Abstract : 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$^{−1}$ , 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.
https://hal-cea.archives-ouvertes.fr/cea-01736955
Contributor : Serge Palacin
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Submitted on : Monday, March 19, 2018 - 8:17:15 AM
Last modification on : Monday, May 27, 2019 - 11:12:11 AM
Long-term archiving on : Tuesday, September 11, 2018 - 8:55:05 AM
