2:30 PM - 2:45 PM
[SIT18-03] Melting curve of FeS at Martian core condition
Keywords:Mars, Core, melting curve, FeS
To constrain the thermal and internal structures of the Martian core, it is important to determine the melting temperature of Fe-S alloys at the Martian core conditions. Compared to Fe-rich side in the Fe-FeS system, melting curve of S-rich side is poorly constrained. Although the melting curve of end member FeS has been reported in several previous studies, these previous studies show a large difference (400 K difference at 20 GPa). In this study, we determined the melting curve of FeS at 12-37 GPa based on in situ X-ray diffraction (XRD) measurement using laser heated diamond anvil cell (DAC).
High pressure experiments were conducted using symmetric DAC with a culet size of 300 mm. FeS sample and RbBr pressure standard is enclosed next to each other in a hole of Re gasket. These were sandwiched between the Al2O3 disks. The experiments were carried out at BL10XU beamline, SPring-8 synchrotron facility. An monochromatized X-ray of 30 keV was used. The XRD measurements were conducted using a flat panel detector. High temperature was generated using a double-sided fiber laser heating. Melting of the sample was identified from disappearance of XRD peaks of the FeS sample in the 2D XRD image.
in situ XRD measurement was performed at 12.4–36.7 GPa and 1430–2820 K and melting of FeS V was determined in the pressure range of 13.9–34.7 GPa. The melting temperatures of FeS obtained in this study were fitted using the Simon and the Kraut-Kennedy equations to draw a melting curve of FeS. A difference between the melting curves from two equations is only 50 K at 40 GPa. The melting curve from this study is close to that from Williams and Jeanloz (1990), whereas the slope of the curve in this study is more gentle. By comparing the obtained melting curve with some thermal models of the Martian core, we will discuss molten state and possible internal structure of the Martian core.
High pressure experiments were conducted using symmetric DAC with a culet size of 300 mm. FeS sample and RbBr pressure standard is enclosed next to each other in a hole of Re gasket. These were sandwiched between the Al2O3 disks. The experiments were carried out at BL10XU beamline, SPring-8 synchrotron facility. An monochromatized X-ray of 30 keV was used. The XRD measurements were conducted using a flat panel detector. High temperature was generated using a double-sided fiber laser heating. Melting of the sample was identified from disappearance of XRD peaks of the FeS sample in the 2D XRD image.
in situ XRD measurement was performed at 12.4–36.7 GPa and 1430–2820 K and melting of FeS V was determined in the pressure range of 13.9–34.7 GPa. The melting temperatures of FeS obtained in this study were fitted using the Simon and the Kraut-Kennedy equations to draw a melting curve of FeS. A difference between the melting curves from two equations is only 50 K at 40 GPa. The melting curve from this study is close to that from Williams and Jeanloz (1990), whereas the slope of the curve in this study is more gentle. By comparing the obtained melting curve with some thermal models of the Martian core, we will discuss molten state and possible internal structure of the Martian core.