• 首页
  • 学报简介
  • 编委会
  • 投稿指南
  • 订阅指南
  • 过刊浏览
  • 在线投稿
  • 联系我们
  • 专家风采
  • English

本文将参加年度优秀论文评选,如果您觉得这篇文章很好,请投下您宝贵的一票,谢谢! 支持(26)   不支持(1)

新疆西准噶尔北部和布克赛尔蛇绿混杂岩的厘定及其洋盆闭合时代限定
投稿时间:2016-08-23  修订日期:2016-11-23  点此下载全文
引用本文:杨亚琦,赵磊,徐芹芹,郑荣国,牛宝贵.2018.新疆西准噶尔北部和布克赛尔蛇绿混杂岩的厘定及其洋盆闭合时代限定[J].地质学报,92(2):298-312
摘要点击次数: 450
全文下载次数: 340
作者单位E-mail
杨亚琦 中国地质科学院地质研究所北京100037 450218619@qq.com 
赵磊 中国地质科学院地质研究所北京100037 jleiz@163.com 
徐芹芹 中国地质科学院地质研究所北京100037  
郑荣国 中国地质科学院地质研究所北京100037  
牛宝贵 中国地质科学院地质研究所北京100037  
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目)
中文摘要:本文通过详细野外地质勘查,识别出新疆西准噶尔北部和布克赛尔蛇绿混杂岩中三种不同类型的岩石组合,即:由变质橄榄岩、辉长岩、辉绿岩墙、玄武岩和硅质岩组成的典型蛇绿岩单元;主要由洋岛玄武岩组成的大洋岛屿单元,在野外见与硅质岩、硅质泥岩和灰岩相伴产出;由变流纹岩组成的后碰撞期火山岩单元。蛇绿岩中的辉长岩和辉绿岩无明显Eu异常;(La/Yb)N值介于054~318之间,REE配分型式呈现微弱的轻稀土亏损或富集,兼具E MORB和N MORB的特征。洋岛玄武岩具有高的Al2O3(1366%~1583%)、TiO2(262%~315%)和Na2O+K2O(571%~7%),稀土元素含量高,显示明显的右倾模式,高场强元素Ti、Zr相对富集。变流纹岩具有高硅和钾,极低的MgO,MnO和CaO,不相容元素(K,Rb,Th,U,Pb)强烈富集,Sr,P,Ti显著亏损,Nb和Ta相对弱亏损的特点,形成于造山后伸展环境,其LA ICP MS锆石U Pb定年结果为435±2Ma。变流纹岩底垫贯穿或底垫侵入于蛇绿岩不同的单元组分中(橄榄岩、辉绿岩和玄武岩等),说明和布克赛尔蛇绿岩所代表的洋盆在早志留世晚期之前已经闭合。
中文关键词:蛇绿岩  洋岛玄武岩  流纹岩  西准噶尔  造山后伸展  侵位时代
 
Determination of the Hebukesaier Ophiolitic Mélange in the Northern Part of West Junggar and its Tectonic Implications
NameInstitution
YANG YaqiInstitute of Geology,Chinese Academy of Geological Sciences,Beijing,100037
ZHAO LeiInstitute of Geology,Chinese Academy of Geological Sciences,Beijing,100037
XU QinqinInstitute of Geology,Chinese Academy of Geological Sciences,Beijing,100037
ZHENG RongguoInstitute of Geology,Chinese Academy of Geological Sciences,Beijing,100037
NIU BaoguiInstitute of Geology,Chinese Academy of Geological Sciences,Beijing,100037
Abstract:Detailed field work helped identify threedifferent assemblages of rocks occurring in the Hebukesaier ophiolitic mélange in the northern region of West Junggar. They are typical ophiolite unit mainly consists of metamorphic peridotite, gabbro, diabasic dike, basalt and chert; ocean island unit mainly consists of OIB, which coexists closely with silicolit, silica mudstone and limestone; and post collision volcanic rock unit is mainly metarhyolite. Gabbro and diabase in ophiolite are characterized by slight enrichment or depletion in light rare earth elements and low (a/Yb)N ratios of 054~318, no obvious Eu anomalies, indicating that both are of E MORB and N MRB characteristic. The ocean island basalt shows relatively high contents of Al2O3 (366%~1583%), TiO2 (262%~315%) and Na2O+K2O (571%~7%), and displays an obvious right leaning pattern with a high content of rare earth elements. Metarhyolites exhibit relatively high SiO2 and K2O contents, and extremely low MgO, CaO and MnO contents, enrichment of incompatible elements (K, Rb, Th, U and Pb), obvious depletion of Sr, P and Ti, and weak depletions of Nb and Ta. Geochemical characteristics indicate that metarhyolites may be formed in a post orogenic extension setting. LA ICP MS U Pb 〖JP2〗dating on zircons from metarhyolite yieldes a weighted mean 206Pb/238U〖JP〗 age of 435±2 Ma. Metarhyolites cut through or intruded different units of ophiolite (peridotite, diabase and basalt), suggesting that the Paleo ocean basin of Hebukesaier ophiolite had been closed before late Early Silurian.
keywords:ophiolite  OIB  rhyolite  West Junggar  post orogenic extension  emplacement age
查看全文  查看/发表评论  下载PDF阅读器
您是第9620407位访问者  京ICP备05032737号-7  京公网 安备110102004559
版权所有:《地质学报(中文版)》
主管单位:中国科学技术协会 主办单位:中国地质学会
地  址: 北京阜成门外百万庄26号 邮编:100037 电话:010-68312410 E-mail: dizhixuebao@163.com
本系统由北京勤云科技发展有限公司设计