小秦岭地区文峪和东闯石英脉型金矿床铅及硫同位素研究

小秦岭地区文峪和东闯金矿床均是华北地台南缘的大型金矿床，金和金(铅）矿化主要在太古宙太华群变质岩层内呈脉状产出，并且同中生代燕山期花岗岩类具密切的时空分布关系。文章对文峪金矿床、东闯金（铅）矿床、花岗岩类侵入岩和变质岩地层的硫和铅同位素组成进行了系统研究，对不同地质体的硫和铅同位素变化特征进行了详细讨论。研究结果表明：中生代花岗岩体起源于太古言变质岩的重熔和岩浆结晶分异作用。金的成矿作用发生在中生代燕山期，成矿物质主要来自花岗岩类侵入岩，岩浆热流体对太古富变质岩地层的淋滤作用亦为金矿床的形成提供了部分物质来源。

Lead and Sulfur Isotopic Studies of the Wenyu and the Dongchuang Quartz Vein Type Gold Deposits in Xiaoqinling Area, Henan and Shaanxi Provinces, Central China

The Wenyu gold deposit and the Dongchuang gold (lead) deposit are located in the Yushan uplift at southern margin of the North China craton. Gold and gold (lead) mineralizations occur within the Archean metamorphosed volcano-sedimentary sequences of the Taihua Group, surrounded by a number of Mesozoic Yanshanian granitoid stocks and dykes. Sulfur isotopic analysis was made for eighty-one sulfide (pyrite, galena, chalcopyrite and sphalerite) samples from gold- and gold (lead)-bearing quartz veins, Archean amphibolite and plagioclase gneiss, Mesozoic Yanshanian granitoid stocks and dykes at Wenyu and Dongchuang as well as their neighboring areas, and the results reveal that sulfur of the ore fluids was mainly derived from a mixed source of Mesozoic Yanshanian igneous rocks and Archean metamorphosed volcano-sedimentary rocks. Lead isotope data of amphibolite define a correlation line with the slope corresponding to an age of 2350 86 Ma. In contrast, Kfeldspar of the Mesozoic Yanshanian granitoids is characterized by high content of radiogenic lead. On the plot, lead data points of twelve sulfide samples from the Wenyu gold deposit, five sulfide samples from the Dongchuang gold (lead) deposit and one amphibolite sample constitute a mixing line cutting the Pb-growth curves of the upper crust, the orogen, the lower crust and the mantle. Nine sulfide samples from the Wenyu deposit and eleven sulfide samples from the Dongchuang deposit fall between the region of amphibolite and that of the Mesozoic Yanshanian granitoids, and constitute another Ph-mixing line. Lead isotopic analyses indicate that Late Archean supracrustal rock was the initial lead source for the Mesozoic Yanshanian granitoid and the ore-bearing veins. Both sulfur and lead isotopic data show that lead, gold and other metallic elements of the orebearing vein system came from a mixed source of Archean metamorphosed volcano-sedimentary rocks and Mesozoic Yanshanian granitoids probably derived from the re-melting of previously-formed supracrustal rocks during the Mesozoic Yanshanian orogeny.