内蒙古奈林沟金矿床C-H-O同位素地球化学特征

为了查明奈林沟金矿床的成矿物质来源及矿床成因,分别对氢、氧同位素和碳、氧同位素进行了测试分析。石英流体包裹体氢、氧同位素研究表明:δ18O变化范围在-3.6‰~0.2‰,平均值为-1.71‰,石英的δD介于-115‰~-98‰,平均值为-105.9‰,说明成矿流体与岩浆作用关系密切,原始岩浆水是早期成矿流体主要来源,后期则有大量的大气降水混入,是岩浆水与大气降水共同组成的混合水。方解石的碳、氧同位素研究表明:δ13C平均值为-4.54‰,与地幔δ13C值-5.5‰相近;δ18O平均值为7.86‰,与花岗岩δ18O的变化范围7‰~13‰相符,说明成矿流体与花岗岩质岩浆热液有关。综合分析认为,奈林沟金矿床属于浅成中低温重熔岩浆热液型金矿床。

Geochemical characteristics of C-H-O isotopes in Nailingou gold deposit,Inner Mongolia

In order to find out the source of ore-forming materials and the genesis of Nailingou gold deposit ,the paper respectively investigated and analyzed C-H-O isotopes.The hydrogen and oxygen isotope studies of fluid inclu-sions in quartz shows that δ18 O ranges between -3.6‰ -0.2 ‰,and average is -1.71‰,δD of the quartz chan-ges from -115‰to -98‰with the mean -105.9‰,showing that the ore-forming fluids are closely related to the magmatism.The early sources of ore-forming fluids were primary magmatic water ,and later mixed with a large amount of atmospheric precipitation ,a mixture of magmatic water and meteoric water .The carbon and oxygen isotope analysis of Calcite in Nailingou gold deposit shows that δ13 C average is -4.54 ‰,approaching to the δ13 C -5.5 ‰of man-tle,and δ18 O （ SMOW） is 7.86 ‰,coinciding with the δ18 O range 7 ‰-13 ‰ of the Granite,while different from that of Andesite ,which indicate that the ore-forming fluids were derived from granite body .