Although ordinary chondrite (OC) meteorites dominate observed falls, the identification of near-Earth and main-belt asteroid sources has remained elusive. Telescopic measurements of 35 near-Earth asteroids ( approximately3 kilometers in diameter) revealed six that have visible wavelength spectra similar to laboratory spectra of OC meteorites. Near-Earth asteroids were found to have spectral pro...

Recent observations of rapid cooling rates at high temperatures in several ordinary chondrite and primitive achondrite meteorite groups suggest the fragmentation their parent bodies near peak temperatures. We use analytic models for conductive collisional fragments to show that actively part a fragment experiences similar over large range This characteristic rate decays inversely with time larg...

Introduction: Light stable isotopes provide insights and constraints on nebular and parent body processes. Lithium isotope studies of chondrites offer such potential, with some specifically unique aspects. Lithium is monovalent, the lightest of nongaseous elements, it has a 15% mass difference between its 2 isotopes (Li and Li), it is fluid mobile, and it is one of the fastest diffusing element...

To examine the iron (Fe) isotopic heterogeneities of CI and ordinary chondrites, we have analyzed several large chips (approximately 1 g) from three CI chondrites and three ordinary chondrites (LL5, L5, and H5). The Fe isotope compositions of five different samples of Orgueil, one from Ivuna and one from Alais (CI chondrites), are highly homogeneous. This new dataset provides a dFe average of 0...

We review the chronology for the accretion and earliest evolution of asteroids and terrestrial planets as obtained by applying Hf-W chronometry to meteoritic and planetary samples. Internal Hf-W isochrons for CAIs and angrites yield an absolute age for CAIs of 4568.6±0.7 Ma, which is ~1.5 Ma older than previously determined from PbPb ages for CAIs. Hafnium-tungsten isochrons for H chondrites co...

The 53Mn-53Cr isotope systematics in ordinary chondrites constrains the accretion and thermal history of their parent bodies. Mineralogical observations olivine-spinel geothermometry suggest that chromite formed during prograde metamorphism with amount increasing petrologic grades type 3 to 6 chondrites. Assuming a chondritic evolution respective bodies, 53Cr/52Cr model ages for range from 3.99...