sr比值明显高于煌斑岩,甚至高于围岩花岗岩。Sr-Nd-Pb同位素特征表明成矿流体及成矿物质来源于富集岩石圈地
幔,并在其上升过程中与基底变质岩发生了相互作用。

关键词: 夏甸金矿, H-O同位素, He-Ar同位素, Sr-Nd-Pb同位素, 成矿流体, 成矿物质

Abstract: The Xiadian gold deposit is a large Jiaojia-type gold deposit in Jiaodong district. On the basis of detailed petrographic and
mineralogical studies, we carried out the H-O isotopes and the first He-Ar and Sr-Nd-Pb isotope tracing studies of the Xiadian gold
deposit, which furnish the new constrains on the source of ore-forming fluids and materials. H-O isotopes of fluid inclusions in quartz
(δDV-SMOW=-102.3‰~-93.9‰ ,δ18OH2O=-0.2‰~1.6‰)reveal that the ore-forming fluids is mainly composed of enriched mantlederivedfluidwithinvolvedalittlemeteoricwater.
He-Arisotopeofpyrite[3He/4/He=0.58×10−6~1.90×10−6(0.42~1.36Ra),40Ar/36Ar=724.7~
1358.4] also indicates that the ore-forming fluids are dominant by the enriched mantle-derived fluid. Nd-Pb isotopes of ore and altered
rocks are different either from those of the surrounding granites and the basement metamorphic rocks or from those of Mesozoic
asthenosphere-derived basalts. Instead, they are consistent with those of Mesozoic lithospheric mantle-derived lamprophyres in the
Jiaodong district. However, their initial 87Sr/86Sr ratios are higher than those of the lamprophyres and even higher than the surrounding
granites. The Sr-Nd-Pb isotopic characteristics indicate that the ore-forming fluids and ore-forming materials were derived from the
enriched lithospheric mantle with subsequent interacted with the basement metamorphic rocks during the ascending process.

Key words: Xiadian gold deposit, H-O isotope, He-Ar isotope, Sr-Nd-Pb isotope, ore-forming fluid, ore-forming material