HR: 1340h
AN: MR43A-0870    [Abstracts]
TI: Equation of state of iron sulfide at the conditions of Galilean satellite cores
AU: * Vermylen, J P
EM: jvermyle@princeton.edu
AF: Princeton University, Department of Geosciences, Princeton, NJ 08544 United States
AU: Hongsresawat, S
AF: University of Chicago, Department of Geophysical Sciences, Chicago, IL 60637
AU: Speziale, S
AF: University of California, Department of Earth and Planetary Sciences, Berkeley, CA 94720 United States
AU: Shieh, S
AF: National Cheng Kung University, Department of Earth Sciences, Tainan, 701 Taiwan
AU: Kiefer, B
AF: New Mexico State University, Department of Physics, Las Cruces, NM 88003 United States
AU: Wang, Y
AF: University of Chicago, GSECARS, Argonne, IL 60439 United States
AU: Uchida, T
AF: University of Chicago, GSECARS, Argonne, IL 60439 United States
AU: Duffy, T S
EM: duffy@princeton.edu
AF: Princeton University, Department of Geosciences, Princeton, NJ 08544 United States
AB: The Galileo mission has revealed that Jupiter's satellites Io, Europa, and Ganymede are differentiated and likely have dense, metallic cores. Current structural models of the Galilean moons have assumed that core compositions will be in the Fe-FeS system because of the cosmochemical abundance of sulfur and its low eutectic temperatures. However, these models have generally assumed densities for FeS that are not based on measurements directly under the pressure-temperature range expected for the cores of the Galilean moons. The probable temperatures and pressures of the cores of the Galilean moons make FeS in the NiAs structure (FeS V) the most likely phase at core conditions. We have obtained energy-dispersive x-ray diffraction data of FeS from 0-15 GPa and 300-1100 K using the 250-ton multi-anvil press at the GSECARS sector of the Advanced Photon Source. From this dataset, a thermal equation of state of FeS V using the third-order Birch-Murnaghan equation will be constructed. Preliminary low-pressure density results for FeS V are in the range of 4.7 to 4.9 g/cm$^{3}$ from 1 to 2 GPa and from 600 to 900 K. Using a linear mixing model for Fe-FeS, these results indicate that the eutectic density at core conditions of the Galilean moons is approximately 13% larger than values typically used in existing models. We will construct a range of new interior models that satisfy the new equation of state for FeS as well as additional considerations from thermodynamics, rheology, compositional inferences, and accretion models.
DE: 3900 MINERAL PHYSICS
DE: 3919 Equations of state
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
SC: Mineral and Rock Physics [MR]
MN: 2004 AGU Fall Meeting