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ID:46534234
大小:1.48 MB
页数:10页
时间:2019-11-25
《论东川地区前震旦系地层层序来自锆石SHRIMP及LA-ICP-MS测年的证据》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、2011年9月,第17卷,第3期,452—461页高校地质学报September2011,Vo1.17,No.3,P.452-461GeologicalJournalofChinaUniversities论东川地区前震旦系地层层序来自锆石SHRIMP及LA—ICP—MS测年的证据朱华平,范文玉,周邦国,王生伟,罗茂金,廖震文,郭阳成都地质矿产研究所,成都610081摘要:对东川地区的因民组内部辉绿岩体(Tw1)、洒海沟组熔结凝灰岩(TW2)和平顶山组沉积砾岩(TW3)进行了锆石U—Pb年龄测定。结果
2、表明,Tw1获得上交点年龄为(1667±13)Ma,指示因民组内部辉绿岩体侵入时代为中元卉代早期。TW2获得两组年龄,其中。Pb/Pb~II权平均年龄(2285+12/一l1)Ma,指示火山岩形成时代为古元古代;上交点年龄为(2742±48)Ma,表明东川I地区存在着一套更老的岩石地层。Tw3获得最年轻一组碎屑锆石的”Pb/Ph加权平均年龄为(1838±10)Ma,它代表平顶山组最大的沉积时限。基于以上定年数据,笔者认为东川I地区的前震旦系地层层序由老至新分别为:洒海沟组、望厂组、菜园湾组、平顶山组
3、、因民组、落雪组、黑山组、青龙山组、大营盘组。关键词:锆石SHRIMP及LA—ICP—MS年龄;地层层序;前震旦系;东川地区中图分类号:P539.2;P597文献标识码:A文章编号:1006—7493(2011)03—0452—10AssessingPrecambrianStratigraphicSequenceofDongchuanArea:EvidencefromZirconSHRIMPandLA-ICP-MSDatingZHUHua—ping,FANWen—yu,ZHOUBang—guo,WA
4、NGSheng—weLUOMao-jin,LIAOZhen—wen,GUOYangChengduInstituteofGeologyandMineralResources,Chengdu610081,ChinaAbstract:Theauthorsgotaseries0±zirconU—Pbagesfor3samplesinDongchuanareaYunnanprovince:thediabase(TW1)cuttingYinmingFormation,theignimbrite(TW2)ofSa
5、haiguoFormation,andthesedimentaryconglomerate(Tw3)ofPingdingshanFormation.TheSHRIMPzirconU-PbdatingforTW1yieldedanupperintersectionageof(1667±13)Ma,whichindicatesthetimingofdiabaseintrusionactivityinMesoproterozoic.TheSHRIMPzirconU-PbdatingforTW2showed
6、twoages:aneverageweightedageof(2285±11)MacanheconsideredastheeruptiontimingoflavainPaleoproterozoic。andtheupperintersectionageof(2742±48)MaindicatesthataseriesofolderrocksmightexistintheDongchuanarea.TheLA—ICP—MSdatingforsampleTW3yieldedanyoungestconco
7、rdantageof(1838±10)Ma,whichconstrainedtheoldestsedimentationageofthePingdingshanFormation.Basedonthesedatingresults,thePrecambrianstratigraphicsequencefittingtheDongchuanareafromtheolderrocksupwardsisasfollows:SahaiguoFormation,WangchangFormation,Caiyu
8、anwanFormation,PingdishanFormation,YinmingForamation,LuoxueFormation,HeisanFormation,QinglongsanFormationandDayingpangFormation.Keywords:Dongchuanarea;ZirconU—Pbdating;stratigraphicsequence;PrecambrianC0rresp0ndingauthor:FanWenyu,Senior
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