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Acta Metallurgica Sinica

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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

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