Re-Os Ages of Group IIA, IIIA, IVA, and IVB Iron Meteorites

1996/02/23 by M. I. Smoliar, R. J. Walker, John W. Morgan · 14 citations
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Astro and Planetary Science #Astrobiology #Chemistry #Chondrite #Geochemistry #Geological and Geochemical Analysis #Geology #Group (periodic table) #High-pressure geophysics and materials #Inorganic chemistry #Iron meteorite #Isochron #Isochron dating #Meteorite #Organic chemistry #Osmium #Physics #Rhenium

paper · doi:10.1126/science.271.5252.1099

openalex publication_date 1996/02/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/03

Abstract

Rhenium and osmium concentrations and osmium isotopic ratios of group IIA, IIIA, IVA, and IVB iron meteorites were determined by negative thermal ionization mass spectrometry with modified digestion and equilibration techniques. Precise isochrons are defined for all four groups. An absolute age of 4558 million years is assumed for group IIIA irons, leading to closure ages of 4537 ± 8, 4456 ± 25, and 4527 ± 29 million years for the group IIA, IVA, and IVB irons, respectively. The initial osmium-187/osmium-188 ratios of the IIA, IIIA, and IVA groups, as a function of crystallization age, suggest that the rhenium/osmium ratio of the parental materials to these asteroidal cores was similar to that of ordinary chondrites. Data for IVB irons, in contrast, indicate a different mode of formation and derivation from a distinctly nonchondritic osmium reservoir.

Citations

• Evidence for the existence of 107Pd in the early solar system
• The isotopic composition of Ag in meteorites and the presence of 107Pd in protoplanets

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