Refractory calcium‐aluminum‐rich inclusions (CAIs) and amoeboid olivine aggregates (AOAs) in chondritic meteorites are the earliest solids of our solar system, bearing the information of nebular condensation as well as accretion and asteroidal shock and metasomatism processes. While the compositions of refractory inclusions have been intensely studied for ~50 years, their physical properties such as shape and porosity are poorly constrained. Here, we present a microcomputed tomography (µCT) study on 16 refractory inclusions of condensate origin in five CV3 chondrites. We find that they are prolate or triaxial in shape with very rough morphologies. The CAIs have nodular textures and are thought to form by agglomerating individual nodules via collision‐induced bouncing and/or fragmentation, where the nodules were grown by gas–solid reactions during condensation. On the parent body, refractory inclusions from the CV_R meteorite Leoville experienced intense shocks that led to the flattening of their shapes and lowering of their porosities. High‐temperature metasomatism in CV_OxA meteorites and low‐temperature metasomatism in CV_OxB meteorites do not seem to have large effects on the porosities of their refractory inclusions, which have similar ranges and pore‐size distributions. Instead, we infer that their pores are mostly inherited from the gas–solid condensation and subsequent agglomeration processes. The porosities of CAIs are higher than those of AOAs, which is mainly due to the high‐temperature sintering process of AOAs.

中文翻译：

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CV3球粒陨石中难熔夹杂物的形状和孔隙度：显微计算机断层扫描（µCT）研究

钙质陨石中的难熔钙铝夹杂物（CAIs）和阿片类橄榄石聚集体（AOA）是我们太阳系中最早的固体，带有星云凝结，吸积和小行星冲击以及变质过程的信息。尽管对耐火夹杂物的成分进行了约50年的深入研究，但它们的物理性质（如形状和孔隙率）受到的约束却很有限。在这里，我们对5个CV3球粒陨石中的凝析油来源的16种难熔夹杂物进行了微计算机断层扫描（µCT）研究。我们发现它们呈长圆形或长圆形，具有非常粗糙的形态。CAI具有结节纹理，并被认为是通过碰撞诱发的跳动和/或破碎使单个结节聚结而形成的，在凝结过程中，结节是通过气固反应生长的。在母体上，简历中的难熔夹杂物_R陨石Leoville受到强烈冲击，导致其形状变平并降低了孔隙率。在CV高温交代_OXA陨石和低温交代在CV _OXB陨石似乎并没有对他们的耐火材料夹杂物的孔隙率，它们具有类似的范围和孔隙大小分布有很大的影响。取而代之的是，我们推断它们的孔主要是由气固凝结和随后的团聚过程所继承。CAIs的孔隙率高于AOAs，这主要是由于AOAs的高温烧结过程所致。