大兴安岭中南段查布其日上侏罗统玛尼吐组火山岩地质及年代学特征  

Geological and chronological characteristics of the Upper Jurassic Manitu Formation in Chabuqiri,central-south Great Hinggan Mountains

作　　者：陈显婷 董培培 李英杰 孟广安 林敏 王帅[6] 赵东芳 刘晶晶 刘志斌 CHEN Xianting;DONG Peipei;LI Yingjie;MENG Guang’an;LIN Min;WANG Shuai;ZHAO Dongfang;LIU Jingjing;LIU Zhibin(College of Earth Sciences,Hebei GEO University,Shijiazhuang,050031;Hebei Province Collaborative Innovation Center for Strategic Critical Mineral Research,Hebei GEO University,Shijiazhuang,050031;Innovation Base of Ore-forming Theory and Prospecting Technology of ophiolite Belt,Hebei University of Geosciences,Shijiazhuang,050031;Hebei Research Center of Geology and Mineral Resources,Shijiazhuang,050031;Fujian Institute of Geological Survey,Fuzhou,350013;China University of Geosciences,Beijing,100083)

机构地区：[1]河北地质大学地球科学学院,石家庄050031 [2]河北地质大学河北省战略性关键矿产研究协同创新中心,石家庄050031 [3]河北地质大学蛇绿岩带成矿理论与找矿技术创新基地,石家庄050031 [4]河北省地质矿产研究中心,石家庄050031 [5]福建省地质调查研究院,福州350013 [6]中国地质大学(北京),北京100083

出　　处：《地质论评》2024年第3期996-1012,共17页Geological Review

基　　金：科技基础资源调查专项(编号:2022FY101704);中国地质调查局项目(编号:1212011220460);河北地质大学学生科技基金资助项目(编号:KAZ202308)的成果。

摘　　要：通过1∶5万区域地质调查,运用“火山构造—岩性岩相—火山地层”三重填图方法,对大兴安岭中南段内蒙古查布其日地区上侏罗统玛尼吐组火山岩进行了系统的野外地质特征、岩石学、地球化学和锆石U-Pb年代学研究,分析玛尼吐组火山岩形成时代和构造背景。将内蒙古查布其日地区玛尼吐组划分为2个岩性段,一段为火山碎屑沉积岩和少量中性、中酸性火山碎屑岩,二段为中性火山熔岩、火山碎屑岩和少量火山碎屑沉积岩、酸性火山碎屑岩,构成一个完整的沉积喷发旋回;划分出爆发相(碎屑流堆积相、空落堆积相)、溢流相、火山通道相、喷发—沉积相等火山岩相,并圈出4个V级火山机构。获得查布其日玛尼吐组二段安山岩的LA-ICP-MS锆石U-Pb年龄为157.8±1.4 Ma,表明其形成时代为晚侏罗世。岩石地球化学特征为,玛尼吐组二段粗安岩的SiO_(2)为64.04%~65.40%,高Al_(2)O_(3)(16.02%~16.96%),岩石富碱(K_(2)O+Na_(2)O=8.07%~8.38%),低TFe_(2)O_(3)(1.38%~4.43%),贫TiO_(2)(0.6%~0.81%),A/CNK值介于1.02~1.12之间;稀土丰度总量ΣREE为177.60×10^(-6)~254.61×10^(-6),轻、重稀土分异较明显,(La/Yb)N=8.13~12.63,具弱负Eu异常(δEu=0.71~0.78);微量元素以富集大离子亲石元素(Rb、Ba、Th、U、K)和相对亏损高场强元素(Nb、Ta、P、Ti)为特征。主量元素、微量元素地球化学特征显示查布其日玛尼吐组二段粗安岩为钾玄质岩。研究区玛尼吐组火山岩岩浆来源于伸展作用触发先前俯冲板片释放流体交代的大陆岩石圈地幔发生部分熔融,且受地壳混染影响较小,可能形成于蒙古—鄂霍次克洋造山后的伸展构造环境。Based on 1∶50000 regional geological survey,the field geological characteristics,petrology,geochemistry and zircon U-Pb chronology of the volcanic rocks of the Upper Jurassic Manitu Formation in Chabuqiri area,Inner Mongolia,central-south Great Hinggan Mountains,were systematically studied by using the triple mapping method of“volcanic structural—litho—lithofacies and volcanic stratigraphy”.The Manitu Formation in Chabuqiri area of Inner Mongolia is divided into two lithologic members.The First Member consists of pyroclastic sedimentary rocks with a small amount of neutral and moderately acidic pyroclastic rocks,and the Second Member consists of neutral lava,pyroclastic rocks with a small amount of pyroclastic sedimentary rocks and acidic pyroclastic rocks,forming a complete sediment-eruption cycle.The volcanic facies are divided into eruptionsedimentary facies,excrete facies,clastic flow accumulation facies,void fall accumulation facies and volcanic channels,and fourⅤ-class volcanic edifices are outlined.The LA-ICP-MS U-Pb age of the zircons from the andesite in the Second Member of the Manitu Formation in Chabuqiri-manitu Formation is 157.8±1.4 Ma,indicating that it was formed in the Late Jurassic.The geochemical characteristics of the trachyandensite in the Second Member of the Manitu Formation are:SiO_(2)=64.04%~65.40%,high Al_(2)O_(3)(16.02%~16.96%),rich alkali(K_(2)O+Na_(2)O=8.07%~8.38%),low Fe_(2)O_(3)(3.12%~3.96%),poor TiO_(2)(0.6%~0.81%),A/CNK values between 1.02~1.12;theΣREE ranges from 177.6×10^(-6) to 254.6×10^(-6),with obvious differentiation between light and heavy rare earth,(La/Yb)N=8.13~12.63,and a weak negative Eu anomaly(δEu=0.71~0.78);the trace elements are characterized by rich large ion lithophile elements(Rb,Ba,Th,U,K)and relatively deficient high field strength elements(Nb,Ta,P,Ti).The geochemical characteristics of main elements and trace elements show that the trachyandensite of the Second Member of the Manitu Formation in Chabuqi area is shoshonitic series rock.The volc

关 键 词：上侏罗统 玛尼吐组 火山作用 LA-ICP-MS锆石U-PB定年 大兴安岭 蒙古—鄂霍次克洋 内蒙古查布其日 

分 类 号：P534.52[天文地球—古生物学与地层学] P588.14[天文地球—地质学]