研究者詳細 - 寺﨑　英紀

Viscosity of silicate melts in CaMgSi(2)O(6)-NaAlSi(2)O(6) system at high pressure 査読

A Suzuki, E Ohtani, H Terasaki, K Funakoshi

PHYSICS AND CHEMISTRY OF MINERALS 32 ( 2 ) 140 - 145 2005年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

In situ X-ray viscometry of the silicate melts was carried out at high pressure and at high temperature. The viscosity of the silicate melts in the diopside(Di)-jadeite(Jd) system was determined in the pressure range from 1.88 GPa to 7.9 GPa and in the temperature range from 2,003 K to 2,173 K. The viscosity of the Di 25%-Jd 75% melt decreases continuously to 5.0 GPa, whereas the viscosity of the Di 50%-Jd 50% melt increases over 3.5 GPa. The viscosity of the Di50%-Jd 50% melt reaches a minimum around 3.5 GPa. Since the amounts of silicon in the two melts are the same, the difference in the pressure dependence of the viscosity may be controlled by another network-forming element, i.e., aluminum. The difference in the pressure dependence of the viscosities in the melts with two intermediate compositions in the Di-Jd system is estimated to be due to the difference in the melt structures at high pressures and high temperatures.

DOI： 10.1007/s00269-005-0452-0

The effect of oxygen and sulphur on the dihedral angle between Fe-O-S melt and silicate minerals at high pressure: Implications for Martian core formation 査読

H Terasaki, DJ Frost, DC Rubie, F Langenhorst

EARTH AND PLANETARY SCIENCE LETTERS 232 ( 3-4 ) 379 - 392 2005年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

A crucial factor in the investigation of terrestrial planet core formation is whether or not a liquid iron-alloy can segregate from a solid silicate matrix. The interconnectivity of a core-forming liquid depends on the dihedral angle between liquid iron alloy and crystalline silicates at low melt fractions. Recent experimental studies at ambient pressure have implied that liquid iron-alloy can wet an olivine matrix under conditions of high oxygen and sulphur fugacities. We have examined the effects of varying sulphur and oxygen contents on the dihedral angle between liquid iron-alloy and crystalline silicates up to 20 GPa. The compositions studied are applicable to core formation on both the Earth and Mars and the pressure range investigated is applicable to over 80% of the depth of the entire Martian mantle. Dihedral angles in texturally equilibrated samples decrease with increasing sulphur content and also decrease significantly with increasing FeO content of silicates. Increasing the FeO content of silicates results in an increase in both the oxygen fugacity and oxygen solubility in the Fe-S, melt. Oxygen is found to have a larger effect in reducing the dihedral angle than sulphur. The dihedral angle between metallic melt and silicate crystals in the Martian mantle would have been closer to the wetting boundary of 60 degrees than in the Earth's interior, but it would be still too large (0 > 60 degrees) to allow percolation to occur to completion. These results show that melting of the silicate mantle is required to obtain complete metal-silicate separation, which therefore supports a magma ocean scenario for core formation on both Mars and Earth. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.epsl.2005.01.030

