郭通珍, 刘荣, 陈发彬, 白旭东, 李红刚. 青海祁漫塔格山乌兰乌珠尔斑状正长花岗岩LA-MC-ICPMS锆石U-Pb定年及地质意义[J]. 地质通报, 2011, 30(8): 1203-1211.
    引用本文: 郭通珍, 刘荣, 陈发彬, 白旭东, 李红刚. 青海祁漫塔格山乌兰乌珠尔斑状正长花岗岩LA-MC-ICPMS锆石U-Pb定年及地质意义[J]. 地质通报, 2011, 30(8): 1203-1211.
    GUO Tong-zhen, LIU Rong, CHEN Fa-bin, BAI Xu-dong, LI Hong-gang. LA-MC-ICPMS zircon U-Pb dating of Wulanwuzhuer porphyritic syenite granite in the Qimantag Mountain of Qinghai and its geological significance[J]. Geological Bulletin of China, 2011, 30(8): 1203-1211.
    Citation: GUO Tong-zhen, LIU Rong, CHEN Fa-bin, BAI Xu-dong, LI Hong-gang. LA-MC-ICPMS zircon U-Pb dating of Wulanwuzhuer porphyritic syenite granite in the Qimantag Mountain of Qinghai and its geological significance[J]. Geological Bulletin of China, 2011, 30(8): 1203-1211.

    青海祁漫塔格山乌兰乌珠尔斑状正长花岗岩LA-MC-ICPMS锆石U-Pb定年及地质意义

    LA-MC-ICPMS zircon U-Pb dating of Wulanwuzhuer porphyritic syenite granite in the Qimantag Mountain of Qinghai and its geological significance

    • 摘要: 青海祁漫塔格地区乌兰乌珠尔正长花岗岩具有高硅、高碱(AR为3.02~5.88,NK/A为1.04~1.17,A/CNK为0.96~1.07)、高TFeO/MgO和贫CaO、MgO的特征;∑REE较高,LREE略富集,轻重稀土元素分馏不十分明显,Eu负异常明显,稀土元素配分模式呈稍右倾的V字形;明显富集Rb、K、Th等大离子亲石元素,相对富集Zr、Hf等高场强元素,相对亏损Ba、Sr、P、Ti、Nb等。这些资料显示了A2型铝质花岗岩的特征,其来源可能与洋壳、岛弧建造组成的年轻地壳有关。采用LA-MC-ICPMS锆石U-Pb定年方法,获得乌兰乌珠尔正长花岗岩体的206Pb/238U年龄为388.9Ma±3.7Ma(MSWD=3.1),代表该岩体的形成年龄。结合岩石地球化学、构造特征和区域地质背景,认为该岩体形成于后造山或造山作用演化晚期相对伸展的环境。

       

      Abstract: Wulanwuzhuer porphyritic syenite granite in Qimantag region is characterized by high silica, high alkali (AR 3.02-5.88,NK/A 1.04-1.17,and A/CNK 0.96-1.07), high TFeO/MgO ratio, poor CaO and MgO, relatively high ∑REE,slight enrichment of LREE,indistinct light and heavy REE fractionation,negative Eu anomalies,somewhat right-oblique “V”-shaped REE patterns,significant enrichment of Rb, K, Th and other large ion lithophile elements, relative enrichment of Zr, Hf and other high field strength elements, and relative depletion of such elements as Ba, Sr, P, Ti, and Nb. These characteristics suggest an aluminous A2-type granite, whose formation might have been associated with the young crust formed by oceanic crust and island arc. Using LA-MC-ICPMS zircon U-Pb dating, the authors obtained the 206Pb/238U age of Wulanwuzhuer granite of 388.9±3.7 Ma(MSWD=3.1),which represents the formation age of the rock. In combination with geochemical and structural features and regional geological setting, the authors hold that the intrusive body was formed in a relative extension environment during post-orogenic or late orogenic evolution.

       

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