A coordinated mineralogical and oxygen isotopic study of four fine-grained calcium-, aluminum-rich inclusions (CAIs) from the ALHA77307 CO3.0 carbonaceous chondrite was conducted. Three of the inclusions studied, 05, 1-65, and 2-119, all have nodular structures that represent three major groups, melilite-rich, spinel-rich, and hibonite-rich, based on their primary core mineral assemblages. A condensation origin was inferred for these CAIs. However, the difference in their primary core mineralogy reflects unique nebular environments in which multiple gas-solid reactions occurred under disequilibrium conditions to form hibonite, spinel, and melilite with minor perovskite and Al,Ti-rich diopside. A common occurrence of a diopside rim on the CAIs records a widespread event that marks the end of their condensation as a result of isolation from a nebular gas. An exception is a rare inclusion 2-112 that contains euhedral spinel crystals embedded in melilite, suggesting this CAI had been re-melted. All of the fine-grained CAIs analyzed in ALHA77307 are uniformly 16O-rich with an average Δ17O value of ~-22 ± 5‰ (2σ), indicating no apparent correlation between their textures and oxygen isotopic compositions. We therefore conclude that a prevalent 16O-rich gas reservoir existed in a region of the solar nebula where CO3 fine-grained CAIs formed, initially by condensation and then later, some of them were reprocessed by melting event(s).

中文翻译：

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不同矿物学和质地的富含16O的细粒富含Ca-Al的夹杂物的起源。

对来自ALHA77307 CO3.0碳质球粒陨石的四种细粒富含钙，铝的夹杂物（CAI）进行了矿物学和氧同位素研究。所研究的三个夹杂物05、1-65和2-119均具有结核状结构，根据它们的主要核心矿物组合，它们代表了三个主要组，富含富铝红柱石，富含尖晶石和富含锂铁矿。对于这些CAI，推断出缩合来源。然而，它们的主要核心矿物学上的差异反映了独特的星云环境，在这种环境中，在不平衡条件下发生了多种气固反应，形成了钙钛矿，尖晶石和富铝绿柱石和富含Al，Ti的透辉石的辉石。CAI上透辉石边缘的普遍发生记录了一个广泛的事件，这标志着由于与星云气体隔离而导致其凝结的结束。一个例外是稀有夹杂物2-112，其内含嵌在陨石中的正方尖晶石晶体，表明此CAI已重新熔化。在ALHA77307中分析的所有细粒CAI均富含16O，平均Δ17O值为〜-22±5‰（2σ），表明其织构与氧同位素组成之间没有明显的相关性。因此，我们得出结论，在太阳星云的区域中存在一个普遍存在的富含16O的气藏，最初是通过凝结形成CO3细粒CAI，然后通过熔化事件对其中一些进行了重新处理。暗示此CAI已重新融合。在ALHA77307中分析的所有细粒CAI均富含16O，平均Δ17O值为〜-22±5‰（2σ），表明其织构与氧同位素组成之间没有明显的相关性。因此，我们得出结论，在太阳星云的区域中存在一个普遍存在的富含16O的气藏，最初是通过凝结形成CO3细粒CAI，然后通过熔化事件对其中一些进行了重新处理。表示此CAI已重新融合。在ALHA77307中分析的所有细粒CAI均富含16O，平均Δ17O值为〜-22±5‰（2σ），表明其织构与氧同位素组成之间没有明显的相关性。因此，我们得出结论，在太阳星云的区域中存在一个普遍存在的富含16O的气藏，最初是通过凝结形成CO3细粒CAI，然后通过熔化事件对其中一些进行了重新处理。