今天是2018年06月25日

大兴安岭中段早三叠世O型埃达克岩的 发现及其大地构造意义

DOI:10.3799/dqkx.2017.136

作者:李世超,张凌宇,李鹏川,施璐,郑常青

联系地址:吉林大学地球科学学院,吉林长春 130061

摘要:为了研究大兴安岭中段地区早三叠世的构造背景问题,以下三叠统哈达陶勒盖组火山岩为研究对象,通过野外观测和X射线荧光光谱分析法、等离子质谱法分别对样品的主量、微量元素进行了测试.结果显示哈达陶勒盖组火山岩是一套中酸性钙碱系列岩石组合,具有高Sr、低Yb与Y和高Sr/Y的特点,为钠质(O型)埃达克岩.结合区域资料认为,古亚洲洋于早三叠世时期闭合的碰撞应力使贺根山-嫩江-黑河构造带活化,推动构造带内年轻地壳由南向北俯冲,进而推动古生代残留洋壳向更深的地幔插入,在此过程中加热并熔融、喷出地表形成哈达陶勒盖组埃达克岩,并在山间盆地沉积了湖相碎屑堆积-老龙头组.

关键字:早三叠世;O型埃达克岩;哈达陶勒盖组;大兴安岭中段;地球动力学;岩石学.

Discovery and Tectonic Implications of Early Triassic O-Type Adakite in Middle of Great Xingan Range

Author:Li Shichao, Zhang Lingyu, Li Pengchuan, Shi Lu, Zheng Changqing

Author Address:College of Earth Sciences, Jilin University, Changchun 130061, China

Abstract:In order to study the tectonic setting of the Early Triassic of the middle of the Greater Xingan Range, the volcanic rocks of Lower Triassic Hadataolegai Formation was studied by field observation. Respectively, the main elements and trace elements were analyzed by XRF and ICP-MS. The results show that the volcanic rocks are a series of calcareous series rocks with high Sr, low Yb, Y and high Sr/Y ratios, showing geochemical features of O-type adakites are related to subduction of oceanic slab. we suggests Paleo-Asian Ocean collision along the line of Silumulon River-Changchun-Yanji which activated Hegenshan-Nenjiang-Heihe structural belt in Early Triassic. The collision pushed the young crust to subduct northward along Hegenshan-Nenjiang-Heihe line. The residual Paleozoic oceanic crust are advanced to the deeper mantle melting and then the Hadataolegai Formation adakites were formed. At the same time, the Laolongtou Formation that is lacustrine clastic sediments was deposited in the intermountain basin.

Keyword:Early Triassic; O-type adakite; Hadataolegai Formation; middle of Greater Xingan Range; geodynamics; petrology.

 

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作者简介:李世超(1980-),男,博士,副教授,主要从事构造地质学教学与研究工作.ORCID: 0000-0003-3928-2132. E-mail: lsc@jlu.edu.cn

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