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Shape and porosity of refractory inclusions in CV3 chondrites: A micro‐computed tomography (µCT) study
Author(s) -
Zhang Mingming,
Clark Brett,
King Ashley J.,
Russell Sara S.,
Lin Yangting
Publication year - 2021
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.13635
Subject(s) - chondrite , kamacite , metasomatism , meteorite , refractory (planetary science) , parent body , geology , porosity , mineralogy , olivine , shock metamorphism , astrobiology , geochemistry , materials science , mantle (geology) , metallurgy , composite material , physics
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.