Clesi Vincent, Bouhifd Mohamed Ali, Bolfan-Casanova Nathalie, Manthilake Geeth, Schiavi Federica, Raepsaet Caroline, Bureau Hélène, Khodja Hicham, Andrault Denis
Laboratoire Magmas et Volcans, Université Clermont Auvergne, CNRS UMR 6524, Observatoire de Physique du Globe de Clermont Ferrand-Institut de Recherche pour le Développement, Campus Universitaire des Cézeaux, 6 Avenue Blaise Pascal, 63178 Aubière Cedex, France.
Laboratoire d'Etude des Eléments Légers, Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Énergie, Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif sur Yvette Cedex, France.
Sci Adv. 2018 Mar 14;4(3):e1701876. doi: 10.1126/sciadv.1701876. eCollection 2018 Mar.
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.
由于在地核-地幔分离过程中可能存在亲铁行为，氢被认为是地球核心中的一种重要轻元素。我们利用硅酸盐相中氢含量为450至1500 ppm、压力为5至20 GPa、氧逸度在IW - 3.7和IW - 0.2之间变化（比铁-方铁矿缓冲剂低0.2至3.7对数单位）以及典型的行星核心铁合金，再现了行星分异条件。我们报告的氢在金属-硅酸盐之间的分配系数约为2×10，比之前报道的低两个数量级，表明其具有亲石行为。我们的结果意味着地球和火星核心中的氢含量约为60 ppm。一个简单的水收支模型表明，行星形成物质最初所含的90%的水在行星吸积过程中流失了。留存下来的水优先分离到行星地幔中。
