Low hydrogen contents in the cores of terrestrial planets

Hydrogen has been thought to be an important light element in Earth's core due to possible siderophile behavior during core-mantle segregation. We reproduced planetary differentiation conditions using hydrogen contents of 450 to 1500 parts per million (ppm) in the silicate phase, pressures of 5...

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Bibliographic Details
Published in:Science advances 2018-03, Vol.4 (3), p.e1701876-e1701876
Main Authors: Clesi, Vincent, Bouhifd, Mohamed Ali, Bolfan-Casanova, Nathalie, Manthilake, Geeth, Schiavi, Federica, Raepsaet, Caroline, Bureau, Hélène, Khodja, Hicham, Andrault, Denis
Format: Article
Language:English
Subjects:
Chemical Sciences
Earth Sciences
Geochemistry
Material chemistry
Physical Sciences
Planetary Science
SciAdv r-articles
Sciences of the Universe
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Summary:Hydrogen has been thought to be an important light element in Earth's core due to possible siderophile behavior during core-mantle segregation. We reproduced planetary differentiation conditions using hydrogen contents of 450 to 1500 parts per million (ppm) in the silicate phase, pressures of 5 to 20 GPa, oxygen fugacity varying within IW-3.7 and IW-0.2 (0.2 to 3.7 log units lower than iron-wüstite buffer), and Fe alloys typical of planetary cores. We report hydrogen metal-silicate partition coefficients of ~2 × 10 , up to two orders of magnitude lower than reported previously, and indicative of lithophile behavior. Our results imply H contents of ~60 ppm in the Earth and Martian cores. A simple water budget suggests that 90% of the water initially present in planetary building blocks was lost during planetary accretion. The retained water segregated preferentially into planetary mantles.
ISSN:2375-2548
2375-2548
DOI:10.1126/sciadv.1701876