| 甘肃省阳山金矿床石英脉中锆石SHRIMP U-Pb年代学研究 |
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| 引用本文：.2005.A SHRIMP U_Pb chronological study of zircons from quartz veins of Yangshan gold deposit, Gansu Province[J].Mineral Deposits,24(2):141~150 |
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| 基金项目:中国人民武装警察部队黄金指挥部科研专项基金资助项目(编号 HJ02001) |
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| 中文摘要:为研究阳山特大微细浸染型金矿床的成矿时代，文章结合阴极发光对矿区不同类型石英(细)脉中锆石进行了SHRIMP U_Pb年龄的精确测定。结果表明，微细浸染型矿石中锆石呈自形柱状，韵律性环带结构发育，Th/U比值集中于0.5～1.5之间，具岩浆岩锆石特征，锆石206Pb/238U年龄有3组，分别为(197.6±1.7) Ma、(126.9±3.2) Ma和(51.2±1.3) Ma，其中前一组年龄与矿区斜长花岗斑岩脉的形成时代一致，而后两组年龄指示矿区存在白垩纪及第三纪隐伏岩浆岩体，表明阳山微细浸染型金矿床的形成与中、新生代3次岩浆热液活动有关。矿区含明金石英脉型矿石中所测得的锆石年龄均老于围岩时代。不同时代多期次热液活动在空间上的耦合是形成阳山金矿床的重要因素。 |
| 中文关键词:地球化学 微细浸染型 金矿床 锆石 SHRIMP年龄 阴极发光 甘肃 |
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| A SHRIMP U_Pb chronological study of zircons from quartz veins of Yangshan gold deposit, Gansu Province |
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| Abstract:The Yangshan gold deposit is a supperlarge fine_grained disseminated gold deposit in southern Gansu Province. In this paper, cathodoluminescence image (CL) and ion probe U_Pb dating (SHRIMP) techniques were used to determine the metallogenic age. It is found that zircons from quartz veins of fine-grained disseminated gold ores show characteristics of magmatic zircon, with pillar idiomorphism, rhythmic crystallization and main Th/U ratio of 0.5～1.5. Three main populations of zircons were obtained, giving average 206Pb/238 U ages of (197.6±1.7) Ma, (126.9±3.2) Ma and (51.2±1.3) Ma respectively. The first age corresponds to K-Ar age of the plagiogranite dike, while the last two ages indicate that buried Cretaceous and Tertiary intrusives exist in the ore district, suggesting that the Yangshan gold deposit is genetically related to the three times of magmatic hydrothermal activities. By contrast, zircons from quartz vein type gold ores in the ore district are much older than the host rock, indicating that quartz veins were formed earlier and were not contaminated by later magmatic fluids. It is concluded that coupling of multiperiodic hydrothermal activities in the ore district contributed to mineralization of the Yangshan gold deposit. |
| keywords:geochemistry, disseminated type, gold deposit, zircon, SHRIMP, cathodolu minescence image, Gansu |
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