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现代地质 ›› 2017, Vol. 31 ›› Issue (04): 683-696.

• 岩石学 • 上一篇    下一篇

大兴安岭西缘玛尼吐组火山岩成因及构造指示

李英雷1(), 徐国1,2, 刘汇川3(), 白灵麒1, 苏银春1, 刘小女1   

  1. 1.内蒙古自治区岩浆活动成矿与找矿重点实验室 内蒙古自治区地质调查院,内蒙古 呼和浩特 010020
    2.中国地质大学(武汉) 地球科学学院,湖北 武汉 430074
    3.中山大学 地球科学与工程学院,广东 广州 510275
  • 收稿日期:2016-06-25 修回日期:2017-01-12 出版日期:2017-08-10 发布日期:2017-09-15
  • 通讯作者: 刘汇川,特聘研究员,1986年出生,构造地质学专业,从事区域大地构造研究。Email: liuhuichuan1986@126.com
  • 作者简介:李英雷,硕士,工程师,1986年出生,构造地质学专业,从事区域地质矿产调查工作。Email: cumtlyl@126.com
  • 基金资助:
    国家自然科学基金项目(41502210);中国地质调查局“内蒙古新巴尔虎右旗地营子等六幅1:5万地质矿产综合调查”子项目(12120115031301)

Petrogenesis and Tectonic Implication of Volcanic Rocks from Manitu Formation in the Western Great Xing’an Range

LI Yinglei1(), XU Guo1,2, LIU Huichuan3(), BAI Lingqi1, SU Yinchun1, LIU Xiaonü1   

  1. 1. Inner Mongolia Key Laboratory of Magmatic Mineralization and Ore-Prospecting,Geological Survey Institute of Inner Mongolia, Hohhot, Inner Mongolia 010020, China
    2. School of Earth Sciences, China University of Geosciences, Wuhan, Hubei 430074, China
    3. School of Earth Science and Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
  • Received:2016-06-25 Revised:2017-01-12 Online:2017-08-10 Published:2017-09-15

摘要:

我国东北地区分布有大量中生代(侏罗纪至白垩纪)火山岩。选取大兴安岭西缘玛尼吐组粗安岩-粗面英安岩-流纹岩为研究对象,研究结果显示它们为高钾钙碱性的火山岩,主量、微量元素含量变化较大,SiO2含量为56.71%~71.85%,Na2O+K2O含量为5.92%~10.18%,Na2O/K2O比值较高,为0.78~1.33,Mg#为30.6~56.4。玛尼吐组火山岩的稀土元素配分图和微量元素蛛网图右倾明显,可见明显的Nb、Ta、Ti、Sr和Eu负异常(Nb*=0.17~0.71,Sr*=0.24~1.15,Eu*=0.49~0.77)。稀土总量较高,为200×10-6~949×10-6。结果分析可知,玛尼吐组火山岩源岩与霍林河火山岩源岩相似,均为混合了少量先存古老地壳的新生基性下地壳。新生基性下地壳部分熔融形成安山质岩浆,并经角闪石+斜长石+钾长石+磷灰石+钛磁铁矿等的分离结晶形成了玛尼吐组粗安岩-粗面英安岩-流纹岩。玛尼吐组火山岩显著的岛弧地球化学特征说明其形成于与太平洋俯冲有关的岛弧环境。

关键词: 大兴安岭, 玛尼吐组, 火山岩, 太平洋俯冲, 钙碱性岩

Abstract:

Different tectonic settings have been proposed for the Mesozoic volcanic rocks in northeast China, including the mantle plume, subduction of the Pacific Ocean and post-collisional extension associated with the closure of the Mongol-Okhotsk ocean. In this paper, we carried out geochemical studies on the andesite-dacite-rhyolite in Manitu Formation of the western Great Xing’an Range (NE China). Samples show variable major and trace element compositions with SiO2=56.71%-71.85%, Na2O+K2O=5.92%-10.18%, Na2O/K2O=0.78-1.33,Mg#=30.6-56.4. Chondrite and primitive mantle normalized REE patterns and spidergrams show significant Nb, Ta, Ti, Sr and Eu negative anomalies (Nb*=0.17-0.71, Sr*=0.24-1.15, Eu*=0.49-0.77) and high total REEs contents. These results suggest that the source magmas of the Manitu volcanic rocks were derived from a preexistent juvenile crust and a subordinate recycled crustal component. A fractional assemblage of hornblende+plagioclase+K-feldspar+apatite+titanomagnetite was responsible for the systematic elements variations from the andesite to rhyolite. This interpretation is consistent with the tectonic model that the Manitu volcanic rocks were generated in an arc/back-arc tectonic setting in response to the Pacific Ocean subduction.

Key words: Great Xing’an Range, Manitu Formation, volcanic rock, subduction of the Pacific Ocean, calc-alkaline rock

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