Abstract:

hock effects of 93 Grove Mountains(GRV) ordinary chondrites were studied in this paper,including fracture,various types of extinction,and recrystallization of silicates observed under optical microscopy.Shock-induced veins and pockets show various microtextures,decomposition and phase transformation of minerals.The confirmed high-pressure polymorphs of silicates are ringwoodite,majorite,pyroxene glass and maskelynite.Based on the shock effects and assemblages of high-pressure minerals,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) of 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 addition,there is relationship between petrologic types and shock stages,with most heavily shocked samples observed in equilibrated ordinary chondrites(especially Type 5 and 6).