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哀牢山构造带南段风别山霏细斑岩地球化学特征及其锆石U-Pb年代学研究
投稿时间:2017-09-09  修订日期:2018-08-21  点此下载全文
引用本文:孙崇波,李忠权,陈晓东,谢万洪,王道永.2018.哀牢山构造带南段风别山霏细斑岩地球化学特征及其锆石U-Pb年代学研究[J].地质论评,64(5):1251-1262
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作者单位E-mail
孙崇波 1) 国土资源部构造成矿成藏重点实验室(成都理工大学)、油气藏地质及开发工程国家重点实验室(成都理工大学)成都 6100592) 四川冶金地质勘查局水文工程大队成都 611730 1315333036@qq.com 
李忠权 1) 国土资源部构造成矿成藏重点实验室(成都理工大学)、油气藏地质及开发工程国家重点实验室(成都理工大学)成都 610059  
陈晓东 1) 国土资源部构造成矿成藏重点实验室(成都理工大学)、油气藏地质及开发工程国家重点实验室(成都理工大学)成都 6100592) 四川冶金地质勘查局水文工程大队成都 611730  
谢万洪 2) 四川冶金地质勘查局水文工程大队成都 611730  
王道永 1) 国土资源部构造成矿成藏重点实验室(成都理工大学)、油气藏地质及开发工程国家重点实验室(成都理工大学)成都 610059  
基金项目:本文为中国地质调查局“西南三江成矿带南段基础地质调查”(编号:1212010880406、1212011120582)的成果。
中文摘要:本文对云南省墨江县风别山霏细斑岩进行了锆石U-Pb年代学、岩石地球化学分析。LA-ICP-MS锆石U-Pb测年显示,风别山霏细斑岩年龄为266.1±1.5Ma,形成于中二叠世晚期。岩石地球化学显示,风别山霏细斑岩SiO2含量为75.04% ~ 81.88%,全碱(Na2O+K2O)含量为7.07% ~ 9.52%;岩石富集轻稀土,负铕异常明显(δEu:0.04 ~ 0.08),相对富集Th、U,相对贫化Sr、Ta、Cr、Au。通过图解显示风别山霏细斑岩形成于碰撞期后板内构造环境,说明哀牢山构造带的古特提斯支洋或弧后盆地在中二叠世晚期266.1 ± 1.5Ma可能已经闭合。
中文关键词:霏细斑岩  锆石 U-Pb年代学  岩石地球化学  造山期后花岗岩
 
Petrogeochemistry and Zircon U-Pb Chronology of the Fengbieshan Felsophyre in Southern Section of Ailaoshan Tectonic Belt
NameInstitution
SUN Chongbo1) Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation of Ministry of Land and Resources (Chengdu University of Technology), State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Chengdu University of Technology), Chengdu, 610059;2) Hydro-Engineering Party of Sichuan Metallurgical Geology and Exploration Bureau, Chengdu, 611730
LI Zhongquan1) Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation of Ministry of Land and Resources (Chengdu University of Technology), State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Chengdu University of Technology), Chengdu, 610059
CHEN Xiaodong1) Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation of Ministry of Land and Resources (Chengdu University of Technology), State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Chengdu University of Technology), Chengdu, 610059;2) Hydro-Engineering Party of Sichuan Metallurgical Geology and Exploration Bureau, Chengdu, 611730
XIE Wanhong2) Hydro-Engineering Party of Sichuan Metallurgical Geology and Exploration Bureau, Chengdu, 611730
WANG Daoyong1) Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation of Ministry of Land and Resources (Chengdu University of Technology), State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Chengdu University of Technology), Chengdu, 610059
Abstract:Objectives:The Ailaoshan tectonic belt is situated at the contact site of Tethys—Himalaya tectonic region and coastal Pacific tectonic region. At present, it is still controversial that whether Jinshajiang—Ailaoshan tectonic belt exists paleotethys ramose ocean basin or not in late Paleozoic era. In regard to this dispute, we focus on the study of petrogeochemistry and zircon U Pb chronology of the Fengbieshan felsophyre in Yunnan to evaluate geological evolution in late Paleozoic era in southern section of Ailaoshan tectonic belt.Methods:Factitious heavy fraction was conducted to select zircons from the fresh sample of PM3005Z and well crystallized, crackless, and transparent zircons were selected under the microscope,then photos of zircons were taken under reflected light and transmission light and CL image. The U-Pb isotope analysis was carried out at the laser probe of LA-ICP-MS Elan6100DRC in isotope geochemistry national key laboratory of Guangzhou Geochemical Institute. The analysis of major element compositions was completed with fluorescent spectrometer (XRE) of Rigaku RIX 2000. The analysis of trace element compositions was performed with inductively coupled plasma source mass spectrometer (LA-ICP-MS) of Perkin Elmer Sciex ELAN 6000.Results:LA-ICP-MS zircon U Pb dating results show that the Fengbieshan granodiorite formed in the Late Permian (263.6 ±2.4Ma). The Fengbieshan granodiorite is characterized by SiO2 62.10%~63.09%, alkali (Na2O+K2O) 6.28%~7.21%, and Na2O>K2O. Moreover, it is enriched in LREE and Sc, Hf, and depleted in Sr, Zr, Th, U , with negative Eu anomalies ( δEu:0.84~1.32 ).Conclusions:According to the analysis data, we consider that the Fengbieshan granodiorite formed in the tectonic environment of island arc—continent or continental—arc collision, indicating that the branch of Paleo Tethys Ocean or arc basin in Ailaoshan tectonic belt may have been closed in the Late Permian ( 263.6 ± 2.4Ma ).
keywords:felsophyre  zircon U-Pb chronology  petrogeochemistry  post-orogenic granite
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