1991 年度実績報告書

超高圧実験による地球深部の構造とダイナミックスの研究

研究課題

研究課題/領域番号	01460052
研究機関	岡山大学
研究代表者	伊藤英司岡山大学, 地球内部研究センター, 教授 (00033259)
研究分担者	高橋栄一東京工業学, 理学部, 助教授 (40144779) 中村栄三岡山大学, 地球内部研究センター, 助教授 (80201672)
キーワード	地球中心核 / 地球進化 / 溶融鉄 / 融解けい酸塩 / シリコン / カリウム / スラブ / 超塑性
研究概要	前年度に引き続き、初期地球においてマグマオ-シャン中で生じた中心核の分離過程の実験的シミュレ-ションが行われた。高温高圧下での溶融鉄と融解けい酸塩の間のSi分配を、純鉄とMgSiO_3または(Mg_<0.9>Fe_<0.1>)_2SiO_4の混合物を出発物質として25GPaまで系統的に調べられた。また、従来から中心核の熱源としての重要性が指摘されていたKの挙動を純鉄とKAlSi_3O_8を出発物質にして26GPa、2500℃で検討した。その結果、Siの溶融鉄への溶解は15GPa程度の圧力で認められ圧力とともに増大することが明らかになった。すなわち融解けい酸塩と溶融鉄との間のSiの分配係数は27(15GPa)から6(26GPa)に減少すること、また分配係数の値は、融解けい酸塩の組成にあまり依存しないことが判明した。この結果を外挿すると1000km程度の深さのマグマオ-シャンの底では始源核物質に20%程度のSiが取り込まれ、コンドライト的なマントル組成がペリドタイト的なものに変わり得ることが示された。以上の結果をもとにして、中心核の進化とマントル最下部に存在するD"層の構成についてのモデルを提案した。Kについては溶融鉄中に最大の0.7%の存在が認められ融解けい酸塩との間の分配係数は48程度と見積られた。この値から推定される中心核のKの存在量は約5ppmであり、現在の発熱量は3×10^<10>W程度と見積られる。沈み込むスラブの下部マントルにおける力学的モデルを実験的に明らかにするためMn_2TiO_4から生ずるMnOとMnTiO_3の混合物について粒成長と流動特性を調べた。その結果、粒成長がT/Tm〜0.6程度の温度では著しく遅いこと、また混合物が超塑性的流動を示すことが明らかになった。

研究成果

(25件)

すべてその他

すべて文献書誌 (25件)

