Oxygen isotope ratios and elemental compositions of porphyritic chondrules and olivine and pyroxene fragments in the Asuka-881020 CH chondrite were analyzed. The oxygen isotope ratios inside individual porphyritic chondrules are homogeneous within the uncertainty, except for relict grains of olivine and low-Ca pyroxene that have distinct oxygen isotope ratios. The average oxygen isotope ratios of the individual chondrules plot along and above the primitive chondrule mineral (PCM) line with ΔO (=δO – 0.52 × δO) values from −4.7 ‰ to +4.1 ‰. The olivine and pyroxene fragments, which have ΔO values ranging from −2.1 ‰ to +3.2 ‰, are likely to be fragments of the porphyritic chondrules.

中文翻译：

---

Asuka-881020 CH 球粒陨石 II 的氧同位素研究：斑状球粒

分析了 Asuka-881020 CH 球粒陨石中斑状球粒以及橄榄石和辉石碎片的氧同位素比率和元素组成。除了具有不同氧同位素比的橄榄石和低钙辉石残粒外，单个斑状球粒内部的氧同位素比在不确定性范围内是均匀的。各个球粒的平均氧同位素比沿着原始球粒矿物 (PCM) 线绘制，ΔO (=δO – 0.52 × δ18O) 值从 -4.7 ‰ 到 +4.1 ‰。橄榄石和辉石碎片的ΔO值范围为-2.1‰到+3.2‰，很可能是斑状球粒的碎片。