New constraints from ²⁶Al-²⁶Mg chronology of anorthite bearing chondrules in unequilibrated ordinary chondrites.

ABSTRACT: ²⁶Al-²⁶Mg ages were determined for 14 anorthite-bearing chondrules from five different unequilibrated ordinary chondrites (UOCs) with low petrologic subtypes (3.00-3.05). In addition, oxygen three isotopes of these chondrules were also measured. The selected chondrules are highly depleted in alkali elements, and anorthite is the only mesostasis phase, though they show a range of mafic mineral compositions (Mg# 76-97 mole%) that are representative of chondrules in UOCs. The mean ∆¹⁷O values in these chondrules range from -0.44 ± 0.23‰ to 0.49 ± 0.15‰, in good agreement with previous studies of plagioclase-bearing chondrules from UOCs. Anorthite in all chondrules exhibit resolvable excess ²⁶Mg (> 1.0 ± 0.4‰). Their inferred (²⁷Al/²⁶

SUBMITTER: Siron G 

PROVIDER: S-EPMC8740609 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature