江西省武功山地区浒坑花岗岩的锆石U-Pb定年及元素地球化学特征

Zircon LA-ICPMS U-Pb dating of Hukeng granite in Wugongshan area,Jiangxi Province and its geochemical characteristics

浒坑花岗岩侵入体位于武功山复式背斜东南翼,发育有大型的浒坑石英脉型钨矿床,其是武功山钨、铜、铋、钼多金属成矿带的重要组成部分。本文通过对浒坑白云母花岗岩精确的锆石 LA-ICPMS U-Pb 测年,测得其成岩时代为151.6±2.6Ma,属晚侏罗世,对应于华南中生代第一次花岗岩侵位事件(164～153Ma);其花岗岩岩浆的形成温度为676～695℃。通过浒坑花岗岩主微量元素结果的分析,认为浒坑白云母花岗岩属于高钾钙碱性系列,为准铝质—弱过铝质的分异 S 型花岗岩,其源岩为富粘土的泥质来源,形成于岩石圈伸展减薄环境。

Hukeng granite intrusion locates in southeast limb of Wugongshan compound anticline, where developed large scale Hukeng tungsten deposit that is an important part of Wugongshan W-Cu-Bi-Mo poiy-metallic metallogenic belt. Through precise LA- ICPMS U-Pb dating of zircon from Hukeng granite, the crystallization age of the intrusion was determined to be 151.6 ± 2. 6Ma, corresponding to Late Jurassic era and ascribed to the first intruding event of granites in Mesozoic era in South China （ 164 - 153Ma）. The formation temperature of granite magma was 676 -695℃. Through the analysis of major and trace elements of Hukeng muscovite granites, they belonged to high-K calc-alkaline series and were thought to be peraluminous differentiation S-type granites. They should mainly derive from clay-enriched argillaceous rock source in upper crust and form under lithospheric extensional and thinning environment.