内蒙古锡林郭勒盟东部梅勒图组火山岩锆石U-Pb年龄、地球化学特征及其地质意义
投稿时间:2017-11-27  修订日期:2018-03-09  点此下载全文
引用本文:薛晓刚.内蒙古锡林郭勒盟东部梅勒图组火山岩锆石U-Pb年龄、地球化学特征及其地质意义[J].地质与勘探,2018,54(5):957-967
摘要点击次数: 127
全文下载次数: 106
作者单位E-mail
薛晓刚 长春工程学院 勘查与测绘工程学院吉林 长春 天津市地质调查研究院天津 516079667@qq.com 
基金项目:中国地质调查局项目(编号:1212011120696)和吉林省教育厅“十三五”科学研究规划项目(编号:JJKH20170520KJ )联合资助
中文摘要:内蒙古锡林郭勒盟东部扎布其尔沃布勒吉地区梅勒图组火山岩岩性主要为玄武安山岩、橄榄玄武岩、杏仁-气孔状玄武安山岩夹薄层凝灰岩。LA--ICP--MS锆石U—Pb测年数据显示,火山岩形成于137Ma-138Ma,为早白垩世中期。岩石地球化学数据分析表明:该组火山岩富钠,贫钾(Na2O/K2O比值为1.24~1.54),里特曼指数σ为2.18~3.57,属正常类型钙碱性系列岩石; 稀土元素富集(∑REE=327.40~534.77×10-6),LREE/HREE=10.37~17.42,轻、重稀土分馏明显(LaN/YbN=13.08~25.43);富集大离子亲石元素,高场强元素Ti、Nb、Hf亏损。MgO-FeO*-AL2O3和Th-Hf/3-Ta图解为造山带板内环境碱性玄武岩。其岩浆来源为富集地幔,形成于引张构造背景下。
中文关键词:梅勒图组 火山岩 锆石U-Pb年龄 地球化学 构造环境
 
Zircon U-Pb dating and geochemical characteristics of volcanic rocks in the Meiletu Formation of eastern Xilin Gol League, Inner Mongolia and their geological implications
Abstract:The volcanic rocks of the Meiletu Formation in eastern Xilin Gol League, Inner Mongolia are composed of basaltic andesite, olivine basalt and amygdaloidal-porous basalt andesite interbedded with thin tuff. The U-Pb dating ages of zircons by LA-ICP-MS range from 137 Ma to 138 Ma, showing that these rocks were formed in the Early Cretaceous. Geochemical study suggests that they are rich in sodium, while poor in potassium (Na2O/K2O=1.24~1.54). The Rittmann index is between 2.18 and 3.57, which belongs to the normal calc-alkaline series rocks. MnO-FeO*-Al2O3 and Th-Hf/3-Ta diagrams suggest basic basalts in orogenic and intraplate environments. The samples are characterized by high REE contents (∑REE=327.40×10-6~534.77×10-6), LREE/HREE=10.37~17.42, and significant fractionation between LREE and HREE (LaN/YbN=13.08~25.43). The trace element geochemistry is characterized by the enrichment of LILE such as Rb, Ba, K, and U and strong deficit of HFSE such as Nb, Ti and Hf. The MgO-FeO*-Al2O3 and Th-Hf/3-Ta diagrams suggest an alkaline basalt in orogenic and intraplate environments. Overall, their magma sources were derived from enriched mantle, forming in an extensional tectonic setting.
keywords:Meiletu Formation, volcanic rocks, zircon U-Pb age, geochemical characteristics, tectonic environment, Xilin Gol League, Inner Mongolia
查看全文  查看/发表评论  下载PDF阅读器