Ｘ線影像法を用いた金属融体の密度測定査読

鈴木昭夫, 大谷栄治, 寺崎英紀

日本岩石鉱物鉱床学会学術講演会講演要旨集 2005 ( 0 ) 92 - 92 2005年

Phase relations in peridotite-CO₂ system to 20 GPa 査読

Ghosh Sujoy, Ohtani Eiji, Litasov Konstantin, Suzuki Akio, Terasaki Hidenori

日本鉱物学会年会講演要旨集 2005 ( 0 ) 13 - 13 2005年

記述言語：英語出版者・発行元：日本鉱物科学会

Carbon dioxide and water are the most important volatile constituents in the Earth and they produce drastic changes in the melting phase relations and partial melt composition of the mantle peridotites. Study of the peridotite-CO₂ system is closely related to petrogenesis of kimberlite and diamond. There are a few high pressure mineral inclusions (i.e. majorite garnet and Ca & Mg perovskite) in diamond which suggest that kimberlites may be originated from the transition zone and lower mantle. Several experimental petrologists have studied the kimberlite and basalt-CO₂ systems, however the phase relations and melt compositions in the CO₂-bearing peridotite at high pressures are poorly constrained. Simplified peridotite-CO₂ system (like CMS or CMAS) has been studied at pressures up to 12 GPa (Canil and Scarfe, 1990), whereas complex peridotite-CO₂ systems have investigated only at lower pressures (up to 4 GPa, e.g. Wendlandt and Mysen, 1980). In this work we report the results on the phase relations and melt compositions of a model peridotite-CO₂ system determined at 10-20 GPa and temperature range from 1200 to 2100^oC.Our results show that solidus of carbonated peridotite is consistent with low-pressure data for CMAS-CO₂ system. Liquidus phase at 10-20 GPa is majorite garnet. At 10-15 GPa, crystallization sequence with decreasing temperature is garnet, olivine and clinoenstatite. Magnesite is the most important CO₂-rich phase stable in peridotite and clinoenstatite is an important phase in carbonated peridotite at 10-15 GPa.The partial melts formed by 10-25% melting at 10-20 GPa has high MgO (26-34 wt.%) and FeO (7.0-10.4 wt.%) and low SiO₂ (18-36 wt.%) and Al₂O₃ (0.5-1.3 wt.%) contents. It contains also 6-12 wt.% CaO, 0.6-2.0 wt.% Na₂O and 0.1-0.3 wt.% K₂O. The CO₂ contents in the melts are 14-32 wt.%. SiO₂-poor composition of partial melts is different to the results for melting of anhydrous or water-bearing peridotite. Partial melting of hydrous peridotite produce SiO₂-rich melts, which can be related to komatiite magmas (e.g. Litasov and Ohtani, 2002). The composition of low degree partial melts (10%) in present experiments is close to magnesiocarbonatites, whereas higher degree melting (20-25%) produce melts, which is close to kimberlite magmas.

DOI： 10.14824/kobutsu.2005.0.13.0

Immiscible two-liquid regions in the Fe-FeO-FeS system at high prebure

Kyusei Tsuno, Eiji Ohtani, Hidenori Terasaki

Joint 20th AIRAPT and 43rd EHPRG International Conference on High Pressure Science and Technology 2005年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Karlsruhe Forschungszentrum Karlsruhe gmbH

Summary: Melting relation in the Fe-FeO-FeS system, especially the immiscible two-liquid region has been investigated by using Kawai-Type multi-Anvil apparatus at 15 GPa, 1800-2200°C. The products recovered from 15 GPa and 2200°C show textures that are totally molten. The immiscible two liquids are observed in the starting compositions with 0-2.6 wt.% sulfur, whereas the miscible liquid is obtained in the composition of 7.5 wt.% sulfur. Sulfur is likely to narrow the immiscible two-liquid region in the Fe-FeO-FeS system at high prebure.

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Phase relationships and equations of state for FeS at high pressures and temperatures and implications for the internal structure of Mars 査読

S Urakawa, K Someya, H Terasaki, T Katsura, S Yokoshi, KI Funakoshi, W Utsumi, Y Katayama, YI Sueda, T Irifune

PHYSICS OF THE EARTH AND PLANETARY INTERIORS 143 469 - 479 2004年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

