Abstract
A long-standing question in the planetary sciences asks what the Earth is made of. For historical reasons, volatile-depleted primitive materials similar to current chondritic meteorites were long considered to provide the ‘building blocks’ of the terrestrial planets. But material from the Earth, Mars, comets and various meteorites have Mg/Si and Al/Si ratios, oxygen-isotope ratios, osmium-isotope ratios and D/H, Ar/H2O and Kr/Xe ratios such that no primitive material similar to the Earth's mantle is currently represented in our meteorite collections. The ‘building blocks’ of the Earth must instead be composed of unsampled ‘Earth chondrite’ or ‘Earth achondrite’.
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Acknowledgements
Supported by NASA and NSF. We thank D. Lauretta for comments. A review by T. Owen brought noble gas ratios in Solar System bodies to our attention. Discussions with H. McSween, D. Kring, R. Boehler, D. Mao, L. Stixrude, A. Morbidelli, J. Lunine, F. Robert and T. Swindle have been helpful.
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Drake, M., Righter, K. Determining the composition of the Earth. Nature 416, 39–44 (2002). https://doi.org/10.1038/416039a
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DOI: https://doi.org/10.1038/416039a
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