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引用本文:刘凯,吴涛涛,刘金龙,鲍庆中,杜守营. 大兴安岭北段图里河地区满克头鄂博组火山岩年代学及地球化学[J]. 中国地质, 2018, 45(2): 367-376.
LIU Kai,WU Taotao,LIU Jinlong,BAO Qingzhong,DU Shouying. Geochronology and geochemistry of volcanic rocks in Manketou'ebo Formation of Tulihe area, northern Da Hinggan Mountains[J]. Geology in China, 2018, 45(2): 367-376(in Chinese with English abstract).
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大兴安岭北段图里河地区满克头鄂博组火山岩年代学及地球化学
刘凯,吴涛涛,刘金龙,鲍庆中,杜守营
作者单位
刘凯 中国地质调查局沈阳地质调查中心, 辽宁 沈阳 110034 
吴涛涛 中国地质调查局沈阳地质调查中心, 辽宁 沈阳 110034 
刘金龙 中国地质调查局沈阳地质调查中心, 辽宁 沈阳 110034 
鲍庆中 中国地质调查局沈阳地质调查中心, 辽宁 沈阳 110034 
杜守营 辽宁环宇矿业咨询有限公司, 辽宁 沈阳 110031 
摘要:
对大兴安岭北段图里河地区满克头鄂博组火山岩进行了锆石U-Pb年代学及岩石地球化学研究,以便对其岩石成因和构造背景给予制约。流纹岩LA-ICP-MS锆石U-Pb定年结果表明,该地区满克头鄂博组火山岩形成时代为晚侏罗世(157±1Ma)。该组火山岩具有高硅(SiO2=69.09%~75.92%)、富碱(K2O+Na2O=8.04%~9.23%),贫镁、铁、钙的特征,属高钾钙碱性、偏铝质-弱过铝质岩石;稀土元素配分曲线呈轻稀土富集的右倾形式,(La/Yb)N=5.85~13.53,无铕异常或具有较弱的铕负异常;火山岩样品富集Rb、Th、U、K等大离子亲石元素,亏损Nb、Ta、Ti等高场强元素。Mg#值为12.14~31.01,平均值22,Nb/Ta值(6.67~27.17,平均值12.23),Rb/Sr值(0.35~3.63,平均值1.58),显示火山岩岩浆源区为下地壳。依据岩石地球化学特征、构造判别图解,结合区域构造演化特征,认为满克头鄂博组火山岩形成于蒙古-鄂霍茨克洋闭合的造山后伸展背景。
关键词:  满克头鄂博组  蒙古-鄂霍茨克洋  岩石成因  大兴安岭北段  内蒙古
DOI:10.12029/gc20180211
分类号:P588.14;P595
基金项目:中国地质调查局项目(12120114055201)资助。
Geochronology and geochemistry of volcanic rocks in Manketou'ebo Formation of Tulihe area, northern Da Hinggan Mountains
LIU Kai,WU Taotao,LIU Jinlong,BAO Qingzhong,DU Shouying
Abstract:
In this paper, the authors studied the chronology and geochemistry of volcanic rocks in Manketou'ebo Formation of Tulihe area within Da Hinggan Mountains to restrict the petrogenesis and the tectonic setting. Zircon U-Pb dating reveals that the volcanic rocks formed in (157±1) Ma, suggesting late Jurassic. The geochemical characteristics reveal that these rocks fall into the high-K calc-alkaline, metaluminous to slightly peraluminous rhyolite series, characterized by high SiO2 content (69.09%-75.92%), high alkali content (8.04%-9.23%) but low MgO, CaO and Fe2O3 content. The REE patterns reveal that the rocks are enriched in light rare earth elements with significant fractionation of HREE and LREE ((La/Yb)N=5.85-13.53), with no or lightly negative Eu anomaly. Rocks are enriched in LILE such as Rb, Th, U and K, relatively depleted in HFSE such as Nb, Ta and Ti. Mg# ratios vary from 12.14 to 31.01, 22 on average; Nb/Ta ratios vary from 6.67 to 27.17, 12.23 on average; Rb/Sr ratios vary from 0.35 to 3.36, 1.58 on average, implying that the magmatic source was the lower crust. According to the geochemical features, discrimination diagrams of tectonic setting and regional tectonic evolution, the authors hold that the volcanic rocks formed in the post-orogenic extension setting after the closure of Mongol-Okhotsk Ocean.
Key words:  Manketou'ebo  Mongol-Okhotsk Ocean  petrogenesis  northern Da Hinggan Mountains  Inner Mongolia