Extreme oxygen-isotope compositions in magnetite from unequilibrated ordinary chondrites

Article Abstract:

In situ oxygen-isotope measurements of magnetic grains in unequilibrated ordinary chondrites have been used to investigate the oxgyen isotopic composition of gas, which is the dominant oxygen reservoir. The results of this research imply that a nebular component of high-delta17O H2O was incorporated into the parent asteroid of the unequilibrated ordinary chondrites. It would be interesting to determine whether the nebular H2O(g) could have had such a high delta17O value while the silicate precursors of the chondrules were forming.

Oxygen, Oxygen isotopes, Magnetite

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Nature of the Earth's earliest crust from hafnium isotopes is single detrital zircons

Article Abstract:

Hafnium-isotope data is reported for 37 individual grains of terrestrial zircons from the Narryer Gneiss Complex, Australia, with U-Pb ages of up to 4.14 Gyr. The data was obtained using multiple-collector plasma-source mass spectrometry, and it was found that none of the grains has a depleted mantle signature, but several came from a source with a hafnium-isotope composition similar to chondritic meteorites. Over half of the grains appear to have formed by remelting.

Isotopes, Zircon, Hafnium

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Young chondrules in CB chondrites from a giant impact in the early solar system

Article Abstract:

Chondrules are believed to be the major constituent of chondritic meterioties that are formed during a brief, localized repetitive melting of dust in the proplanetary disk around the sun. These findings provide evidence of planet sized objects in the asteroid belt.

United States, Observations, Meteorites, Chondrules, Asteroid belts

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