月球角砾岩Bechar 003、NWA 13788和NWA 11110中岩屑溯源研究

A study on the origin of protoliths of clasts in lunar breccia meteorites of Bechar 003,NWA 13788 and NWA 11110

月球角砾岩是月球陨石的代表性样品,含有多来源的岩屑,是揭示月球内-外动力演化历史的重要窗口。本文对Bechar 003、NWA 13788和NWA 11110月球陨石中的岩屑开展了岩相学、矿物学及地球化学分析,通过岩相、矿物成分、全岩主微量元素等岩石地化综合分析,旨在厘清这3块样品中岩屑的类型、来源与成因机制。结果表明,3块陨石内部的斜长辉长质冲击熔融岩屑、微斑熔融角砾岩屑、以及辉长质斜长岩屑的初始物质由均是月海玄武岩与月球高地岩石的混合物,不同初始物质成分的岩屑表明月表经历了冲击事件,并且冲击事件发生在月表的不同位置,冲击事件造成月球高地岩石与月海玄武岩或非月海溅射物的混合。

Lunar breccias are representative samples of lunar meteorites,containing rock clasts of multiple sources,and are served as important windows for understanding the internal and external evolution of the moon.The Bechar 003,NWA 13788,and NWA 11110 are recently discovered lunar meteorites,and they are classified as impact-melt breccias.In this study,we have conducted petrographic,mineralogical,and geochemical analyses of lithic clasts in these three lunar meteorites in order to clarify their types,sources,and formation mechanisms.Our comprehensive analyses of their characteristics of petrology,mineral compositions,and whole-rock major and trace elements indicate that the initial materials of anorthosite and gabbroimpact-melt debris,microporphyritic melt breccia debris,and gabbro-anorthosite debris in all three samples are all mixtures ofmare basalt and lunar highland rocks.Clasts with different compositions of initial materials in all three meteorites suggest that multiple impact events,occurred at different locations on the lunar surface,had resulted in the mixing of lunar highland rocks and mare basalts or non-mare sputtering materials.