【作者】 张玉涛； 张连昌； 英基丰； 周新华； 王非； 侯泉林； 刘庆；

【Author】 ZHANG YuTao,ZHANG LianChang,YING JiFeng,ZHOU XinHua,WANG Fei,HOU QuanLin and LIU Qing 1.Key laboratory of Mineral Resources,Institute of Geology and Geophysics,CAS,Beijing 100029,China 2.State key laboratory of lithospheric evolution,Institute of Geology and Geophysics,CAS,Beijing 100029,China 3.Graduate university of Chinese Academy of Sciences,Beijing 100039,China

【机构】 中国科学院地质与地球物理研究所矿产资源研究重点实验室； 中国科学院研究生院； 岩石圈演化国家重点实验室中国科学院地质与地球物理研究所；

【摘要】 大兴安岭北段塔河地区分布有大面积的晚中生代火山岩,主要岩石类型为玄武岩、玄武安山岩、玄武质粗面安山岩和粗面安山岩,并且以碱性岩石为主。SiO₂含量为47.34%～58.03%,K₂O含量为1.25%～3.44%。富集大离子亲石元素（LILE）如Rb和Ba,δEu为0.71～1.14,高场强元素（HFSE）如Nb和Ta在原始地幔标准化图解上有强烈的负异常。从同位素组成特点来看,(⁸⁷Sr/⁸⁶Sr)_i变化于0.705472和0.707821之间,ε_Nd（t）为-6.81～0.58,与EMI靠近并有向EMII延伸的趋势。²⁰⁶Pb/²⁰⁴Pb为18.1497～18.5394,²⁰⁷Pb/²⁰⁴Pb为15.4886～15.5390,²⁰⁸Pb/²⁰⁴Pb为37.7608～38.3441,位于EMI和EMII之间,并也有向EMII变化的趋势。综合考虑塔河火山岩的特点并结合他人研究成果,本文认为塔河地区的这套火山岩形成于富集的大陆岩石圈地幔的重熔及其结晶分异作用。更多还原

【Abstract】 There are abundant late Mesozoic volcanic rocks in Tahe,north Da Hinggan Mountain.The main rock types of these volcanic rocks are basalt、basaltic andesite、basaltic trachyandesite and trachyandesite and the alkalic ones are dominant.They have a SiO₂ range of 47.34%～58.03%and their K₂O content changes between 1.25%and 3.44%.These rocks are all enriched in LILE such as Rb and Ba withδEu changes from 0.71 to 1.14.HFSE such as Nb and Ta have a conspicuous trough in the primitive mantle normalized spider diagram.From the isotopes point,(⁸⁷Sr/⁸⁶Sr)_i has a range of 0.705472 to 0.707821 andε_Nd（t） changes from -6.81 to 0.58,which are near the EMI area and have a trend to EMII area.As for lead isotopes,²⁰⁶Pb/²⁰⁴Pb is 18.1497 to 18.5394,²⁰⁷Pb/²⁰⁴Pb is 15.4886 to 15.5390,²⁰⁸Pb/²⁰⁴Pb is 37.7608 to 38.3441,which are between EMI and EMII areas and also have a trend to EMII area.Judging from the above characteristics of the Tahe Mesozoic volcanic rocks and other people’s studies,we conclude that this suit of late Mesozoic volcanic rocks in Tahe originated from the remelting and fractionation of metasomatized enriched subcontinental lithospheric mantle.更多还原