We studied a unique super-refractory inclusion with a core-mantle structure from CO3.0 Yamato 81020 by secondary ion mass spectrometry, electron microprobe, and scanning electron microscope techniques. The core consists largely of hibonite and nonstoichiometric Al-rich spinel indicating formation as a liquid at an exceptionally high temperature (>1900 °C). The mantle consists almost entirely of melilite with gehlenitic compositions (ranging from Åk₂ to Åk₂₅). The oxygen- and magnesium-isotopic compositions of the core and mantle are very different; typically, Δ¹⁷O (≡δ¹⁷O − 0.52 δ¹⁸O) ~–26‰ and ƒ_Mg (mass fractionation of Mg isotopes) ~10‰/amu in the core and Δ¹⁷O ~–7‰ and ƒ_Mg ~1‰/amu in most of the mantle. The chemical and O, Mg-isotopic data indicate that the core and mantle formed in separate events, and that the melilite now in the core was formed during the mantle-melting event, probably filling preexisting voids and surficial cavities. Analyses of core and mantle phases plot along a single ²⁶Al-²⁶Mg isochron with initial (²⁶Al/²⁷Al)₀ corresponding to 4.8 ± 1.0 (±2σ) × 10^–5, suggesting a similar formation age to normal CAIs in chondrites.

中文翻译：

---

含有来自 CO3.0 球粒陨石 Yamato 81020 的非化学计量尖晶石的超难熔夹杂物

我们通过二次离子质谱、电子探针和扫描电子显微镜技术研究了来自 CO3.0 Yamato 81020 的具有核幔结构的独特超难熔包裹体。核心主要由黑锰矿和非化学计量的富铝尖晶石组成，表明在异常高温（> 1900°C）下以液体形式形成。地幔几乎完全由具有长晶长石成分的方镁石组成（范围从 Åk ₂到 Åk ₂₅）。地核和地幔的氧同位素和镁同位素组成非常不同；通常，核心中的 Δ ¹⁷ O (≡δ ¹⁷ O - 0.52 δ ¹⁸ O) ~–26‰ 和 ƒ _Mg (Mg 同位素的质量分馏) ~10‰/amu 和 Δ ¹⁷O ~–7‰ 和 ƒ _Mg ~1‰/amu 在大部分地幔中。化学和 O、Mg 同位素数据表明，地核和地幔是在不同的事件中形成的，现在地核中的黄橄榄石是在地幔熔融事件中形成的，可能填充了预先存在的空隙和地表空洞。沿单个²⁶ Al- ²⁶ Mg 等时线分析地核和地幔相图，初始 ( ²⁶ Al/ ²⁷ Al) ₀对应于 4.8 ± 1.0 (±2σ) × 10 ^–5，表明与球粒陨石中的正常 CAI 的形成年龄相似.