月球陨石: 月球的物质组成及其演化历史的见证

月球陨石是遭受小行星物质撞击溅飞出来的月球岩石样品，是研究月球物质成分和演化历史的重要对象。自1979年发现和确认了第一块月球陨石（ALHA 81005）之后，至今已收集到136块月球陨石样品。虽然Apollo计划和Luna计划回收了382kg月球样品，但由于飞船登陆采样位置有限，月球陨石对了解月球的物质组成和成因演化提供了重要补充。除了少量具有结晶结构的岩石类型以外，大部分月球陨石为碎屑岩，这些碎屑岩主要有三类：高地斜长角砾岩、月海玄武质角砾岩、和高地斜长质-月海玄武质混合角砾岩。根据岩性分析，尤其是岩屑，月球陨石中存在斜长岩、玄武岩、辉长岩、橄长岩、苏长岩、KREEP岩。在月球陨石中逐渐发现了不少克里普岩组分，其中SaU169中VHK的富KREEP成分可能代表了月球中的原始富KREEP岩浆源，这为探索月球中KREEP成因提供重要信息。据研究，现已发现了6对溅射成对月球陨石，同时，发现了9个可能的月球陨石来源区域。后成合晶现象的发现对月球表面冲击变质作用研究具有重要的意义。此外，月球陨石同位素年龄和稀有气体成分研究不但获得了月球岩石结晶和月壳形成过程，同时获得了月球表面的冲击变质历史。

LUNAR METEORITES: WITNESSES TO THE MOON’S COMPOSITION AND EVOLUTION

Lunar meteorites are the rock sample of the Moon that were experienced the shock event by asteroids and splashed away from it. Since the first lunar meteorites (ALHA 81005) was discovered and identified in 1979, there is the collection of 136 lunar meteorites. The Apollo and Luna projects returned 382 kg lunar samples, because the collection sites are very limited, so lunar meteorites are still the important supplementary to get insight of the composition and evolution history of the Moon. Except for the small amount of unbrecciated crystalline rocks, the majority of lunar meteorites are breccias which consist mainly of high land anorthositic breccias, mare basaltic breccias and the mingled breccias. According to petrographic analyses, especially clasts, lunar meteorites contain the variety of clasts as anorthosites, basalts, gabbros, troctolites, norites and KREEP rocks. There are more and more KREEP components found in lunar meteorites, in which the VHK KREEP clasts in SaU 169 may represent the urKREEP magma, and these KREEP components will provide the important information of the KREEP origin. Some works indicate that there are 6 launching pairs identified and 9 possible launching sites from the Moon. And the discovery of the lunar symplectites has the significance of the shock metamorphism on the lunar surface. Furthermore, the isotopic ages and the composition of noble gases not only provide the important information of the processions of crystallization of lunar rocks and the formation of lunar crust, but also get insight of the history of shock events on the lunar surface.