摘要
大兴安岭北段根河地区出露一套玄武岩。为明确该套玄武岩的岩石成因、地层时代归属及其构造背景,本文对该玄武岩进行了锆石LA-ICP-MS U-Pb年代学和岩石地球化学研究。锆石U-Pb测定结果表明,根河地区玄武岩形成于早白垩世(142. 0±2. 1 Ma),将其暂归置于玛尼吐组,并非前人认为的下石炭统莫尔根河组。岩石地球化学特征表明,该玄武岩富钠低钾,属碱性系列,稀土元素总量(ΣREE)较低(91. 50×10-6～108. 57×10-6),轻重稀土分馏较明显((La/Yb)N=10. 82～13. 49),轻稀土元素和K、Rb、Ba、Sr等大离子亲石元素相对富集,亏损Th、U、Hf、Ti、Nb、Ta等高场强元素和重稀土元素。综合本次研究和区域构造演化,认为根河地区早白垩世玄武岩来源于富集的岩石圈地幔板内碱性玄武岩,形成于蒙古-鄂霍茨克洋闭合后的岩石圈伸展背景。
A set of basalt is exposed in the Genhe area,northern Great Xing an Range.The objective of this work is to clarify its petrogenesis,stratigraphic age and tectonic setting by virtue of zircon LA-ICP-MS U-Pb geochronology and petrochemistry.The results of zircon U-Pb measurement indicate that this basalt formed in the Early Cretaceous(142.0±2.1 Ma),temporarily placed in the Manitu group,rather than Lower Carboniferous Mo ergenhe group suggested in previous research.The geochemical characteristics of the rock indicate that the basalt is rich in sodium and low potassium,which belongs to the alkaline series.The total amount of rare earth elements(ΣREE)is low(91.50×10-6~108.57×10-6),and the light and heavy rare earth fractionation is obvious(La/Yb)N=10.82~13.49),light rare earth elements and K,Rb,Ba,Sr and other large ion lithophile elements are relatively enriched,depleted in Th,U,Hf,Ti,Nb,Ta and other high field strength elements and heavy rare earth elements.Combining this study and regional tectonic evolution,it is suggested that the Early Cretaceous basalt in the Genhe area is an intraplate alkaline basalt derived from the enriched lithospheric mantle,which formed in a setting of lithospheric extension after the closure of the Mongolia-Okhotsk ocean.
作者
吴涛涛
周永恒
陈聪
刘凯
鲍庆中
吴大天
柴璐
WU Tao-tao;ZHOU Yong-heng;CHEN Cong;LIU Kai;BAO Qing-zhong;WU Da-tian;CHAI Lu(Shenyang Geological Survey Center,China Geological Survey,Shenyang,Liaoning 110034)
出处
《地质与勘探》
CAS
CSCD
北大核心
2018年第6期1270-1281,共12页
Geology and Exploration
基金
中国地质调查局项目(编号:DD20160104和DD20160047)资助
关键词
板内碱性玄武岩
岩石圈伸展
玛尼吐组
根河地区
大兴安岭北段
within plate alkali basalts
lithosphere extension
Manitu Formation
Genhe area
north part of the Great Xing an Range
作者简介
吴涛涛(1988年-),男,硕士,工程师,主要从事基础地质调查及矿床研究方面工作。E-mail:wutaotao@mail.cgs.gov.cn;[通讯作者]周永恒(1980年-),男,博士,高级工程师,主要从事东北亚地区矿产资源潜力评价工作。E-mail:zhouyongheng@mail.cgs.gov.cn。
