%0 Journal Article
%T 40Ar-39Ar dating of the Mesozoic thrusting in Daqingshan thrust-nappe system, Inner Mongolia, China<br>内蒙古大青山逆冲推覆体系中生代逆冲构造活动的40Ar-39Ar定年
%A ZHANG JinJiang
%A QI GuoWei
%A GUO Lei
%A LIU Jiang
%A <br>张进江
%A 戚国伟
%A 郭磊
%A 刘江
%J 岩石学报
%D 2009
%I 
%X The northern Daqingshan orogen in Hohhot area is tectonically characterized by a northwest-directed thrust-nappe system, the Daqingshan thrust-nappe system, which consists of three east-northeast trending thrusts, three nappes and an autochthon. Higher-grade mylonite was formed at the bases of the hanging walls of the thrusts, while lower-grade phyllonite was produced on the top of the footwalls. Based on structural geological investigation and integrating macro-/micro-analyses of petrology and mineralogy, this study adopts 40Ar-39Ar dating method to constrain the deformation time of the Daqingshan thrust-nappe system. Three sericite samples of phyllonite give a 40Ar-39Ar age range of 120~119Ma and the other sample presents a peak age of 120Ma in the age-probability spectrum. Phyllonite was formed by a deformation at low temperatures and the fine-graded sericite in it was new-born syn-deformational mineral, therefore the sericite 40Ar-39Ar age can represent the deformation time very well. A weak-deformed granodiorite dike intruding the thrust indicates an emplacement in a late deformational stage, and its hornblende 40Ar-39Ar dating presents a lower-limitation age of 121Ma for the cooling of and the statistical peak age is also 119Ma. The lower-temperature phyllonite should be formed in a late stage of the deformation because higher-temperature mylonite developed at the bases of the nappes. Therefore, the thrusting of the Daqingshan thrust-nappe system must have been in its late deformational stage during the time form 120 to 119Ma.
%K Daqingshan thrust-nappe system
%K Thrusting
%K Phyllonite
%K 40Ar-39Ar dating<br>大青山逆冲推覆体系
%K 逆冲作用
%K 千糜岩
%K 40Ar-39Ar定年
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=E62459D214FD64A3C8082E4ED1ABABED5711027BBBDDD35B&cid=621CF755B1A341E5&jid=2013B5467E3054B1614CEC199353FCED&aid=6B5CF18DBAB29A6C86FFAD1391B9465F&yid=DE12191FBD62783C&vid=C5154311167311FE&iid=38B194292C032A66&sid=5568599C60D4BE87&eid=E6A0A363CA4FC5CF&journal_id=1000-0569&journal_name=岩石学报&referenced_num=0&reference_num=0