Early differentiation of magmatic iron meteorite parent bodies from Mn–Cr chronometry

作者：Aryavart Anand, Jonas Pape, Martin Wille, Klaus Mezger, Beda A. Hofmann · 发表于：Geochemical Perspectives Letters · 年份：2021 · DOI：10.7185/geochemlet.2136 · 被引用次数：22 · 研究领域：Astro and Planetary Science、Geological and Geochemical Analysis、Planetary Science and Exploration

Magmatic iron meteorite groups such as IIAB, IIIAB and IVA, represent the largest sampling of extraterrestrial core material from the earliest accreted distinct planetary bodies in the solar system.Chromium isotope compositions of chromite/daubréelite from seven samples, translated into 53 Cr/ 52 Cr model ages, provide robust time information on planetary core formation.These ages are within ∼1.5 Ma after formation of calcium-aluminium-rich inclusions (CAIs) and define the time of metal core formation in the respective parent bodies, assuming metal-silicate separation was an instantaneous event that induced strong chemical fractionation of Mn from the more siderophile Cr.The early core formation ages support accretion and differentiation of the magmatic iron meteorite parent bodies to have occurred prior to the chondrule formation interval.The calibration of Mn-Cr ages with established Hf-W ages of samples from the same magmatic iron meteorite groups constrains the initial ε 53 Cr of the solar system to -0.30 ± 0.05, and thus lower than previously estimated.