Space missions, along with ground-based observations, are providing unprecedented geophysical data regarding the interiors of the telluric planets in the solar system. Results from the Insight mission suggest that Mars has a large liquid core composed of an iron alloy rich in light elements. Chemical analysis of Martian meteorites and planetary differentiation models indicate that sulfur and oxygen are the most abundant light elements in the core. Yet, the phase diagram and the thermo-elastic properties of liquid alloys in the ternary Fe-S-O system under the pressure and temperature conditions of the Martian core remain largely unconstrained.
We performed X-ray diffraction measurements at the PSICHÉ beamline of the SOLEIL synchrotron on FeS, FeO and alloys in the Fe-FeO binary system within laser-heated diamond-anvil cells, collecting data in the 10-80 GPa range up to 4000 K. The ability to control the shape of the heating laser combined with temperature mapping enabled by the 4-color pyrometry system, ensured homogenous heating and precise temperature determination. Melting was constrained by tracking the appearance and evolution of the diffuse scattering signal typical of liquids, along with parallel assessment of discontinuities in the optical properties of the investigated samples.
In this presentation, we will outline the developed experimental protocol and present the melting curves obtained for FeS, FeO and the Fe-FeO binary eutectic. Our results will be compared with earlier determinations, addressing ongoing controversies and providing a foundation for an improved understanding of the melting relations in the Fe-S-O ternary system under the conditions of Mars' core.
| Subject : | : | Oral |
| Topics | : | Solar System and Exoplanets |
| Topics | : | Planetary Volatiles |
| Keywords | : | Mars core ; iron alloys ; phase diagram ; high pressure ; high temperature ; diamond anvil cell |
| PDF version | : |  PDF version |
