摘要
对大兴安岭满归地区新元古界—下寒武统大网子组变中酸性火山岩进行锆石U-Pb同位素年代学研究,探讨其形成时代及地质意义。大网子组由变安山岩、变英安岩、变流纹岩和少量变晶屑凝灰岩组成,缺少板岩、变砂岩、片岩等沉积岩夹层。通过对变安山岩进行锆石U-Pb同位素年龄测定,获得其锆石206 Pb/238 U加权平均年龄为(199±1)Ma,表明大网子组变中酸性火山岩形成于早侏罗世早期,非前人认为的形成于新元古代—早寒武世。额尔古纳地块早侏罗世火山岩为漠河盆地提供了物源,表明额尔古纳地块在早侏罗世处于火山-岩浆弧构造背景。该研究为蒙古—鄂霍茨克洋闭合过程中的地球动力学研究提供了新资料。
Through the zircon U-Pb isotopes chronology research of the meta-intermediate-acidic volcanic rocks of Neoproterozoic-Lower Cambrian Dawangzi Formation in Mangui area of Da Hinggan Mountains,the authors explored the forming age and geological significance of the rocks.Dawangzi Formation is composed of meta-andesite,meta-dacite,rhyolite and a small amount of meta-crystalline tuff,and lacks interbeds of sedimentary rocks such as slate,metasandstone and schist.The authors determined the zircon U-Pb isotopes age of the meta-andesite,and the zircon 206 Pb/238 U weighted mean age is(199±1)Ma,indicating that the forming age of Dawangzi Formation meta-intermediate-acidic volcanic rocks is the early stage of Early Jurassic,not Neoproterozoic-Early Cambrian as in previous research.Early Jurassic volcanic rocks distributed in Erguna Block provide a provenance for Mohe Basin.Erguna Block was in the volcano-magmatic arc tectonic background in Early Jurassic.This research supplies new data for the geodynamics study during the closure of Mongolia-Okhotsk Ocean.
作者
李中会
李睿杰
李阳
沙环宇
LI Zhonghui;LI Ruijie;LI Yang;SHA Huanyu(Heilongjiang Institute of Geological Survey,Harbin 150036,China;Heilongjiang QiqiharInstitute of Geological Exploration,Qiqihar 161006,China)
出处
《中国地质调查》
2020年第1期47-52,共6页
Geological Survey of China
基金
中国地质调查局“黑龙江1∶25万漠河幅、漠河县幅区调修测(编号:1212011120653,1212010881209)”项目资助