[文献書誌] Ito,E.&Katsura,T.: "Dissolution of silicon and oxygen in molten iron at high pressure and temperature" Proc.Jpn.Acad.67,B. 153-158 (1991)
[文献書誌] Ito,E.&Sato,H.: "Aseismicity in the lower mantle by superplasticity of the descending slab" Nature. 351. 140-141 (1991)
[文献書誌] Katsura,T.,Tsuchida,Y.,Tto,E.,Yagi,T.,Utsumi,W.,&Akimoto,S.: "Stability of magnesite under the lower mantle conditions" Proc.Jpn.Acad.67,B. 57-60 (1991)
[文献書誌] Kirkpatrick,R.J.,Howell,D.,Phillips,B.L.,Cong,X.ーP.,Ito,E&Navrotsky,A.: "MAS NMR spectroscopic study of Mg^<29>SiO_3 with the perovskite Structure" Am.Mineral.76. 673-679 (1991)
[文献書誌] Koibe,T.,Nakamura,E.,&Akimoto,S.: "Lead isotope analyses using multiーcollector mass spectrometer" I.S.E.I.Rept.,Ser.B,Okayama Univ.No.8. 1-21 (1991)
[文献書誌] Makishima,A.&Nakamura,E.: "Precise measurement of cerium isotope composition in rock samples" Chemical Geology(Isotope Geoscience). 94. 1-12 (1991)
[文献書誌] Makishima,A.&Nakamura,E.: "Faraday cup efficiency in a multicollector mass spectrometer" Chemical Geology(Isotope Geoscience). 94. 105-110 (1991)
[文献書誌] Makishima,A.,Nakamura,E.&Akimoto,S.: "Investigation of the bias in a secondary electron multiplien of Finnigan MAT 261 mass spectrometer for the quantitative analysis of rareーearth elements in rock samples" I.S.E.I.Rept.,Ser.B.,Okayama Univ.No.10. 1-19 (1991)
[文献書誌] Ming,L.C.,Kim,Y.M.,Manghnani,M.H.,UshaーDevi,S.,Ito,E.,&Xic,H.ーS.: "Back transformation and oxidation of(Mg,Fe)_2SiO_4 spinels at high temperature" Phys.Chem.Minerals. 18. 171-179 (1991)
[文献書誌] Ohtani,E.,Kato,T.&Ito,E.: "Transition metal partitioning between lower mantle and core materials at 27 GPa" Geophys.Res.Lett.18. 85-88 (1991)
[文献書誌] Ohtaka,O.,Yamanaka,T.,Kume,S.,Ito,E.&Navrotsky,A.: "Stability of nonoclinic and orthothombic zirconia:studies by highーpressure phase equilibria and calorimetry" J.Am.Ceram.Soc.74. 505-509 (1991)
[文献書誌] Osako,M.&Ito,E.: "Thermal diffusivity of MgSiO_3 perovskite" Geophys.Res.Lett.18. 239-242 (1991)
[文献書誌] Shibata,T.&Nakamura,E: "Interaction between subducted oceanic slab and wedge mantle inferred from acrossーarc variations of Pb,Sr and Nd isotopic compositions in northeastern Japan" Proc.Japan Acad.67. 115-120 (1991)
[文献書誌] 高橋栄一: "マントルの化学的非物質構造" 地震. 44. 217-232 (1991)
[文献書誌] Akaogi,M.,Kusaba,K.,Sukaki,J.,Yagi,T.,Kikegawa,T.,Yusa,H.&Ito,E.: "Highーpressure highーtemperature stability of α PbO_2ーtype TiO_2 and MgSiO_3 majorite:calorimetric and in situ Xーray diffraction study" HighーPressure Research:Application to Earth and Planetaty Sciecnces,eds.Y.Syono and M.H.Manghnani,Terrapub Tokyo/Am.Geophys.Union,Washington D.C.(1992)
[文献書誌] Brearley,A.J.,Rubie,D.C.&Ito,E.: "Mechanisms of the transformations between the α,β,and γ polymorphs of Mg_2SiO_4 at 900°C and 15GPa" Phys.Chem.Minerals. (1992)
[文献書誌] Hofmeister,A.M.&Ito,E.: "Thermodynamic properties of MgSiO_3 ilmenite from vibrational spectra" Phys.Chem.Minerals. (1992)
[文献書誌] Ishikawa,T.&Nakamura,E.: "Boron isotope geochmeistry of the oceanic crust from DSDPーODP Hole 504 B" Geochim.Cosmochim.Acta. 56. (1992)
[文献書誌] Ito,E.&Katsura,T.: "Melting of ferromagnesian silicates under the lower mantle conditions" HighーPressure Research:Application to Earth and Planetary Sciences,eds,Y.Syono and M.H.Manghnani,Terrapub,Tokyo/Am.Geophys.Union,Washington D.C.(1992)
[文献書誌] Ito,E.&Sato,H.: "Effect of phase transformations on the dynamics of the descending slab" HighーPressure Research:Application to Earth and Planetary Sciences,eds,Y.Syono and M.H.Manghnani,Terrapub,Tokyo/Am.Geophys.Union,Washington D.C.(1992)
[文献書誌] Katsura,T.&Ito,E.: "The system MgOーSiO_2ーCO_2ーH_2O:a preliminary investigation of concentration of CO_2 on the mantle fluid" HighーPressure Research:Application to Earth and Planetary Sciences,eds,Y.Syono and M.H.Manghnani,Terrapub,Tokyo/Am.Geophys.Union,Washington D.C.(1992)
[文献書誌] Kawasaki,T.&Ito,E.: "Exchange of Fe^<2+> and Mg^<2+> between olivine and clinopyroxene at 75 kbar and 1300°C" HighーPressure Research:Application to Earth and Planetary Sciences,eds,Y.Syono and M.H.Manghnani,Terrapub,Tokyo/Am.Geophys.Union,Washington D.C.(1992)
[文献書誌] Kudo,Y.,Prewitt.C.T.,Finger,L.W.&Ito,E.: "Xーray studies on(Mg,Fe)SiO_3 perovskite:Ionic radiiーbond strength systematics" HighーPressure Research:Application to Earth and Planetary Sciences,eds,Y.Syono and M.H.Manghnani,Terrapub,Tokyo/Am.Geophys.Union,Washington D.C.(1992)
[文献書誌] Nakamura,E.,Ishikawa,T.,Birck,JーL.&Allegre,C.J.: "Precise born isotopic analysis of natural rock samples using a boronーmannitol complex" Chemical Geology(Isotope Geoscience). 94. (1992)
[文献書誌] Yoshikawa,M.&Nakamura,E.: "Precise Isotope determination of trace Sr in magnesiumーrich samples" Chemical Geology. (1992)

