陨石冲击历史和冲击变质分类研究进展

本文评述了近年来陨石冲击变质效应和压力温度历史研究的新进展。根据对冲击变质主要压标熔长石性质的最新分析结果和陨石冲击脉体矿物组合研究的成果,指出现有陨石冲击变质分类的主要特点和某些不完善之处。本文提出,陨石按照冲击变质特征可以划分为以下两类:一是含高密度相类,如熔长石和各种高压矿物;二是合低密度相类,如长石击变玻璃、低压熔融玻璃和低压矿物组合。在含高密度相陨石中,可根据高压相的产出种类特点进一步划分冲击阶段;而在含低密度相陨石中,可根据矿物的冲击熔融程度划分冲击阶段。

DISTRIBUTION OF THE PROGRESS IN THE SHOCK HISTORY AND SHOCK CLASSIFICATION OF METERORITES

This paper reviews the new results on the studies of shock effects of meteorites, and the shock-related pressure and temperature history. According to the studies of maskelynite and the mineral assemblages in the shock veins, it seems that the nowadays shock classifications of meteorites should be further modified. We suggest that the shocked meteorites could be classified into two groups; the group-A contains high-density phases, such as maskelynite and other high-pressure minerals; the group-B contains low-density phases, for instance diaplectic feldspar glass, molten glass and the assemblages of low-pressure minerals. The group-A can be further divided into subgroups according to the types and occurrence of high-pressure minerals, whereas the group-B can be further divided into subgroups based on the degree of melting of minerals and meteorites.