关键词: 陨石;矿物-岩石学特征;分类;风化程度;冲击变质;南极

Abstract:

Petrography and mineral chemistry of 100 meteorites collected from the Grove Mountains,Antarctica,were studied and their chemical-petrographic types were assigned.The chemical-petrographic types of these meteorites are presented below.Six are unequilibrated ordinary chondrites,including three H3 and three L3;92 meteorites are equilibrated ordinary chondrites,including 24 H-group(13 H4,10 H5,1 H6),64 L-group(2 L4,44 L5,18 L6) and 4 LL-group(3 LL4,1 LL5);the other two belong to stone-iron meteorites.In 6 unequilibrated ordinary chondrites,chondrules are well-shaped,and olivine and low-Ca pyroxene are commonly zoned and have wide ranges of composition.The olivine and low-Ca pyroxene in the other 92 equilibrated ordinary chondrites have similar composition,respectively,and to some degree it reflected thermodynamics equilibration in olivine and lowCa pyroxene.All ordinary chondrites,consisting of predominant weathering degrees of W1 and W2(>90%),suggest a weak weathering among Antarctica meteorites.~40 % meteorites experienced severe shock metamorphism,as indicated by the presences of shock-induced melt veins and pockets.These heavily shocked meteorites provide us with natural samples for study of high-pressure polymorphs of minerals.