Immiscible two-liquid regions in the Fe–O–S system at high pressure: Implications for planetary cores

Tsuno, K.; Ohtani, Eiji; Terasaki, Hidenori

doi:10.1016/j.pepi.2006.09.004

Cited by 42 publications

(87 citation statements)

References 41 publications

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“…Therefore, a homogenous Fe-O-S melt with a significant amount of oxygen can be formed in a terrestrial magma ocean exceeding 21 GPa, and significant amount of oxygen may be supplied to the Earth's outer core. McDonough and Sun [1995] proposed a geochemical model with a large amount of oxygen (5.8 wt.% O) and sulfur (1.9 wt.% S) in the outer core, and both the present experimental results and those by Tsuno et al [2007] support this model.…”

Section: Resultssupporting

confidence: 79%

“…[13] Closure of a liquid immiscibility gap at 21 GPa and 2573 K shown in Figure 4 [Tsuno et al, 2007] is supported by the recovered products showing the homogeneous textures. Therefore, a homogenous Fe-O-S melt with a significant amount of oxygen can be formed in a terrestrial magma ocean exceeding 21 GPa, and significant amount of oxygen may be supplied to the Earth's outer core.…”

Section: Resultsmentioning

confidence: 87%

“…However, these immiscibility gaps may be overestimated, since the two phases observed by Urakawa et al [1987] and Tsuno et al [2007] could be recovered products separated from the homogenous melt during quenching. On the other hand, homogeneous dendritic textures composed of FeS and FeO dendrites (Figure 3c), and Fe and FeO dendrites [Urakawa et al, 1987;Tsuno et al, 2007] show complete miscibility of the FeS-FeO and Fe-FeO melts at high temperature.…”

Section: Resultsmentioning

confidence: 99%

“…In order to assess the compositional models of the Earth's core [e.g., McDonough and Sun, 1995], liquid immiscibility in the Fe-O [Kato and Ringwood, 1989;Ringwood and Hibberson, 1990], Fe-O-S [Urakawa et al, 1987;Tsuno et al, 2007], and Fe-S-Si system [Sanloup and Fei, 2004] were investigated at high pressure. These results indicate that immiscible two-liquid regions exist in these systems, with important implications for the chemical compositions and formation processes of the cores of the Earth and Mars.…”

Section: Introductionmentioning

confidence: 99%

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In situ observation and determination of liquid immiscibility in the Fe‐O‐S melt at 3 GPa using a synchrotron X‐ray radiographic technique

Tsuno¹,

Terasaki²,

Ohtani³

et al. 2007

Geophysical Research Letters

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We have performed in situ experiments on liquid immiscibility in Fe‐O‐S melts at 3 GPa and up to 2203 K using a synchrotron X‐ray radiographic technique. The difference between immiscible melts and a miscible melt can be clearly observed in radiographs. The immiscibility gap of the Fe‐O‐S melt shrinks with increasing temperature at 3 GPa. Two separated phases appeared from a miscible melt during quenching. Without in situ observations, the two phases observed in quench textures would be interpreted as either quench products from primary immiscible melts at high temperature, or those exsolved from a homogeneous melt to immiscible melts passing through the stability field of immiscible melts during quenching. In situ measurements are required in order to determine the immiscibility gap of the liquid Fe with light element(s). Our results have important implications for the formation and chemical composition of the cores of Earth and Mars.

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Section: Resultssupporting

confidence: 79%

Section: Resultsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In situ observation and determination of liquid immiscibility in the Fe‐O‐S melt at 3 GPa using a synchrotron X‐ray radiographic technique

Tsuno¹,

Terasaki²,

Ohtani³

et al. 2007

Geophysical Research Letters

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“…Besides iron, the core of Mercury might also contain nickel up to 8wt%, which is the cosmic abundance of nickel. small and below about 1wt% for pressures below 10GPa (Tsuno et al, 2007).…”

Section: Corementioning

confidence: 92%

The interior structure of Mercury and its core sulfur content

Rivoldini

Hoolst

Verhoeven

2009

Icarus

102

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Depth-dependent interior structure models of Mercury are calculated for several plausible chemical compositions of the core and of the mantle. For those models, we compute the associated libration amplitude, obliquity, tidal deformation, and tidal changes in the external potential.In particular we study the relation between the interior structure parameters for five different mantle mineralogies and two different temperature profiles together with two extreme crust density values. We investigate the influence of the core light element concentration, temperature, and melting law on core state and inner and outer core size. We show that a sulfur concentration above 10wt% is unlikely if the temperature at the core mantle boundary is above 1850K and the silicate shell at least 240km thick. The interior models can only have an inner core if the sulfur weight fraction is below 5wt% for core mantle boundary temperature in the 1850K − 2200K range.Within our modeling hypotheses, we show that with the expected precision on the moment of inertia the core size can be estimated to a precision of about 50km and the core sulfur concentration with an error of about 2wt%. This uncertainty can only be reduced when more information on the mantle mineralogy of Mercury becomes available. However, we show that the uncertainty on the core size estimation can be greatly reduced, to about 25km, if tidal surface displacements and tidal variations in the external potential are considered.

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Thermodynamics of melting relations in the system Fe‐FeO at high pressure: Implications for oxygen in the Earth's core

Komabayashi

2014

JGR Solid Earth

219

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The thermodynamics of melting relations in the system Fe-FeO was investigated to the outer core-inner core boundary condition from a self-consistent thermodynamic database which was evaluated from the latest static high-pressure (P) and high-temperature (T) experiments. The evaluated database together with an existing nonideal mixing model for liquids reproduces experimental data on the eutectic composition and temperature to P = 50 GPa. On the other hand at the outer core pressures (136 to 330 GPa), employing an ideal solution model gives calculated eutectic temperatures of T = 2990-4330 K, which are also consistent with experimental data. Hence, the ideal solution model is applied to calculate the liquid property under outer core conditions and yields the eutectic compositions of Fe-7.2-9.1 wt % O. From the Gibbs free energy for the Fe-FeO liquids, I calculated the density, sound velocity, and isentropic temperature gradient of a hypothetical oxygen-bearing outer core. Under the outer core conditions, the addition of oxygen reduces the compressional wave velocity of iron liquid, moving it away from seismologically constrained values. An overall O-rich bulk outer core model is thus excluded. Seismological observations however suggest the presence of a low-velocity layer with a thickness of 60-70 km at the top of the outer core. The origin of such a low-velocity layer can be explained by an enrichment of oxygen which might be a consequence of chemical interactions between the core and mantle.

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Immiscible two-liquid regions in the Fe–O–S system at high pressure: Implications for planetary cores

Cited by 42 publications

References 41 publications

In situ observation and determination of liquid immiscibility in the Fe‐O‐S melt at 3 GPa using a synchrotron X‐ray radiographic technique

In situ observation and determination of liquid immiscibility in the Fe‐O‐S melt at 3 GPa using a synchrotron X‐ray radiographic technique

The interior structure of Mercury and its core sulfur content

Thermodynamics of melting relations in the system Fe‐FeO at high pressure: Implications for oxygen in the Earth's core

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