鄂北耿集-板桥地区新元古代变火山岩系地层归属——来自锆石U-Pb测年、Hf同位素的证据  

Attribution of Neoproterozoic Meta-Volcanic Series in Gengji Banqiao Area,Northern Hubei Province:Evidence from Zircon U Pb Dating and Hf Isotopes

作　　者：苑东洋 石威 刘德民[4] 黄天统 徐龙生 陈超[4,5] 孔令耀 Yuan Dongyang;Shi Wei;Liu Demin;Huang Tiantong;Xu Longsheng;Chen Chao;Kong Lingyao(Changsha Uranium Geology Research Institute,Changsha 410007,China;Hunan Engineering Technology Research Center for Evaluation and Comprehensive Utilization of Associated Radioactive Mineral Resources,Changsha 410007,China;Third Geological Brigade of Hubei Geological Bureau,Huanggang 438000,Hubei,China;School of Earth Sciences,China University of Geosciences,Wuhan 430074,China;Hubei Geological Survey,Wuhan 430034,China)

机构地区：[1]核工业二三〇研究所,长沙410007 [2]湖南省伴生放射性矿产资源评价与综合利用工程技术研究中心,长沙410007 [3]湖北省地质局第三地质大队,湖北黄冈438000 [4]中国地质大学地球科学学院,武汉430074 [5]湖北省地质调查院,武汉430034

出　　处：《吉林大学学报（地球科学版）》2024年第2期516-530,共15页Journal of Jilin University：Earth Science Edition

基　　金：中国地质调查局项目(DD20221645)。

摘　　要：扬子克拉通北缘、鄂北枣阳市耿集-板桥地区震旦系—奥陶系中相间出露两套变火山岩系,其地层归属存在武当群和花山群的争议且长期缺乏深入研究。耿集-板桥地区野外调查、变火山岩系LA-ICPMS锆石U-Pb测年、Lu-Hf同位素分析结果表明:耿集地区变火山岩系主要为浅灰色、灰白色变酸性含砾晶屑岩屑凝灰岩、晶屑凝灰岩、玻屑凝灰岩、粉砂岩,与打鼓石群硅质条带叠层石白云岩共生,其中变酸性晶屑凝灰岩锆石年龄为821.7 Ma、ε_(Hf)(t)值为-2.44~9.70,其可能是扬子克拉通前南华纪基底青白口系花山群组成部分;板桥地区变火山岩系主要由灰白色变酸性晶屑岩屑凝灰岩、火山凝灰岩、酸性火山岩、粉砂岩组成,内部发育大量基性侵入岩,其中变酸性火山岩锆石年龄为741.2 Ma,ε_(Hf)(t)值为4.62~9.56,其应归属为南秦岭造山带南华系武当群,可能是印支期逆冲到扬子克拉通盖层上的残块。There are two sets of meta-volcanic series scattered among the Sinian Ordovician in Gengji and Banqiao area of Zaoyang City,northern Hubei Province,Northern Yangtze craton.Their attribution is disputed by the Wudang Group and Huashan Group,and has lacked in-depth research for a long time.Through systematic field investigation,LA ICP MS zircon U Pb dating and Lu Hf isotopic analysis,we propose that the meta-volcanic series in the Gengji area were mainly light gray and grayish white metamorphic acidic pebbly pyroclastic tuff,crystalline tuff,vitroclastic tuff and siltstone,associated with the siliceous striated stromatolite dolomite of the Dagushi Group.The zircon age for the metamorphic pyroclastic tuff from Gengji is 821.7 Ma with zircon ε_(Hf)(t)values of-2.44-9.70,indicating that they may be part of the Huashan Group in the Northern Yangtze craton.However,the meta-volcanic series in the Banqiao area were mainly composed of grainy and white metamorphic acid clastic rock tuff,volcanic tuff,acid volcanic rock and siltstone,and associated with a large number of basic intrusive rocks.The zircon age of the metamorphic acid volcanic rocks from Banqiao is 741.2 Ma with zircon ε_(Hf)(t)values of 4.62-9.56,indicating they belong to the Wudang Group in the South Qinling orogen,and may be a remnant of the thrust nappe during Indosinian.

关 键 词：扬子克拉通 新元古代 花山群 武当群 锆石U-PB测年 LU-HF同位素 

分 类 号：P588.1[天文地球—岩石学] P597[天文地球—地质学]