PMC

(a) Fe-Si-Mg plot showing compositions of scoriaceious particles (n = 107) in the present collection compared with the matrix compositions of different groups/sub-groups of chondritic meteorites. Data for different groups/sub-groups of chondritic meteorites are from: CM chondrite data^–; CV chondrite data^–; CO chondrite data^,,; CI chondrite data^,,–; CR chondrite data^,; EH chondrite data; LL chondrite data^,,; L chondrite data; H chondrite data^,; UOC chondrite data^,. (b) Triangular plot showing the compositions of glassy, hardened particles (n = 12) in comparison with the matrices of different groups/sub-groups of chondritic meteorites. Data for different groups/sub-groups of chondritic meteorites are from: CM chondrite data^–; CV chondrite data^–; CO chondrite data^,,; CI chondrite data^,,–; CR chondrite data^,; EH chondrite data; LL chondrite data^,,; L chondrite data; H chondrite data^,; UOC chondrite data^,.

Back-scattered electron (BSE) images of the 8 ZT CAIs studied here. ZT1 is a coarse-grained type B1 CAI from the CV3_red chondrite Leoville; it possesses a mantle of melilite (Mel) surrounding a core enriched in pyroxene (Px) and spinel (Sp). ZT2 is a coarse-grained type B1 CAI from the CV3_red chondrite Leoville; it possesses a mantle of melilite (Mel) surrounding a core enriched in pyroxene, spinel, and anorthite (An). ZT3 is a fine-grained spinel-pyroxene CAI from the CV3_ox chondrite NWA 6991; in addition to abundant spinel and pyroxene, ZT3 also contains some melilite and anorthite. ZT4 is a coarse-grained compact type A (CTA) CAI from the CV3_an chondrite NWA 7891; this CAI features a spinel-rich rim and an interior abundant in melilite that encloses some perovskite (Pv) grains. ZT5 is a coarse-grained CAI from the CV3_an chondrite NWA 7891; it contains spinel, pyroxene, melilite, and anorthite. ZT7 is a coarse-grained CTA CAI from the CV3_ox chondrite NWA 3118; this CAI features a spinel-rich rim and an interior abundant in melilite that encloses grains of pyroxene, perovskite, and spinel. ZT8 is a coarse-grained CAI from the CV3_ox chondrite NWA 3118 that most closely resemble a CTA CAI; it features abundant melilite enclosing grains of pyroxene and spinel. ZT9 is a fine-grained spinel-rich inclusion from the CV3_ox chondrite NWA 3118.

Texture of the brecciated LL3 chondrite NWA 4522, which consists of subrounded cluster chondrite clasts, embedded in a clastic matrix. This matrix consists mainly of small cluster chondrite clasts, intact chondrules, chondrule fragments, and very fine‐grained dust. Courtesy Carsten Giessler; width of image: ~4.5 cm.

Backscattered electron images of (a) the moderately altered CM chondrite Jbilet Winselwan showing rimmed chondrules in a tochilinite‐cronstedtite‐intergrowth‐rich matrix; (b) the relatively unaltered CM chondrite Maribo, also with abundant tochilinite (Tch) and cronstedtite (Crn); (c) CR chondrite NWA 6043 with abundant FeNi metal (met); (d‐e) CM chondrite Bells also contains abundant metal grains (for additional images, see also Van Kooten et al. ). Metal in altered CM chondrites is usually not present (Rubin et al. ) and the most unaltered CM chondrites Paris and Maribo have metal abundances of ~3 vol% (Hewins et al. ; Van Kooten et al. ). (Color figure can be viewed at http://www.wileyonlinelibrary.com.)