不同类型陨石的宇宙射线暴露年龄及其宇宙化学意义

COSMIC-RAY EXPOSURE AGES OF THE DIFFERENT METEORITE TYPES AND THEIR COSMOCHEMICAL SIGNIFICANCE

本文主要依据现有的资料综述陨石分类 ,以及来自小行星带、月球和火星等不同类型陨石的宇宙射线暴露 (CRE)年龄及其宇宙化学意义。目前已确定有 1 3个球粒陨石群 ,至少 7个经受了高温和广泛熔融的无球粒陨石母体 ,以及 1 2个不同化学群的铁陨石母体。此外 ,还发现1 0个独特的球粒陨石、许多未分群的球粒陨石小群、铁陨石和铁陨石小群 ,它们也来自各自不同的母体。到目前为止 ,根据宇宙射线产生的核素 ,已测定了 1 60 0多个陨石的宇宙射线暴露年龄。由许多陨石类型的CRE年龄分布 ,我们可以识别出群集的宇宙射线暴露年龄 ,藉此可解释为母体上的碰撞 ,并释放大量的陨石碎块。小行星陨石、行星陨石及阿波罗月球样品的稀有气体同位素丰度和宇宙射线暴露年龄 ,已广泛应用于探索和了解不同类型陨石母体的宇宙射线暴露历史、冲击碰撞事件、暴露年龄与日心距离的关系、吸积形成母体前硅酸盐球粒的辐照历史、南极和沙漠陨石中成对陨石的判别、行星陨石 (火星及月球陨石 )

In this review on the bases of knowing data we summarized the classification of meteorite groups, cosmic-ray ages of the different meteorite types from asteroid belt,Moon and Mars. At present there are thirteen well-established chondrites,seven different parent bodies that experienced high temperatures and pervasive melting,and twelve main iron meteorite groups.These meteorite groups were derived from separate parent bodies. In addition to the established groups,there are about ten unique chondrites or chondrite grouplets, and also numerous ungrouped irons and iron grouplets.Up to date, based on cosmic-ray produced nuclides cosmic-ray exposure ages of more than 1600 meteorites have been determined. From the distribution of cosmic-ray exposure ages for many meteorite groups we recognize clusters that can be interpreted as the result of collisions on a parent body releasing large numbers of fragments. The isotopic abundances of rare gases and cosmic-ray exposure ages of asteroid meteorites, planetary meteorites and the Apollo lunar samples applied to clue up and understanding cosmic-ray exposure history of parent bodies of different meteorite types, collision events, the relationship between cosmic-ray exposure ages and heliocentric distance of the parent bodies, irradiation history of precompaction exposure of chondrules, pairing meteorites for the Antarctic meteorites and desert meteorites, the ejection history of planetary meteorites(martian and lunar meteorites), and relative ages of lunar craters and so on.