In situ X-ray diffraction experiments on Fes up to 22 GPa and 1600 K were carried out using large volume multianvil apparatus, combined with synchrotron radiation at SPring-8. We investigated phase stability relationships of Fes and determined the straight phase boundaries between Fes III (monoclinic phase) and Fes IV (hexagonal phase) to be T (K) = 20P (GPa) + 170 and between Fes IV and Fes V (NiAs-type phase) to be T (K) = 39.6 P (GPa) + 450. We also found anomalous behavior in the c/a ratio, thermal expansion, and isothermal compression of FeS V as well as FeS IV, in the pressure range 4-12 GPa. These anomalies in Fes can be attributed to the spin-pairing transition of Fe, and divides FeS IV and FeS V into the high-spin low-pressure phase (LPP) and the possibly low-spin high-pressure phase (HPP). In order to investigate the internal structure of Mars, we evaluated the equations of state for Fes IV (HPP) and Fes V (HPP). A least square fit to the experimental data yielded K(0T) = 62.5 +/- 0.9 GPa at T = 600 K and (dK(0)/dT) p = -0.0208 +/- 0.0028 GPa/K for Fes IV (HPP), and K(0T) = 54.3 +/- 1.0 GPa at T = 1000 K and (dK(0)/dT) = -0.0117 +/- 0.0015 GPa/K for Fes V (HPP) with fixed K' = 4. Thermal expansion coefficients were alpha = 7.16 x 10(-5) + 6.08 x 10(-8) T for FeS IV (HPP) and alpha = 10.42 x 10(-5) for Fes V (HIPP), respectively. Using these equations of state, we examined the internal structure of Mars that has a model mantle composition [Meteoritics 20 (1985) 367] and Fe-FeS core. Our models show that an Mg-silicate perovskite-rich lower mantle is stable only with the Fe-rich core having less than 20 wt.% sulfur. The polar moment of inertia factor C derived from Mars Pathfinder data [Science 278 (1997) 1749] is consistent with any compositions between Fe and Fes for the Martian core, but it excludes the presence of a crust thicker than 100 km. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.pepi.2003.12.015

Viscosity of liquid sulfur under high pressure 査読

H Terasaki, T Kato, K Funakoshi, A Suzuki, S Urakawa

JOURNAL OF PHYSICS-CONDENSED MATTER 16 ( 10 ) 1707 - 1714 2004年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IOP PUBLISHING LTD

The viscosity of liquid sulfur up to 9.7 GPa and 1067 K was measured using the in situ x-ray radiography falling sphere method. The viscosity coefficients were found to range from 0.11 to 0.69 Pa s, and decreased continuously with increasing pressure under approximately constant homologous temperature conditions. The observed viscosity variation suggests that a gradual structural change occurs in liquid sulfur with pressure up to 10 GPa. The L-L' transition in liquid sulfur proposed by Brazhkin et al (1991 Phys. Lett. A 154 413) from thermobaric measurements has not been confirmed by the present viscometry.

DOI： 10.1088/0953-8984/16/10/003

New high-pressure viscosity determinations of NaAlSi3O8-H2O liquids

Poe, B.T, Romano, C, Liebske, C, Terasaki, H, Rubie, D.C, Suzuki, A, Funakoshi, K

Bayerisches Forschungsinstitut für Experimentelle Geochemie und Geophysik Universität Bayreuth Annual Report 2003 141 - 144 2004年

The viscosity of CaMgSi2O6 liquid at pressures up to 13 GPa 査読

JE Reid, A Suzuki, KI Funakoshi, H Terasaki, BT Poe, DC Rubie, E Ohtani

PHYSICS OF THE EARTH AND PLANETARY INTERIORS 139 ( 1-2 ) 45 - 54 2003年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

The viscosity of CaMgSi2O6 (diopside) liquid has been determined up to 13 GPa and 2200degreesC using in situ falling sphere viscometry with X-ray radiography. The experiments were carried out in a 1500 1 multianvil apparatus at the SPring-8 synchrotron (Japan). A new, high-pressure sample assembly was developed with LaCrO3 replacing the traditionally used graphite furnace material, allowing experiments within the diamond stability field to be carried out. The viscosity of CaMgSi2O6 liquid increases slightly from 3.5 to 10 GPa and then decreases slightly at higher pressures. However, over the entire ranges of temperature (2030-2473 K) and pressure (3.5-13 GPa) investigated, variation in viscosity does not exceed +/-0.5 log units. The viscosity results from this study are consistent with those calculated from the pressure dependence of oxygen self-diffusion in CaMgSi2O6 liquid using the Eyring equation with a translation distance (lambda) of 0.45 nm providing the best correlation. Both sets of results indicate a change in pressure dependence at approximately 10 GPa, where viscosity results show a maximum with pressure and silicon and oxygen self-diffusivity results show a minimum. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0031-9201(03)00143-2

