摘要
Howardite-Eucrite-Diogenite(HED)族陨石是地球上目前发现数量最多的无球粒陨石类型,已发现的HED族陨石主要来自于南极和非洲西北部的沙漠,本研究的HED族陨石国际命名为Yiwu 001,发现于中国新疆维吾尔自治区伊吾县境内。系统的矿物学和岩石学研究显示,该陨石属于单矿物碎屑角砾岩Eucrite,主要矿物为易变辉石(38%)、普通辉石(8%)和斜长石(46%),副矿物主要为二氧化硅、陨硫铁、铬铁矿、钛铁矿。根据主要矿物的粒径,对该陨石开展了区域划分:粗粒、细粒和极细粒,辉石对应的粒径均值分别为550μm、100μm和60μm。粗粒和部分细粒区域具次辉绿结构,细粒和极细粒区域发育麻粒结构。陨石中细粒玄武岩包裹着以椭球体为主的粗粒和拉长的极细粒玄武岩,极细粒玄武岩呈定向构造。Yiwu 001陨石原岩可能为内含粗粒玄武岩捕虏体的玄武岩,定向构造指示可能发生过近静态的部分熔融。该陨石在晚期经历了复杂的热变质作用,为5型变质类型,主要表现在出溶辉石条带、麻粒结构和三联点结构。
Howardite-Eucrite-Diogenite(HED) meteorites, mainly collected in Antarctica and the hot desert of Northwest Africa, are the most abundant achondrite at present. Yiwu 001 reported in this research is an HED meteorite collected in the Yiwu County, Xinjiang Uygur Autonomous Region, China. The systematic petrological and mineralogical characteristics of Yiwu 001 suggest that this meteorite belongs to monomict eucrite. Mineralogically, Yiwu 001 is mainly composed of pigeonite(38%), augite(8%) and plagioclase(46%), and the accessory minerals include silica, troilite, chromite and ilmenite. Based on the grain size of the main minerals, Yiwu 001 is divided into three areas as coarse-grained, fine-grained and ultrafine-grained areas, and the average grain size of pyroxene in which is 550 μm, 100 μm and 60 μm, respectively. Texturally, the coarse-grained and partial fine-grained areas develop subophitic texture, in addition, the ultrafine-grained and the fine-grained areas are characterized by granulitic texture. The coarse-grained basalt(mainly ellipsoid) and elongated ultrafine-grained basalt with oriented structure are surrounded by fine-grained basalt matrix. Yiwu 001 with complex post-thermal metamorphism should be a basalt containing a small amount of coarse-grained basaltic xenoliths, and the oriented structure may indicate that Yiwu 001 has undergone near-static partial melting. Yiwu 001 is classified as Type-5 thermal metamorphism based on the exsolution lamella, granulitic texture andtriple junctions.
作者
高天静
冯彩霞
宋光明
刘燊
李世杰
GAO Tianjing;FENG Caixia;SONG Guangming;LIU Shen;LI Shijie(State Key Laboratory of Continental Dynamics,De partment of Geology,Northwest University,Xian,Shannxi 710069,China;Beijing Institute of Spacecra ft Environment Engineering,Beijing 100094,China;Guangxi Hidden Mineral Exploralion Center,College of Earth Sciences,Guilin University of Technology,Guilin,Guangxi 541004,China;Instilute of Geochemistry,Chinese Academy of Sciences,Guiyang Guizhou 550081,China)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2021年第9期2901-2908,共8页
Acta Geologica Sinica
基金
西部之光项目A(中国沙漠陨石居地年龄的测定)
民用航天预研项目(编号D020304)联合资助的成果。