1991 年度 実績報告書

超高圧実験による地球深部の構造とダイナミックスの研究

研究代表者

伊藤 英司 岡山大学, 地球内部研究センター, 教授 (00033259)

研究成果

[文献書誌] Ito,E.&Katsura,T.: "Dissolution of silicon and oxygen in molten iron at high pressure and temperature" Proc.Jpn.Acad.67,B. 153-158 (1991)

[文献書誌] Ito,E.&Sato,H.: "Aseismicity in the lower mantle by superplasticity of the descending slab" Nature. 351. 140-141 (1991)

[文献書誌] Katsura,T.,Tsuchida,Y.,Tto,E.,Yagi,T.,Utsumi,W.,&Akimoto,S.: "Stability of magnesite under the lower mantle conditions" Proc.Jpn.Acad.67,B. 57-60 (1991)

[文献書誌] Kirkpatrick,R.J.,Howell,D.,Phillips,B.L.,Cong,X.ーP.,Ito,E&Navrotsky,A.: "MAS NMR spectroscopic study of Mg^<29>SiO_3 with the perovskite Structure" Am.Mineral.76. 673-679 (1991)

[文献書誌] Koibe,T.,Nakamura,E.,&Akimoto,S.: "Lead isotope analyses using multiーcollector mass spectrometer" I.S.E.I.Rept.,Ser.B,Okayama Univ.No.8. 1-21 (1991)

[文献書誌] Makishima,A.&Nakamura,E.: "Precise measurement of cerium isotope composition in rock samples" Chemical Geology(Isotope Geoscience). 94. 1-12 (1991)

[文献書誌] Makishima,A.&Nakamura,E.: "Faraday cup efficiency in a multicollector mass spectrometer" Chemical Geology(Isotope Geoscience). 94. 105-110 (1991)

[文献書誌] Makishima,A.,Nakamura,E.&Akimoto,S.: "Investigation of the bias in a secondary electron multiplien of Finnigan MAT 261 mass spectrometer for the quantitative analysis of rareーearth elements in rock samples" I.S.E.I.Rept.,Ser.B.,Okayama Univ.No.10. 1-19 (1991)

[文献書誌] Ming,L.C.,Kim,Y.M.,Manghnani,M.H.,UshaーDevi,S.,Ito,E.,&Xic,H.ーS.: "Back transformation and oxidation of(Mg,Fe)_2SiO_4 spinels at high temperature" Phys.Chem.Minerals. 18. 171-179 (1991)

[文献書誌] Ohtani,E.,Kato,T.&Ito,E.: "Transition metal partitioning between lower mantle and core materials at 27 GPa" Geophys.Res.Lett.18. 85-88 (1991)

