Fig. 13

a, b Three-isotope oxygen diagrams and c, d ∆¹⁷O values of primary and secondary minerals in the Allende coarse-grained igneous CAIs TS-34 (B1), TS-31 (B2), AJEF (B1), TS-21 (B2), All-2 (FoB), 100 (C), and 160 (C). Data for primary minerals in TS-34 are from Kawasaki et al. (2018). Spinel and most analyses of Al,Ti-diopside have ¹⁶O-rich compositions; anorthite and melilite are ¹⁶O-depleted to various degrees. Al,Ti-diopside grains in TS-34 show a large range of ∆¹⁷O that correlates with their igneous zoning: very Ti-rich pyroxene cores are ¹⁶O-depleted relative to Ti-poor pyroxene edges. Secondary minerals have generally ¹⁶O-poor compositions. The observed range of ∆¹⁷O of secondary minerals in individual CAIs is similar to those of primary melilite and anorthite. e, f ∆¹⁷O values of primary minerals in coarse-grained igneous CAIs of different types (CTA, B, FoB, and Cracked Egg that is rich in krotite (krt, CaAl₂O₄) and grossite (grs, CaAl₄O₇)) from CV chondrites. FUN (fractionation and unidentified nuclear effects) CAIs show large mass-dependent fractionation effects in oxygen isotopes indicating crystallization during melt evaporation in vacuum (Mendybaev et al. 2017). Melilite and anorthite in CV CAIs of all types are ¹⁶O-depleted relative to hibonite, spinel, forsterite, and fassaite. The observed O-isotope heterogeneity may reflect mineralogically controlled exchange with an aqueous fluid (∆¹⁷O = −3±2‰) on the CV parent asteroid. Gas-melt isotopic exchange in gaseous reservoirs of variable oxygen isotopic composition cannot be excluded. Data from Bullock et al. (2012), Connolly et al. (2019c), Krot et al. (2014), and Williams et al. (2017). g Three-isotope oxygen diagram and h ∆¹⁷O of secondary minerals in CAIs, chondrules, and matrices of the oxidized Allende-like CV chondrites. Most secondary minerals were measured without matrix-matched standards; magnetite is the only exception. Data from Choi et al. (1997), Krot et al. (2000, 2010), and Cosarinsky et al. (2008)