Guangmingshan Liaoning Province , China Fell 1996 December 30, ~08:00 Beijing time Ordinary chondrite (H5) A 2.91 kg stone was recovered by Bingde Wang after a loud whistling sound was heard. The meteorite left a small crater in the frozen ground. Classification and mineralogy (Y. Lin, GIG ): olivine, Fa19.5±0.5; pyroxene, Fs17.3±0.5Wo1.2±0.3; kamacite contains 0.49 ± 0.05 wt% Co; shock stage, S1. Specimens: main mass, Dalian ; type specimen, 19.6 g, GIG . Read more
Title: Cosmic-ray exposure and gas retention ages of the Guang-mingshan (H5) chondrite Authors: Wang, Daode; Lin, Yangting; Liu, Jinyuan
Isotopic compositions of noble gases from the Guangmingshan chondrite were analysed. Based on the analyses of cosmogenic nuclei, cosmic-ray exposure age of the meteorite is (65±10.0) Ma (3He), (80±12) Ma (21Ne) and (65±10.0) Ma (38Ar), with an average of 70 Ma. This is the highest exposure age of H-group ordinary chondrites. Gas retention ages of K-Ar and U, Th-4He are (4230±100) Ma and (3300±60) Ma, respectively. The smaller ages of 3He than 21Ne and 4He than 40Ar suggest that both 3He and 4He lost together. This is probably related to a solar heating effect of a meteorite with a small perihelion during the last exposure period.