新疆东部博格达山北侧石炭系碎屑锆石U-Pb定年及其地质意义  

U-Pb Dating of Carboniferous Sandstone Detrital Zircon from the North of the Bogda Mountains,Eastern Xinjiang,and Its Geological Significances

作　　者：陈登超[1,2] 赵省民[2] 邓坚[2] 

机构地区：[1]中国石化胜利油田有限公司地质研究院,山东东营257015 [2]中国地质科学院矿产与资源研究所,北京100037

出　　处：《地质学报》2010年第12期1770-1780,共11页Acta Geologica Sinica

基　　金：中国地质大调查项目(编号1212010633601)资助成果

摘　　要：本文应用LA-ICPMS锆石U-Pb定年方法,对博格达山北侧原石炭系沙雷赛尔克组及沙玛尔沙依组开展了碎屑锆石U-Pb年代学研究。测年结果显示沙雷赛尔克组碎屑锆石表面年龄值分布较宽(298～2215Ma),主要集中在298～344Ma,主峰值年龄为305Ma,次要峰值为501～538Ma,并见有一粒1331Ma及两粒2146Ma、2215Ma的碎屑锆石;沙玛尔沙依组碎屑锆石表面年龄分布较窄(280～523Ma)且相对集中(299～358Ma),主峰值年龄为345Ma,次要峰值年龄为428～450Ma及507～523Ma。通过样品岩石学特征、碎屑锆石Th、U含量、CL组构特征及区域地质资料分析,初步获得以下认识:①博格达山北侧原定义为石炭纪地层的沉积时代应为早石炭世—早二叠世,其中奇尔古斯套群时代为早石炭世晚期—晚石炭世早期,居里得能组—扬布拉克组时代为晚石炭世中期及晚期,沙玛尔沙依组时代为早二叠世早期,缪林托凯陶山组沉积时代及其与沙玛尔沙依组的关系尚有待于进一步研究;②沙雷赛尔克组及沙玛尔沙依组砂岩主要来自于准噶尔盆地,主要物质供给区为区内略早于或与其同时代沉积的石炭纪地层;③博格达晚古生代大陆裂谷在早石炭世已形成,晚石炭世开始衰退,并发生两次弱造山作用,中二叠世夏子街期最终闭合。This paper studied the age distribution of detrital zircons of sandstone in Shaleisaierke Formation and Shamaershayi Formation of Carboniferous System using LA-ICPMS U-Pb isotopic age of zircons.The results show that the detrital zircons of Shaleisaierke Formation has a wide range of zircon age from 298Ma to 2215Ma,and distributes mainly between 298Ma and 344Ma,with a peak at 305Ma and a second peak at between 501～538Ma.In addition,there is also one detrital zircon with an age of 1354Ma,and other two detrital zircons with ages of 2146Ma.and 2215Ma.The Shamaershayi Formation has a narrow（280 ～523Ma）and centralized age distribution（299～358Ma）,with a dominant peak at 345Ma,and some lesser peaks between 428～450Ma and 507～523Ma,respectively.Based on the petrology of samples,the contents of Th U,CL image of dated zircon,in combination with regional geology analysis,the following conclusions have been achieved.（1）The age of the strata in the northern part of Bogda mountain,which was originally defined to be Carboniferous period,should be early carboniferous to early Permian;the age of the Qisiguertao Group is later Early Carboniferous to early Late Carboniferous.Julideneng Formation～Yangbulake Formation and Shamaershayi Formation should be middle or later middle Carboniferous to early Late Carboniferous and early Early Permian respectively.（2）The sandstones of the Shaleisaierke Formation and Shamaershayi Formation come from the eastern of Junggar basin,with the main source of the sandstone forming earlier than or the same age as the Carboniferous stratum in the study area.（3）The Late Paleozoic Bogda rift started in Early carboniferous,and began to decay in Late carboniferous with two weak orogenies,then finally declined during the Xiazihe Stage of middle Permian.

关 键 词：准噶尔盆地 博格达山 石炭系 碎屑锆石 LA-ICPMSU-Pb定年 

分 类 号：P597.3[天文地球—地球化学]