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河北省石湖金矿位于阜平幔枝构造核部中南段,其围岩主要是太古宇阜平群,是冀西目前已发现的唯一大型金矿。为研究石湖金矿的成矿时代,重点对含金石英脉中锆石进行了阴极发光分析和LA-ICP-MS U-Pb同位素测年。结果表明:锆石形态为自形-半自形,环带特征明显,Th/U比值大多大于0.1,为典型的岩浆锆石。锆石U-Pb年龄主要分为两组,其中一组~(207)Pb/~(206)Pb年龄主要位于(2 569±41)-(2 014±38)Ma之间,年龄数据在谐和图上基本位于一致曲线下方,显示放射成因铅明显有不同程度的丢失,其年龄数据与一致曲线的上交点年龄为(2 492±82)Ma,表示岩浆锆石的结晶年龄,可代表阜平群TTG片麻岩的结晶年龄;另一组~(206)Pb/~(238)U年龄为(136±4)Ma,结合含矿地质体之间的空间位置关系,综合表明石湖金矿主要成矿事件发生在(136±4)Ma之后。石英脉中没有热液锆石,锆石来自围岩。
The Shihu gold deposit in Hebei Province is located in the central-southern part of the core of the Fuping-mantle branch structure. Its surrounding rock is mainly composed of the Archean UF-Ping Group and is the only large-scale gold deposit discovered in western Hebei. In order to study the metallogenic epoch of Shihu gold deposit, cathodoluminescence analysis and LA-ICP-MS U-Pb isotope dating of zircons in gold-bearing quartz veins have been carried out. The results show that the zircons are in the shape of automorphic - semicircle, with obvious zonal characteristics, and the Th / U ratios are mostly greater than 0.1, which are typical magmatic zircons. The U-Pb ages of zircons are mainly divided into two groups. The age of a group of (207) Pb / ~ (206) Pb mainly lies between (2 569 ± 41) - (2 014 ± 38) Ma, And the figure is basically located below the consistent curve, indicating that the cause of lead was significantly different from the loss of the lead, the age of the data and the coincident curve of the upper point of the age (2 492 ± 82) Ma, said the magmatic zircon zircon crystallization age, on behalf of Fu In the other group, the age of ~ (206) Pb / ~ (238) U was (136 ± 4) Ma, and the spatial location of the TTG gneisses in Pingping group was combined with that of the ore- The major metallogenic event occurred after (136 ± 4) Ma. There is no hydrothermal zircon in quartz veins, and zircon comes from the surrounding rock.