Liquidus determination of the Fe-S and (Fe, Ni)-S systems at 14 and 24 GPa: Implications for the Mercurian core

1,2Allison Pease,2Jie Li
Earth and Planetary Science Letters 599, 117865 Link to Article []
1Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, 48824, USA
2Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, 48109, USA
Copyright Elsevier

Mercury has fascinated researchers for decades due to its sizable metallic core and weak magnetic field. The behavior of Fe-S and (Fe, Ni)-S systems provides constraints on core conditions and regimes of solidification to predict magnetic field strength. In this study, we investigate the melting behavior of the (Fe, Ni)-S system, a candidate composition to model the Mercurian core. We observe that the Fe-S liquidus has an inflection point at ∼10 wt.% S at 14 GPa and ∼11.5 wt.% S at 24 GPa, while (Fe, Ni)-S does not. At 24 GPa, Ni may lower the melting point of the Fe-S system by as much as 300 °C, indicating that solidification models and adiabatic calculations must account for the presence of Ni.


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