李航, 王明, 解超明, 曾孝文, 董宇超, 于云鹏, 罗安波. 西藏冈底斯带阿索构造混杂岩南侧亚布努马花岗斑岩地球化学特征及锆石U-Pb年龄[J]. 地质通报, 2018, 37(8): 1510-1518.
    引用本文: 李航, 王明, 解超明, 曾孝文, 董宇超, 于云鹏, 罗安波. 西藏冈底斯带阿索构造混杂岩南侧亚布努马花岗斑岩地球化学特征及锆石U-Pb年龄[J]. 地质通报, 2018, 37(8): 1510-1518.
    LI Hang, WANG Ming, XIE Chaoming, ZENG Xiaowen, DONG Yuchao, YU Yunpeng, LUO Anbo. Geochemistry and zircon U-Pb age of granite porphyry in the Yabunuma region close to the southern margin of the Asuo structural melange belt, Gangdise, Tibet[J]. Geological Bulletin of China, 2018, 37(8): 1510-1518.
    Citation: LI Hang, WANG Ming, XIE Chaoming, ZENG Xiaowen, DONG Yuchao, YU Yunpeng, LUO Anbo. Geochemistry and zircon U-Pb age of granite porphyry in the Yabunuma region close to the southern margin of the Asuo structural melange belt, Gangdise, Tibet[J]. Geological Bulletin of China, 2018, 37(8): 1510-1518.

    西藏冈底斯带阿索构造混杂岩南侧亚布努马花岗斑岩地球化学特征及锆石U-Pb年龄

    Geochemistry and zircon U-Pb age of granite porphyry in the Yabunuma region close to the southern margin of the Asuo structural melange belt, Gangdise, Tibet

    • 摘要: 西藏中冈底斯北部尼玛县阿索乡亚布努马地区东侧出露一处花岗斑岩岩脉,LA-ICP-MS锆石U-Pb测年结果显示,该花岗斑岩的形成时代为晚侏罗世(161.2±5.9Ma)。全岩地球化学数据显示其高硅、富碱、富铝的特征,属于碱性准铝质花岗斑岩; 富集轻稀土元素,轻、重稀土元素分异明显,具有明显的负Eu异常,富集Rb、Pb等大离子亲石元素,亏损Ba、Sr元素及Nb、Ta、Ti、U等高场强元素,形成于岛弧环境。其源区可能为来自俯冲带增厚下地壳的深熔作用,结合区域上同时代的岩浆事件,亚布努马花岗斑岩应该形成于以班公湖-怒江洋南向俯冲为动力背景的陆缘弧环境。

       

      Abstract: The granite porphyry vein in the Yabunuma area is located in Asuo and Nyima area of northern Central Gangdise. LAICP-MS zircon U-Pb age of 161.2±5.9Ma indicates emplacement during the Late Jurassic. The bulk rock geochemical analyses indicate the characteristics of high silica, rich alkali and Al, suggesting alkali metaluminous granite porphyry. The granite porphyry samples are rich in LREE, the fractionation between LREE and HREE is strong and shows obvious negative Eu anomalies, with the characteristics of enrichment of Rb and Pb, depletion of Ba, Sr, Nb, Ta, Ti and U, suggesting an island-arc setting. The granite porphyry is likely to root in anatexis of thickened lower crust. Considering coeval magma event in the vicinity, the authors hold that granite porphyry from Yabunuma region should have formed in an active epicontinental environment on the background of the southern subduction of Bangong Co-Nujiang Tethyan Ocean crust.

       

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