[文献書誌] Ohtaka,O.,Yamanaka,T.,Kume,S.,Ito,E.&Navrotsky,A.: "Stability of nonoclinic and orthothombic zirconia:studies by highーpressure phase equilibria and calorimetry" J.Am.Ceram.Soc.74. 505-509 (1991)

[文献書誌] Osako,M.&Ito,E.: "Thermal diffusivity of MgSiO_3 perovskite" Geophys.Res.Lett.18. 239-242 (1991)

[文献書誌] Shibata,T.&Nakamura,E: "Interaction between subducted oceanic slab and wedge mantle inferred from acrossーarc variations of Pb,Sr and Nd isotopic compositions in northeastern Japan" Proc.Japan Acad.67. 115-120 (1991)

[文献書誌] 高橋 栄一: "マントルの化学的非物質構造" 地震. 44. 217-232 (1991)

[文献書誌] Brearley,A.J.,Rubie,D.C.&Ito,E.: "Mechanisms of the transformations between the α,β,and γ polymorphs of Mg_2SiO_4 at 900°C and 15GPa" Phys.Chem.Minerals. (1992)

[文献書誌] Hofmeister,A.M.&Ito,E.: "Thermodynamic properties of MgSiO_3 ilmenite from vibrational spectra" Phys.Chem.Minerals. (1992)

[文献書誌] Ishikawa,T.&Nakamura,E.: "Boron isotope geochmeistry of the oceanic crust from DSDPーODP Hole 504 B" Geochim.Cosmochim.Acta. 56. (1992)

[文献書誌] Ito,E.&Katsura,T.: "Melting of ferromagnesian silicates under the lower mantle conditions" HighーPressure Research:Application to Earth and Planetary Sciences,eds,Y.Syono and M.H.Manghnani,Terrapub,Tokyo/Am.Geophys.Union,Washington D.C.(1992)

[文献書誌] Ito,E.&Sato,H.: "Effect of phase transformations on the dynamics of the descending slab" HighーPressure Research:Application to Earth and Planetary Sciences,eds,Y.Syono and M.H.Manghnani,Terrapub,Tokyo/Am.Geophys.Union,Washington D.C.(1992)

[文献書誌] Katsura,T.&Ito,E.: "The system MgOーSiO_2ーCO_2ーH_2O:a preliminary investigation of concentration of CO_2 on the mantle fluid" HighーPressure Research:Application to Earth and Planetary Sciences,eds,Y.Syono and M.H.Manghnani,Terrapub,Tokyo/Am.Geophys.Union,Washington D.C.(1992)

[文献書誌] Kawasaki,T.&Ito,E.: "Exchange of Fe^<2+> and Mg^<2+> between olivine and clinopyroxene at 75 kbar and 1300°C" HighーPressure Research:Application to Earth and Planetary Sciences,eds,Y.Syono and M.H.Manghnani,Terrapub,Tokyo/Am.Geophys.Union,Washington D.C.(1992)

[文献書誌] Kudo,Y.,Prewitt.C.T.,Finger,L.W.&Ito,E.: "Xーray studies on(Mg,Fe)SiO_3 perovskite:Ionic radiiーbond strength systematics" HighーPressure Research:Application to Earth and Planetary Sciences,eds,Y.Syono and M.H.Manghnani,Terrapub,Tokyo/Am.Geophys.Union,Washington D.C.(1992)

[文献書誌] Nakamura,E.,Ishikawa,T.,Birck,JーL.&Allegre,C.J.: "Precise born isotopic analysis of natural rock samples using a boronーmannitol complex" Chemical Geology(Isotope Geoscience). 94. (1992)

[文献書誌] Yoshikawa,M.&Nakamura,E.: "Precise Isotope determination of trace Sr in magnesiumーrich samples" Chemical Geology. (1992)

1991 年度実績報告書

伊藤英司岡山大学, 地球内部研究センター, 教授 (00033259)

[文献書誌] 高橋栄一: "マントルの化学的非物質構造" 地震. 44. 217-232 (1991)