The Provenances of Asteroids, and Their Contributions to the Volatile Inventories of the Terrestrial Planets

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Science  12 Jul 2012:
DOI: 10.1126/science.1223474

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Determining the source(s) of hydrogen, carbon, and nitrogen accreted by Earth is important for understanding the origins of water and life, and for constraining dynamical processes that operated during planet formation. Chondritic meteorites are asteroidal fragments that retain records of the first few million years of solar system history. The D/H values of water in carbonaceous chondrites and comets are distinct from one another, implying that they formed in a different region of the solar system, contrary to predictions of recent dynamical models. The D/H values of water in carbonaceous chondrites also argue against an influx of water ice from the outer solar system, which has been invoked to explain the non-solar oxygen isotopic composition of the inner solar system. The bulk hydrogen and nitrogen isotopic compositions of CI chondrites suggest that they were the principal source of the Earth's volatiles.

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