摘要
大兴安岭北段新发现一条韧性剪切带--新巴尔虎右旗韧性剪切带。根据野外露头观测,该韧性剪切带为左行-逆断层性质。韧性剪切带内变形的最年轻地质体为早三叠世花岗闪长岩,其被侏罗系覆盖,且下侏罗统柴河组未发生韧性变形。通过SHRIMP锆石U-Pb测年,得出早三叠世花岗闪长岩的年龄加权平均值为249.3±4.1 Ma,结合野外地质关系,将新巴尔虎右旗韧性剪切带变形时代归属于中-晚三叠世。根据区域构造演化分析,认为其形成于蒙古-鄂霍茨克洋三叠纪晚期向额尔古纳地块南向俯冲的活动大陆边缘构造背景。通过区域韧性断裂对比,认为新巴尔虎右旗韧性剪切带为额尔古纳河-阿龙山NE向韧性变形域的南部延伸。新巴尔虎右旗韧性剪切带的发现为研究区域韧性变形构造及兴蒙造山带构造演化提供了基础资料。
The XinBarag Right Banner ductile shear zone was firstly found in the western part of northern Da Hinggan Mountains.According to the outcrop, the ductile shear zone should be an overthrust-sinistral strike slip.The latest geological body in the ductile shear zone is Early Triassic granodiorite and its southeast part is covered by Jurassic strata including the undeformed Early Jurassic Chaihe Formation.SHRIMP zircon U-Pb dating shows that the weighted age of the Early Triassic granodiorite is 249.3±4.1 Ma.Integrated with the outcrop geological characteristics of the study area, the authors hold that this large-scale ductile shear zone was formed under an active continental margin setting of the Mongolia-Okhotsk Ocean which subducted southward to the Eergu’Na Block during the Late-Middle Triassic period.A comprehensive analysis of the regional ductile faults shows that the XinBarag Right Banner ductile shear zone is the southward extension of the NE-trending Eergu’Na River-ALongshan ductile shear zone, and this new discovery provides basic data for the study of the regional ductile deformation structure and tectonic evolution in Xing’an-Mongolian Orogenic Belt.
作者
赵胜金
于海洋
申亮
周颖帅
柳志辉
张猛
杨海星
高利东
隋海涛
ZHAO Shengjin;YU Haiyang;SHEN Liang;ZHOU Yingshuai;LIU Zhihui;ZHANG Meng;YANG Haixing;GAO Lidong;SUI Haitao(No.10 Institute of Geological Exploration,Inner Mongolia Bureau of Geology and Mineral Resources,Chifeng 024005,Inner Mongolia,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Development and Research Center,China Geological Survey,Beijing 100037,China)
出处
《地质通报》
CAS
CSCD
北大核心
2020年第4期450-458,共9页
Geological Bulletin of China
基金
中国地质调查局项目《内蒙古1:5万巴雅尔吐胡硕、哈达营子、阿拉哈达、乙旦架拉嘎幅区域地质调查》(编号:DD20160048-15)
《内蒙古1:5万包尔呼吉塔拉等八幅区域地质调查》(编号:DD20160048-11)
《内蒙古1:5万乌音呼日勒庙、新巴尔虎右旗、霍特林呼都格、勃迪木呼都格幅区域地质矿产调查》(编号:12120114086201)。
关键词
大兴安岭北段
韧性剪切带
中-晚三叠世
兴蒙造山带
northern Da Hinggan Mountains
ductile shear zone
Middle Triassic
Xing’an-Mongolian Orogenic Belt
