王正庆, 范洪海, 陈东欢, 谢财富, 肖为, 罗桥花, 郑可志, 管太阳, 林子瑜. 桂东北苗儿山张家花岗岩LA-ICP-MS锆石U-Pb年龄与地球化学特征[J]. 地质通报, 2018, 37(5): 895-907.
    引用本文: 王正庆, 范洪海, 陈东欢, 谢财富, 肖为, 罗桥花, 郑可志, 管太阳, 林子瑜. 桂东北苗儿山张家花岗岩LA-ICP-MS锆石U-Pb年龄与地球化学特征[J]. 地质通报, 2018, 37(5): 895-907.
    WANG Zhengqing, FAN Honghai, CHEN Donghuan, XIE Caifu, XIAO Wei, LUO Qiaohua, ZHENG Kezhi, GUAN Taiyang, LIN Ziyu. Geochronology and geochemistry of the Zhangjia granitic pluton in the Miaoershan uranium orefield, Northeastern Guangxi Province[J]. Geological Bulletin of China, 2018, 37(5): 895-907.
    Citation: WANG Zhengqing, FAN Honghai, CHEN Donghuan, XIE Caifu, XIAO Wei, LUO Qiaohua, ZHENG Kezhi, GUAN Taiyang, LIN Ziyu. Geochronology and geochemistry of the Zhangjia granitic pluton in the Miaoershan uranium orefield, Northeastern Guangxi Province[J]. Geological Bulletin of China, 2018, 37(5): 895-907.

    桂东北苗儿山张家花岗岩LA-ICP-MS锆石U-Pb年龄与地球化学特征

    Geochronology and geochemistry of the Zhangjia granitic pluton in the Miaoershan uranium orefield, Northeastern Guangxi Province

    • 摘要: 对张家岩体乍古田矿床及张家矿床的2件赋矿围岩样品,开展LA-ICP-MS锆石U-Pb同位素定年,获得乍古田矿床赋矿围岩形成年龄为218.0±1.4Ma,张家矿床赋矿围岩形成年龄为226.8±5.7Ma。另外,对张家岩体8件样品的主量、微量元素及Sr-Nd同位素分析测试显示,张家花岗岩富硅(SiO2=74.35%~76.29%)、高铝(Al2O3=12.54%~14.03%)、高碱(Na2O+K2O=6.95%~9.17%)、低镁(MgO=0.34%~0.45%)、低钙(CaO=0.68%~1.03%)、低钛(TiO2=0.106%~0.18%),属高钾钙碱性花岗岩;富集Rb,亏损Ba、Sr,Rb/Sr值高,属于低Ba-Sr花岗岩;轻稀土元素富集,负Eu异常;富U(平均21.5×10-6),Th/U值低(平均1.63),有利于铀矿化;(87Sr/86Sr)i高(约0.7247),低εNdt)值(平均-13.95),二阶段Nd模式年龄为2.07~2.19Ga。张家花岗岩属于强过铝质S型花岗岩,可能是华夏板块古元古代基底变泥质岩经部分熔融形成的。

       

      Abstract: Two samples were collected near the Zhagutian uranium ore deposit and Zhangjia uranium ore deposit respectively to carry out LA-ICP-MS zircon U-Pb isotopic dating. The analytical result demonstrates that the formation age of the host rock in the Zhagutian uranium ore district is 218.0±1.4Ma, whereas the formation age of the host rock in the Zhangjia uranium ore district is 226.8±5.7Ma. Furthermore, the Zhangjia granite is characterized by high SiO2 (74.35%~76.29%), Al2O3 (12.54%~14.03%) and (Na2O+K2O) (6.95%~9.17%), but low MgO (0.34%~0.45%), CaO (0.68%~1.03%) and TiO2 (0.106%~0.18%), so it belongs to high-K calc-alkaline series granite. The Zhangjia granite is rich in Rb, and poor in Ba, Sr with high Rb/Sr ratio, so it belongs to low Ba-Sr granite series. The granite is rich in LREEs with negative Eu anomalies. Meanwhile, The granite is rich in U (21.5×10-6 on average)with low Th/U ratio (1.63 on average), so it is very favourable for uranium mineralization. The granite has high (87Sr/86Sr)i (~0.7247), low εNd (t) (-13.95 on average) and its two-stage Nd isotopic model ages are (2.07~2.19Ga). The Zhangjia granite belongs to strongly peraluminous S-type granite. It probably originated from partial melting of Proterozoic sedimentary metamorphic rocks.

       

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