大兴安岭中段东福岩体锆石U-Pb年龄、地球化学特征及构造背景  

An analysis of Zircon U-Pb age,geochemistry and tectonic setting of Dongfu pluton in Tuquan,middle Da Hinggan Mountains

作　　者：杜继宇[1,2] 宋维民[1] 杨佳林[1,3] 陶楠 庞雪娇[1] 杨扬[4] DU Jiyu;SONG Weimin;YANG Jialin;TAO Nan;PANG Xuejiao;YANG Yang(Shenyang Center of Geological Survey,CGS,Shenyang 110034,Liaoning,China;College of Earth Sciences,Jilin University,Changchun 130061,Jilin,China;Institute of Geology,Chinese Academy of Geological Science,Beijing 100037,China;School of Prospecting&Surveying Engineering,Changchun Institute of Technology,Changchun 130021,Jilin,China)

机构地区：[1]中国地质调查局沈阳地质调查中心,辽宁沈阳110034 [2]吉林大学地球科学学院,吉林长春130061 [3]中国地质科学院地质研究所,北京100037 [4]长春工程学院勘查与测绘工程学院,吉林长春130021

出　　处：《地质通报》2020年第6期919-928,共10页Geological Bulletin of China

基　　金：中国地质调查局项目《内蒙古15万前他克吐等五幅区域地质矿产调查》(编号:1212011220425);《内蒙古15万必鲁台等四幅地质矿产综合调查》(编号:12120115031101);《内蒙古15万老房身等五幅区域地质调查》(编号:DD20190039-06);《地质调查综合智能编图系统与应用》(编号:DD20190415);《国家地质数据库建设与整合》(编号:DD20160351)。

摘　　要：对突泉地区东福岩体二长岩进行了LA-ICP-MS锆石U-Pb年代学和地球化学研究,探讨其形成构造背景。结果显示,二长岩形成于161.8±1.1 Ma,时代为晚侏罗世早期;二长岩具有弱负Eu异常、富大离子亲石元素、贫高场强元素特征,原始岩浆应来自地壳物质的部分熔融;较高的Sr含量表明源区有少量斜长石残留,轻稀土元素富集、重稀土元素亏损暗示源区富集重稀土元素矿物(如石榴子石)的残留,二者共同揭示二长岩形成于中-高压环境,是加厚陆壳坍塌或拆沉到一定阶段部分熔融的产物。结合区域资料,认为该区晚侏罗世二长岩的形成与蒙古-鄂霍茨克缝合带演化至后碰撞阶段构造环境有关,蒙古-鄂霍茨克洋南西段在晚侏罗世早期已闭合。LA-ICP-MS zircon U-Pb geochronology and geochemistry of the monzonite in Dongfu pluton of Tuquan area was studied to explore the tectonic background of its formation.The results show that the monzonite was formed in Late Jurassic(161.8±1.1 Ma).The monzonite displays slightly negative Eu anomalies,enrichment of LILEs and depletion of HFSEs,suggesting that its primitive magma was derived from partial melting of the crust.High content of Sr shows the existence of a small amount of residual plagioclase in the source region.The enrichment of LREEs and depletion of HREEs suggest that the minerals such as pomegranate were enriched in HREEs in the source region.The residues of plagioclase and pomegranate reveal that the monzonites were formed in the environment with medium-high pressure,and were products of the partial melting of the thickened crust which delaminated or collapsed to a certain extent.Combined with regional geology,the authors hold that the formation of the monzonites was related to the post-collisional tectonic environment of the evolution in Mongolia-Okhotsk suture zone,and the southwestern part of the Mongolia-Okhotsk Ocean was closed in Late Jurassic.

关 键 词：突泉地区 地球化学 晚中生代 二长岩 蒙古-鄂霍茨克洋 后碰撞阶段 

分 类 号：P588.122[天文地球—岩石学] P597.3[天文地球—地质学]