Exposure ages and radiogenic ages of ureilite(GRV 024516) and ordinary chondrite(GRV 024517) from Antarctica

The GRV 024516 and GRV 024517 meteorite samples collected from Grove Montains, Antactica are ureilite and H5 ordinary chondrite, respectively. Based on the study of mineralogy-petrology,the cosmic-ray exposure ages and gas retention ages of these two meteorites were determinated and calculated. Their cosmic-ray exposure ages are 33.3 Ma, 51.7 Ma, and gas retention ages are 1936.8 Ma and 3720 Ma, respectively. The ureilite contains diamond, graphite and amorphous C, which are mainly carrier of noble gases indicating obviously shock metamorphism effects, which induced 40Ar partial loss. The H5 chondrite indicates thermal metamorphism of parent body,its gas retention age fall the range between 3220 Ma and 4510 Ma of the least shocked H5 chondrites.