我国某些球粒陨石及中铁陨石稀有气体的同位素丰度

本文测定了剑阁球粒陨石、岩庄球粒陨石、亳县球粒陨石及渭源中铁陨石和新近降落的东乌珠穆沁中铁陨石的稀有气体同位素丰度，根据He、Ne及Ar的测定结果计算宇宙射线暴露年龄，剑阁、岩庄及亳县球粒陨石的宇宙射线暴露年龄分别为5．8Ma、2．5Ma及38．0Ma，东乌珠穆沁及渭源中铁陨石分别为172Ma及17Ma．

ISOTOPIC ABUNDANCES OF NOBLE GASES IN SOME CHONDRITES AND MESOSIDERITES FELL IN CHINA

Noble gas isotopic abundance of Jiange, Yanzhuang, Bo Xian ordinary chondrites, Weiyuang and recently recovered Deng Ujimqin mesosiderites are measured by the standard procedure and mass spectrometer and results reported in this paper. Based on 3He, 21Ne and 38Ar, cosmic-ray exposure ages are calculated. Gas retention ages are determined based on radiogenic 4He and 40Ar for three chondrites. Cosmic-ray exposure ages of Jiange, Yanzhuang and Bo Xian are 5.8Ma, 2.5Ma and 38.0Ma, respectively. The average ages are 172Ma for Deng Ujimqin and 17Ma for Weiyuang mesosiderites. These ages represent the duration of exposure to cosmic-rays after break-up and ejection from their parent bodies.