We report the petrology and oxygen isotopic composition, using a Cameca NanoSIMS 50L ion microprobe, of a plagioclase–olivine inclusion, C#1, found in the Ningqiang carbonaceous chondrite. In addition to major phases (plagioclase, spinel and olivine), C#1 is also surrounded by a pyroxene rim (64 vol % Ca-rich and 36 vol % Ca-poor pyroxenes). On a three-isotope oxygen diagram, δ¹⁷O vs. δ¹⁸O, the compositions of individual minerals analyzed in C#1 fall along the carbonaceous chondrite anhydrous mineral line (CCAM), and oxygen isotopic compositions in C#1 show significant variability in δ¹⁸O and δ¹⁷O. The oxygen isotopic compositions of the pyroxene rim minerals are similar to those of the other host minerals, which suggests that the rim likely formed from the same melting process as the host. The rim is considered to have formed as a result of interaction between an ¹⁶O-poor gas and a melt. Some spinel grains are typically ¹⁶O-rich and likely of relict origin, which is similar to ¹⁶O-rich Ca-, Al-rich inclusions, which are probably a precursor of C#1. The inclusion then likely melted in an ¹⁶O-poor region where chondrules form, accompanied by oxygen isotope exchange with an ¹⁶O-poor gas. Some anorthite, pyroxene and spinel might have undergone fluid-assisted thermal metamorphism on the Ningqiang chondrite parent body. The oxygen isotope data and evolution of the C#1 plagioclase–olivine inclusion are similar with those of Al-chondrules in chondrites.

中文翻译：

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宁强斜长石-橄榄石包裹体中氧同位素组成与富铝球粒相似

我们使用 Cameca NanoSIMS 50L 离子微探针报告了在宁强碳质球粒陨石中发现的斜长石-橄榄石包裹体 C#1 的岩石学和氧同位素组成。除了主要相（斜长石、尖晶石和橄榄石）外，C#1 还被辉石边缘包围（64 vol% 富钙辉石和 36 vol% 缺钙辉石）。在三同位素氧图上，δ ¹⁷ O vs. δ ¹⁸ O，C#1 中分析的单个矿物的组成沿着碳质球粒陨石无水矿物线（CCAM），C#1 中的氧同位素组成显示出显着的变异性在δ ¹⁸ O 和δ ¹⁷O.辉石边缘矿物的氧同位素组成与其他寄主矿物的氧同位素组成相似，这表明该边缘很可能是由与寄主相同的熔融过程形成的。边缘被认为是由于贫¹⁶ O 气体和熔体之间相互作用而形成的。一些尖晶石晶粒通常富含¹⁶ O，可能是残渣来源，类似于富含¹⁶ O 的 Ca、Al 夹杂物，它们可能是 C#1 的前体。然后包裹体很可能在一个¹⁶ O 贫乏的区域熔化，在那里形成球粒，伴随着氧同位素与¹⁶O-贫气。一些钙长石、辉石和尖晶石可能在宁强球粒陨石母体上经历了流体辅助热变质作用。C#1斜长石-橄榄石包裹体的氧同位素数据和演化与球粒陨石中的Al-球粒相似。