新疆伊宁地块坎苏一带LA-ICP-MS锆石U-Pb年龄新资料及其地层归属  

New zircon U-Pb age data from LA-ICP-MS and its stratigraphic attribution in the Kansu area of Yining block,Xinjiang

作　　者：曾令高 郭文杰[1] 朱光辉 韩洪明 胡康强 李斌 ZENG Linggao;GUO Wenjie;ZHU Guanghui;HAN Hongming;HU Kangqiang;LI Bin(No.9 Geological Party,Bureau of Geo-exploration and Mineral Development of Xinjiang,Urumqi 830000,Xinjiang,China;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,Hubei,China;Northwest of Sichuan Geological Party,Bureau of Geo-exploration and Mineral Development of Sichuan,Mianyang 621000,Sichuan,China)

机构地区：[1]新疆地矿局第九地质大队,新疆乌鲁木齐830000 [2]中国地质大学地质过程与矿产资源国家重点实验室,湖北武汉430074 [3]四川地矿局川西北地质大队,四川绵阳621000

出　　处：《地质通报》2024年第9期1620-1635,共16页Geological Bulletin of China

基　　金：中央返还新疆两权价款项目《新疆新源县坎苏一带1∶5万K44E004024、K44E005024、K44E006024三幅区域地质调查》(编号:T15-1-LQ12)。

摘　　要：新疆伊宁地块坎苏一带原划泥盆纪坎苏组(变质)火山岩缺乏时代依据,前人或将其归为长城纪,或归为中—晚泥盆世,或归为晚石炭世,地层名称和区域对比也受此影响使用极混乱。在本区进行1∶5万区域地质调查时,对该套地层进行了层序恢复、原岩恢复,并对火山岩类进行了元素地球化学分析和LA-ICP-MS锆石U-Pb定年。研究认为,该套原划泥盆纪坎苏组(变质)火山岩中浅紫红色粗面岩和灰白色云母化英安岩锆石U-Pb年龄分别为315.6±1.6 Ma和306.6±1.2 Ma,侵入于火山岩中的正长花岗岩锆石U-Pb年龄为298.2±1.5 Ma,限定该套火山岩地质时代为晚石炭世。该套火山岩尽管遭受了较强烈的花岗岩类叠加变质和混染作用,但仍显示出大陆裂谷构造环境信息,总体与区域上的晚石炭世伊什基里克组可对比。据此,将原划泥盆纪坎苏组新厘定为晚石炭世伊什基里克组,为该套火山地层时代归属及区域对比提供了确凿证据。The original Devonian Kansu Formation(metamorphic) volcanic rocks in the Kansu area of Yining block was lack of chronological evidence,with era attribution belonging to the Precambrian Changcheng Period,the Middle-Late Devonian era,or the Late Carboniferous era,leading to confused stratigraphic names and regional correlation.The sequence restoration and proto-rock restoration,elemental geochemical analysis of volcanic rocks and LA-ICP-MS zircon U-Pb dating were carried out,on the basis of 1∶50000 regional geological survey in this area.The results show that the U-Pb ages of the light purplish trachyte and gray white mica-dacite zircons in the original Devonian Kansu Formation(metamorphic) volcanic rocks are 315.6±1.6 Ma and 306.6±1.2 Ma,respectively,and the U-Pb ages of the syenite zircon intrusions into the volcanic rocks are 298.2±1.5 Ma,which defined the geological age of the volcanic rocks as the Late Carboniferous Epoch.Although the volcanic rocks had been subjected to relatively strong granitoid superposition metamorphism and mixing,it still shows the tectonic environment information of continental rift,which is generally comparable to the Late Carboniferous Ishkirik Formation in the region.In view of this,the original Devonian Kansu Formation is newly determined to be the Late Carboniferous Ishkirik Formation,which provides conclusive evidence for the age attribution and regional correlation of volcanic strata.

关 键 词：坎苏组 地质地球化学特征 锆石U-PB年龄 伊什基里克组 伊宁地块 新疆 

分 类 号：P544[天文地球—构造地质学] P597.3[天文地球—地质学]