Chromium Isotopic Evidence for Mixing of NC and CC Reservoirs in Polymict Ureilites: Implications for Dynamical Models of the Early Solar System
Open Access
- 28 January 2021
- journal article
- research article
- Published by American Astronomical Society in The Planetary Science Journal
- Vol. 2 (1), 13
- https://doi.org/10.3847/psj/abd258
Abstract
Nucleosynthetic isotope anomalies show that the first few million years of solar system history were characterized by two distinct cosmochemical reservoirs, CC (carbonaceous chondrites and related differentiated meteorites) and NC (the terrestrial planets and all other groups of chondrites and differentiated meteorites), widely interpreted to correspond to the outer and inner solar system, respectively. At some point, however, bulk CC and NC materials became mixed, and several dynamical models offer explanations for how and when this occurred. We use xenoliths of CC materials in polymict ureilite (NC) breccias to test the applicability of such models. Polymict ureilites represent regolith on ureilitic asteroids but contain carbonaceous chondrite-like xenoliths. We present the first 54Cr isotope data for such clasts, which, combined with oxygen and hydrogen isotopes, show that they are unique CC materials that became mixed with NC materials in these breccias. It has been suggested that such xenoliths were implanted into ureilites by outer solar system bodies migrating into the inner solar system during the gaseous disk phase ∼3–5 Myr after CAI, as in the “Grand Tack” model. However, combined textural, petrologic, and spectroscopic observations suggest that they were added to ureilitic regolith at ∼50–60 Myr after CAI, along with ordinary, enstatite, and Rumuruti-type chondrites, as a result of the breakup of multiple parent bodies in the asteroid belt at this time. This is consistent with models for an early instability of the giant planets. The C-type asteroids from which the xenoliths were derived were already present in inner solar system orbits.Keywords
Funding Information
- National Aeronautics and Space Administration (NNX17AH09GS03)
- National Aeronautics and Space Administration (80NSSC19K0507)
- National Aeronautics and Space Administration (NNX16AD34G)
This publication has 117 references indexed in Scilit:
- 26Al‐26Mg isotope systematics of the first solids in the early solar systemMeteoritics & Planetary Science, 2013
- 40 Ar/ 39 Ar ages of impacts involving ordinary chondrite meteoritesGeological Society, London, Special Publications, 2013
- Radar-Enabled Recovery of the Sutter’s Mill Meteorite, a Carbonaceous Chondrite Regolith BrecciaScience, 2012
- Populating the asteroid belt from two parent source regions due to the migration of giant planets—“The Grand Tack”Meteoritics & Planetary Science, 2012
- The Provenances of Asteroids, and Their Contributions to the Volatile Inventories of the Terrestrial PlanetsScience, 2012
- Widespread54Cr Heterogeneity in the Inner Solar SystemThe Astrophysical Journal, 2007
- Thermodynamic constraints on fayalite formation on parent bodies of chondritesMeteoritics & Planetary Science, 2006
- The fall and recovery of the Tagish Lake meteoriteMeteoritics & Planetary Science, 2006
- The surface composition of Trojan asteroids: constraints set by scattering theoryIcarus, 2004
- The composition of the Trojan asteroidsNature, 1980