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    赣南张天堂地区岩体型钨矿晚侏罗世成岩成矿的同位素年代学证据

    Isotope chronological evidence for Upper Jurassic petrogenesis and mineralization of altered granite-type tungsten deposits in the Zhangtiantang area, southern Jiangxi

    • 摘要: 提要:摇篮寨钨矿是新近发现于赣南张天堂地区的代表性岩体型钨矿床。笔者对其含矿岩体和矿石进行了成岩成矿年龄精测,分别获得细粒似斑状白云母花岗岩锆石SHRIMP U-Pb年龄为(156.9±1.7)Ma(n=11,MSWD=3.3),浸染状辉钼矿Re-Os同位素的模式年龄为(155.2±2.3)Ma~(156.5±2.1)Ma、等时线年龄为(155.8±2.8)Ma(n=4,MSWD=0.49)。结合区域最新获得的高精度测年数据的分析,结果表明,本区钨矿床形成于晚侏罗世(集中在150~160 Ma),钨成矿和与之有密切成因关系的花岗岩类岩体成岩不存在明显时差(1~5 Ma),本区的钨锡成矿对应于华南中生代第二次大规模成矿作用。

       

      Abstract: Abstract:Located in the Zhangtiantang area, southern Jiangxi, the recently discovered Yaolanzai deposit is a typical altered granite-type tungsten deposit. Through highly precise dating of the ages of petrogenesis and mineralization of the tungsten deposit, the authors obtained a SHRIMP U-Pb zircon age of 156.9±1.7 Ma (n=11, MSWD=3.3) for porphyritic fine-grained muscovite granite and Re-Os model ages of 155.2±2.3 to 156.5±2.1 Ma and an isochron age of 155.8±2.8 Ma (n=4, MSWD=0.49) for disseminated molybdenite in ores. According to the above-mentioned ages, combined with the highly precise age data obtained at a regional scale recently, the authors conclude that the tungsten deposits in this area formed in the Upper Jurassic, with their isotopic ages clustering at 150-160 Ma. There is no significant time gap(1-5 Ma) between tungsten mineralization and petrogenesis of its closely related granitoids. The W-Sn mineralization in the area corresponds to the regional-scale Mesozoic second large-scale mineralization in South China.

       

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