南极陨石GRV052483中岩石矿物学特征:撞击熔融型普通球粒陨石  

PETROLOGY-MINERALOGY OF GRV 052483 FROM THE GROVE MOUNTAINS,ANTARCTICA:AN L-CHONDRITE IMPACT-MELT ROCK

作　　者：张广良[1] 李春来[1] 刘建忠[1] 邹永廖[1] 欧阳自远[1] 

机构地区：[1]中国科学院国家天文台,北京100012

出　　处：《极地研究》2008年第2期201-207,共7页Chinese Journal of Polar Research

基　　金：国家科技基础条件平台建设项目(2005DKA21406)资助

摘　　要：南极陨石GRV052483样品为中国第22次南极科学考察队在蓝冰上发现的一块普通球粒陨石。初步研究发现,该样品中球粒结构并不发育。薄片中可见大量自形-半自形橄榄石斑晶镶嵌在细粒基质矿物中,具有典型的斑状结构。这些橄榄石斑晶大多为残留相,斑晶橄榄石和基质中主要矿物橄榄石、低钙辉石成分均一,平均橄榄石Fa值为24.7 mol%,而低钙辉石平均Fs值为21.1 mol%,斑晶中偶有粗粒长石玻璃化,根据岩相学及矿物成分特征,可确定此陨石为L6。不透明矿物含量较少,包括金属(铁纹石和镍纹石)与陨硫铁,此外可见少量的铬铁矿和磷灰石。冲击熔融脉发育、斑晶中粗粒长石玻璃化、基质中橄榄石、辉石、长石重结晶等现象说明该样品经历了强烈冲击,其冲击程度可能达到S6以上。因此,GRV052483可能为撞击熔融型L6普通球粒陨石。An ordinary chondrite （Sample No. GRV052483 ） was recovered on blue ice during the 22nd Chinese Antarctic Research Exploration in Grove Mountains, Antarctica. In thin section, the sample shows a recrystallization texture and the texture is not particularly chondritic. Most euhedral to subhedral olivine crystals are set in a mesostasis of fine-grained olivine, pyroxene, and tiny spheres of Ni, Fe-rich metal and sulfides. Most olivine grains are essentially relicts. The major silicate phases are olivine, orthopyroxene, and plagioclase, with trace clinopyroxene. The mean Fa of olivine crystals and matrix are 24.7 mol%, and the mean Fs of low-Ca pyroxene is 21.1 tool% in GRV052483. These values are in the L chondrite range. Metal and sulfides are Fe - Ni metal （ kamacite, taenite） and troilite. Minor phases are chromite and ap- atite. Abundant dark portions, numerous cracks and microfaults, as well as impact-meh veins, are also present. As a result, GRV052483 is an L6-chondrite impact-melt rock（ i. e. , shocked L-6 chondrite）.

关 键 词：南极 格罗夫山 普通球粒陨石 岩石矿物学 撞击熔融 

分 类 号：P185.83[天文地球—天文学] P619.28