Abstract:

Shock effects of 93 Grove Mountains ( GRV ) ordinary chondrites were studied in this work, including fracture, various types of extinction, and recrystallization of silicates observed under optical microscopy. Shock-induced veins and pockets how various microtextures, decomposition and phase transformation of minerals. The on firmed high-pressure polymorphs of silicates are ringwoodite, majorite, pyroxene lass and maskelynite. Based on the shock effects and assemblages of h igh-pressure  inerals, shock stages of all of 93 GRV chondrites were classified. In comparison with literature, the Grove Mountains meteorites have a higher fraction ( 23 out of 93) if heavily shocked samples ( S4-S5). Most of the heavily shocked meteorites are L group ( 22 out of 23), except for one H chondrite. The distinct shock metamorphism between H and L groups may indicate different surface properties of their parent bodies. In add ition, there is rela tionship between petrologic types and shock stages, with most heavily shocked samples observed in equilibrated ordinary chondrites ( especially Type 5 and 6).

Key words: Antarctic, Grove Mountains, chondrites, shock metamorphism, high-pressurem ineral