Determination of peridotite liquid transport properties at high pressure

Schmickler, B, Rubie, D.C, Liebske, C, Suzuki, A, Terasaki, H, Poe, B.T

Bayerisches Forschungsinstitut für Experimentelle Geochemie und Geophysik Universität Bayreuth Annual Report 2002 121 - 122 2003年

In situ viscosity measurements of albite melt under high pressure 査読

K Funakoshi, A Suzuki, H Terasaki

JOURNAL OF PHYSICS-CONDENSED MATTER 14 ( 44 ) 11343 - 11347 2002年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IOP PUBLISHING LTD

The viscosities of albite (NaAlSi3O8) melt under high pressures have been measured using an x-ray radiography falling sphere method with synchrotron radiation. This method has enabled us to determine the precise sinking velocity directly. Recent experiments of albite melt showed the presence of a viscosity minimum around 5 GPa (Poe et al 1997 Science 276 1245, Mori et al 2000 Earth Planet. Sci. Lett. 175 87). We present the results for albite melt up to 5.2 GPa at 1600 and 1700degreesC. The viscosity minimum is clearly observed to be around 4.5 GPa, and it might be explained not by the change of the compression mechanism in albite melt but by change of the phase itself.

DOI： 10.1088/0953-8984/14/44/479

Viscosity of albite melt at high pressure and high temperature 査読

A Suzuki, E Ohtani, K Funakoshi, H Terasaki, T Kubo

PHYSICS AND CHEMISTRY OF MINERALS 29 ( 3 ) 159 - 165 2002年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

The viscosity of albite (NaAlSi(3)O(8)) melt was measured at high pressure by the in situ falling-sphere method using a high-resolution X-ray CCD camera and a large-volume multianvil apparatus installed at SPring-8. This system enabled Lis to conduct in situ viscosity measurements more accurately than that using the conventional technique at pressures of up to several gigapascals and viscosity in the order of 10(0) Pa s. The viscosity of albite melt is 5.8 Pa s at 2.6 GPa and 2.2 Pa s at 5.3 GPa and 1973 K. Experiments at 1873 and 1973 K show that the decrease in viscosity continues to 5.3 GPa. The activation energy for viscosity is estimated to be 316(8) kJ mol(-1) at 3.3 GPa. Molecular dynamics simulations suggest that a gradual decrease in viscosity of albite melt at high pressure may be explained by structural changes such as an increase in the coordination number of aluminum in the melt.

DOI： 10.1007/s00269-001-0216-4

Viscosity change and structural transition of Molten Fe at 5 GPa 査読

H Terasaki, T Kato, S Urakawa, K Funakoshi, K Sato, A Suzuki, T Okada

GEOPHYSICAL RESEARCH LETTERS 29 ( 8 ) 10.1029/2001GL014321- 2002年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER GEOPHYSICAL UNION

[1] The in situ viscosity measurements of the pure molten Fe under high pressures were made by falling sphere X-ray radiography method. Viscosity coefficients at about 2000 K were 15-24 mPa s at 2.7-5.0 GPa, and 4-9 mPa s at 5.0-7.0 GPa. Drastic decrease was found at around 5 GPa, at which stable solid phase below the melting temperatures change from delta (bcc) to gamma (fcc) phases. The observation indicates the possibility that the structural change in the molten Fe occurs in a narrow pressure interval (1 GPa) at the similar condition with the phase transformation in the solid.

DOI： 10.1029/2001GL014321