张超, 张渝金, 权京玉, 郭威, 郭建刚, 王青召, 李伟, 汪岩, 宋维民, 那福超, 谭红艳. 内蒙古扎鲁特盆地坤都地区满克头鄂博组流纹岩锆石U-Pb年龄及岩石成因[J]. 地质通报, 2018, 37(9): 1633-1643.
    引用本文: 张超, 张渝金, 权京玉, 郭威, 郭建刚, 王青召, 李伟, 汪岩, 宋维民, 那福超, 谭红艳. 内蒙古扎鲁特盆地坤都地区满克头鄂博组流纹岩锆石U-Pb年龄及岩石成因[J]. 地质通报, 2018, 37(9): 1633-1643.
    ZHANG Chao, ZHANG Yujin, QUAN Jingyu, GUO Wei, GUO Jiangang, WANG Qingzhao, LI Wei, WANG Yan, SONG Weimin, NA Fuchao, TAN Hongyan. Zircon U-Pb geochronology and petrogenesis of rhyolites in Manketouebo Formation from the Kundu area in Jarud Basin, Inner Mongo-lia[J]. Geological Bulletin of China, 2018, 37(9): 1633-1643.
    Citation: ZHANG Chao, ZHANG Yujin, QUAN Jingyu, GUO Wei, GUO Jiangang, WANG Qingzhao, LI Wei, WANG Yan, SONG Weimin, NA Fuchao, TAN Hongyan. Zircon U-Pb geochronology and petrogenesis of rhyolites in Manketouebo Formation from the Kundu area in Jarud Basin, Inner Mongo-lia[J]. Geological Bulletin of China, 2018, 37(9): 1633-1643.

    内蒙古扎鲁特盆地坤都地区满克头鄂博组流纹岩锆石U-Pb年龄及岩石成因

    Zircon U-Pb geochronology and petrogenesis of rhyolites in Manketouebo Formation from the Kundu area in Jarud Basin, Inner Mongo-lia

    • 摘要: 为研究内蒙古扎鲁特盆地坤都地区晚侏罗世火山岩的构造属性,对研究区内流纹岩开展了锆石U-Pb定年和原位Lu-Hf同位素研究。锆石U-Pb定年结果显示,流纹岩形成于151.2±1.2Ma,属于晚侏罗世。岩石地球化学研究表明,火山岩具高硅富碱、贫镁钙的特征,稀土元素总量为110.38×10-6~138.88×10-6,轻、重稀土元素分馏中等,弱负Eu异常(δEu=0.72~0.98),微量元素特征为富集Cs、Rb、Ba和轻稀土元素,强烈亏损Sr、P、Ti,相对亏损Nb、Ta,εHft)值为-10.1~4.9,对应的地壳模式年龄(TDMC)为1192~3639Ma,反映其岩浆来源于元古宙、太古宙地壳物质的部分熔融,之后经历矿物分离结晶作用。通过对比大兴安岭地区同时代岩浆-构造活动,研究区满克头鄂博组流纹岩形成于后造山伸展背景,与蒙古-鄂霍茨克造山后伸展作用有关。

       

      Abstract: Age and tectonic implications of the Late Jurassic rhyolites in Kundu area of Jarud Basin were studied by using zircon U-Pb dating, in situ Lu-Hf isotopic analysis, petrographic analysis and other geochemical methods. LA-ICP-MS zircon U-Pb dating results show that the rhyolites were formed in Late Jurassic, with their formation age being 151.2±1.2Ma. The geochemical study suggests that rhyolites are rich in silicon and alkali, but poor in calcium and magnesia. The REE values of them are between 110.38×10-6 and 138.88×10-6, displaying medium LREE-enriched and HREE-depleted REE patterns(La/Yb)N=6.24~7.43, with weak negative Eu anomaly (δEu=0.72~0.98). The trace element geochemistry is characterized evidently by enrichment of Cs, Rb, Ba and LREE, strong depletion of Sr, P, Ti, and mediate depletion of Nb, Ta, with the εHf(t) values varying from -10.1~4.9, corresponding to TDMC model ages of 1192~3639Ma, which shows that the rhyolitc magma originated mainly from the partial melting of Proterozoic and Archean crustal rocks, and suffered fractional crystallization. Based on the above result, in combination with previous studies of the contemporaneous magma-tectonic activities in Da Hinggan Mountains, the authors hold that the rhyolites in Manketouebo Formation were formed in an extensional setting related to Mongolia Okhotsk orogenesis

       

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