28块南极陨石的类型研究

STUDIES ON THE TYPES OF 28 ANTARCTIC METEORITES

本文研究的28块陨石,均为我国第16次南极科学考察队,在南极格罗夫山地区回收。由于样品量有限,每个样品仅有一个光簿片。利用透反两用的偏光显微镜,进行陨石结构,矿物组成等一些现象观察。它们都是石质陨石,有球粒陨石和无球粒陨石。根据球粒发育程度,分为五种类型。用电子探针分析陨石中矿物的化学成份。有两块为无球粒陨石,GRV 99018为钙长辉长无球粒陨石,GRV 99027为橄辉无球粒陨石。利用Dodd(1981)和Wasson(1985)球粒陨石化学群分类原则,将26块普通球粒陨石进行化学群的分类,两者划分的结果基本吻合。前者H群有6块,L群有9块,LL群有8块,另3块陨石近于L群(GRV 99019,GRV 99021,GRV99026)。后者H群有5块,GRV 99010近于L群,它可为H/L,L群有9块,L/LL群有2个,LL群有6块,而GRV 99019,GRV 99021和GRV 99026三块陨石与三个群的数据相差较大,它们属于非平衡球粒陨石,可能是L。26块普通球粒陨石,有5个为非平衡普通球粒陨石,其它21个为平衡球粒陨石。21个平衡普通球粒陨石的岩石类型,主要为4—6。

The 28 Antarctic meteorites have been collected for the second time from the Grove Mountains of East Antarctica, during the 16th Chinese National Antarctic Research Expedition in 1999-2000 austral season. The 28 meteorites are all stones. According to the chondrule growing the meteorites can be divided into 5 types. GRV 99018 and GRV 99027 are achon-drites, other 26 meteorites are ordinary chondrites. These meteorites belong to different chemical groups ; H-group 5 , H/L-group 1, L-group have 9 , L/LL-group 2, LL-group 6, and L-group 3. Their petrologic types are: uneqquilibrated ordinary chondrites 5, the eqquilibrated ordinary chondrites 21. The majority are of types 4-6.