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Oxygen isotopic zoning of reversely zoned melilite crystals in a fluffy type A Ca‐Al‐rich inclusions from the Vigarano meteorite
Author(s) -
KATAYAMA Juri,
ITOH Shoichi,
YURIMOTO Hisayoshi
Publication year - 2012
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.12034
Subject(s) - melilite , meteorite , geology , oxygen , mineralogy , astrobiology , chemistry , physics , paleontology , organic chemistry , spinel
– The oxygen isotopic microdistributions within melilite measured using in situ secondary ion mass spectrometry correspond to the chemical zoning profiles in single melilite crystals of a fluffy type A Ca‐Al‐rich inclusions (CAIs) of reduced CV3 Vigarano meteorite. The melilite crystals show chemical reverse zoning within an individual single crystal from the åkermanite‐rich core to the åkermanite‐poor rim. The composition changes continuously with the crystal growth. The zoning structures suggest that the melilite grew in a hot nebular gas by condensation with decreasing pressure. The oxygen isotopic composition of melilite also changes continuously from 16 O‐poor to 16 O‐rich with the crystal growth. These observations suggest that the melilite condensation proceeded with change consistent with an astrophysical setting around the inner edge of a protoplanetary disk where both 16 O‐rich solar coronal gas and 16 O‐poor dense protoplanetary disk gas could coexist. Fluffy type A CAIs could have been formed around the inner edge of the protoplanetary disk surrounding the early sun.