Young chondrules in CB chondrites from a giant impact in the early Solar System
- 1 August 2005
- journal article
- Published by Springer Science and Business Media LLC in Nature
- Vol. 436 (7053), 989-992
- https://doi.org/10.1038/nature03830
Abstract
Chondrules, which are the major constituent of chondritic meteorites, are believed to have formed during brief, localized, repetitive melting of dust (probably caused by shock waves) in the protoplanetary disk around the early Sun. The ages of primitive chondrules in chondritic meteorites indicate that their formation started shortly after that of the calcium-aluminium-rich inclusions (4,567.2 +/- 0.7 Myr ago) and lasted for about 3 Myr, which is consistent with the dissipation timescale for protoplanetary disks around young solar-mass stars. Here we report the 207Pb-206Pb ages of chondrules in the metal-rich CB (Bencubbin-like) carbonaceous chondrites Gujba (4,562.7 +/- 0.5 Myr) and Hammadah al Hamra 237 (4,562.8 +/- 0.9 Myr), which formed during a single-stage, highly energetic event. Both the relatively young ages and the single-stage formation of the CB chondrules are inconsistent with formation during a nebular shock wave. We conclude that chondrules and metal grains in the CB chondrites formed from a vapour-melt plume produced by a giant impact between planetary embryos after dust in the protoplanetary disk had largely dissipated. These findings therefore provide evidence for planet-sized objects in the earliest asteroid belt, as required by current numerical simulations of planet formation in the inner Solar System.Keywords
This publication has 18 references indexed in Scilit:
- Mg isotope evidence for contemporaneous formation of chondrules and refractory inclusionsNature, 2004
- Formation of metal and silicate globules in Gujba: a new Bencubbin-like meteorite fallGeochimica et Cosmochimica Acta, 2003
- Lead Isotopic Ages of Chondrules and Calcium-Aluminum-Rich InclusionsScience, 2002
- A model of the thermal processing of particles in solar nebula shocks: Application to the cooling rates of chondrulesMeteoritics & Planetary Science, 2002
- A New Astrophysical Setting for Chondrule FormationScience, 2001
- Planets in the asteroid beltMeteoritics & Planetary Science, 2001
- Large-Scale Thermal Events in the Solar Nebula: Evidence from Fe,Ni Metal Grains in Primitive MeteoritesScience, 2000
- The Origin of Chondrules at Jovian ResonancesScience, 1998
- Clumpy Disk Accretion and Chondrule FormationIcarus, 1993
- On the formation of meteoritic chondrules by aerodynamic drag heating in the solar nebulaEarth and Planetary Science Letters, 1984