吴文彬, 王玉平, 于海峰, 李超, 李海洋, 刘永俊, 张妍, 陈丽芳, 王晓亮. 华北克拉通北缘八当山火山岩及变质石英闪长岩锆石U-Pb年龄与岩石地球化学特征[J]. 地质通报, 2019, 38(4): 592-602.
    引用本文: 吴文彬, 王玉平, 于海峰, 李超, 李海洋, 刘永俊, 张妍, 陈丽芳, 王晓亮. 华北克拉通北缘八当山火山岩及变质石英闪长岩锆石U-Pb年龄与岩石地球化学特征[J]. 地质通报, 2019, 38(4): 592-602.
    WU Wenbin, WANG Yuping, YU Haifeng, LI Chao, LI Haiyang, LIU Yongjun, ZHANG Yan, CHEN Lifang, WANG Xiaoliang. Evidence of zircon U-Pb dating and rock geochemical characteristics of Badangshan volcanic rocks and metamorphic quartz diorite on the northern margin of North China craton[J]. Geological Bulletin of China, 2019, 38(4): 592-602.
    Citation: WU Wenbin, WANG Yuping, YU Haifeng, LI Chao, LI Haiyang, LIU Yongjun, ZHANG Yan, CHEN Lifang, WANG Xiaoliang. Evidence of zircon U-Pb dating and rock geochemical characteristics of Badangshan volcanic rocks and metamorphic quartz diorite on the northern margin of North China craton[J]. Geological Bulletin of China, 2019, 38(4): 592-602.

    华北克拉通北缘八当山火山岩及变质石英闪长岩锆石U-Pb年龄与岩石地球化学特征

    Evidence of zircon U-Pb dating and rock geochemical characteristics of Badangshan volcanic rocks and metamorphic quartz diorite on the northern margin of North China craton

    • 摘要: 赤峰东部郎郡哈拉地区变质石英闪长岩侵入到八当山火山岩中。用LA-ICP-MS技术,测得赤峰郎郡哈拉地区片理化流纹岩和变质石英闪长岩锆石206Pb/238U年龄分别为387.6±2.8Ma(MSWD=0.27,n=26)和387.1±2.3Ma(MSWD=0.34,n=28),可分别代表片理化流纹岩和变质石英闪长岩的形成年龄,属于中泥盆世岩浆活动的产物。根据地球化学特征,片理化流纹岩具有高硅、碱、铝,贫铁、镁、钙及过铝质的特征,属于钙碱性系列岩浆。轻、重稀土元素分馏较弱,具有弱负Eu异常。该片理化流纹岩具富集大离子亲石元素,亏损高场强元素,有明显的Ti、Nb和Ta负异常,Ti/Y和Zr/Y值较低,显示壳源特征。变质石英闪长岩具有高铝、铁、镁、钙及过铝质的特征,属于钙碱性系列岩浆。轻、重稀土元素分馏较弱,具有弱负Eu异常。该变质石英闪长岩富集大离子亲石元素,亏损高场强元素,有明显的Ta、Nb、Y负异常,显示出壳幔混源特征。构造环境判别显示,二者形成于活动大陆边缘,是大洋板块俯冲后的产物,可能与白乃庙岛弧和华北克拉通北缘碰撞后的伸展环境有关。

       

      Abstract: Metamorphic quartz diorite intruded into the the Badangshan volcanic rocks in Langjunhala area, eastern Chifeng City. LAICP-MS zircon U-Pb dating technique constrained the age of schistosity rhyolite and quartz diorite. The results show that the ages of schistosity rhyolite and quartz diorite are 387.6±2.8Ma and 387.1±2.3Ma, aindicating the Middle Devonian magmatic activity. According to the geochemical characteristics of foliated rhyolite with high silicon, alkali, aluminum, iron, magnesium, calcium and poor peraluminous characteristics, the rocks belong to the calc alkaline series. The light and heavy REE fractionation is weak and the Eu has weak negative anomaly. The foliated rhyolite has lower Ti/Y and Zr/Y ratios, implying the source of lithospheric mantle. Metamorphic quartz diorite is characterized by high aluminium, iron, magnesium, calcium and peraluminous, belonging to calcalkaline series magma. The fractionation of light and heavy rare earth elements is weak, with weak negative Eu anomaly. The metamorphic quartz diorite is enriched in large ion lithophile elements and depleted in high field strength elements. It has obvious negative anomalies of Ta, Nb and Y, implying mixed source characteristics of crust and mantle. Tectonic environment discriminations show that it formed on the active continental margin and was the product of subduction of the oceanic plate, probably related to the extensional environment after the collision between the Bainaimiao island arc and the northern margin of the North China craton.

       

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