Affiliation:
1. Muséum National d’Histoire Naturelle UMR CNRS 7590 Institut de Minéralogie de Physique des Matériaux et de Cosmochimie IMPMC Sorbonne Université Paris France
2. CNRS IRD ISTerre Université Gustave Eiffel Université Grenoble Alpes Université Savoie Mont Blanc Grenoble France
3. Royal Observatory of Belgium Brussels Belgium
4. Synchrotron SOLEIL L’Orme de Merisiers Gif‐sur‐Yvette France
5. Earth and Planets Laboratory Carnegie Institution for Science Washington DC USA
Abstract
AbstractThe local structure and density of ternary Fe‐C‐S liquid alloys have been studied using a combination of in situ X‐ray diffraction and absorption experiments between 1 and 5 GPa and 1600–1900 K. The addition of up to 12 at% of carbon (C) to Fe‐S liquid alloys does not significantly modify the structure, which is largely controlled by the perturbation to the Fe‐Fe network induced by S atoms. The liquid density determined from diffraction and/or absorption techniques allows us to build a non‐ideal ternary mixing model as a function of pressure, temperature, and composition in terms of the content of alloying light elements. The composition of the Moon's core is addressed based on this thermodynamic model. Under the assumption of a homogeneous liquid core proposed by two recent Moon models, the sulfur content would be 27–36 wt% or 12–23 wt%, respectively, while the carbon content is mainly limited by the Fe‐C‐S miscibility gap, with an upper bound of 4.3 wt%. On the other hand, if the core is partially molten, the core temperature is necessarily lower than 1850 K estimated in the text, and the composition of both the inner and outer core would be controlled by aspects of the Fe‐C‐S phase diagram not yet sufficiently constrained.
Funder
European Research Council
Publisher
American Geophysical Union (AGU)
Subject
Space and Planetary Science,Earth and Planetary Sciences (miscellaneous),Geochemistry and Petrology,Geophysics
Cited by
1 articles.
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