科研之友
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摘要
Noble gases are recognized as being exceptional tracers of volatile sources during mineralization He, Ne and Ar abundance and isotopic compositions from 23 silicate and sulfide separates in the Jinchuan Cu-Ni-PGE sulfide deposit, West China, have been investigated by melting extraction MM5400 mass spectrometer The results show that (3)He/(4)He ratios in silicate minerals (av 0 239Ra) are slightly lower than those in sulfide (av 0 456Ra), and decrease from olivine (av 0 291Ra), orthopyroxene (av 0 215Ra) to clinopyroxene (av 0 174Ra) (20)Ne/(22)Ne and (21)Ne/(22)Ne ratios are plotted Into the ranges between MORB line and continental crust line (3)He/(4)He and (40)Ar/(36)Ar of olivine (Olv) and orthopyroxene (Opx) deducted by radiogenic He and Ne are close to the He and Ar isotopic ranges of subcontinental lithosphere mantle (SCLM) He, Ne and Ar isotopic compositions suggested that SCLM, continental crust (CC) and air saturated water (ASW) three end-members were involved into ore-forming magma of the Jinchuan Cu-Ni-PGE sulfide deposit The segregation of immiscible sulfide liquid from magma took place at the early stage of magma evolution The primary ore forming magma had been formed by partial melting of SCLM, and undergone two stages of evolution It had been assimilated possibly with wall rock which resulted in the sulfur supersaturating in silicate magma and segregation of immiscible sulfide melt and formed a mixed component (MC) with SCLM and continental crust (CC) signatures The mixed component (MC) emplaced into upper chamber and mixed with a high proportion of deep circulatory ASW which induced sulfur supersaturating of ore-forming magma and in-situ formed the disseminated ore in upper magma chamber
- 出版日期2010-11
- 单位西安地质矿产研究所; 中国科学院地质与地球物理研究所; 兰州大学; 中国科学院地质与地球物理研究所兰州油气资源研究中心
