| Project/Area Number |
13852005
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| Research Category |
Grant-in-Aid for Scientific Research (S)
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| Allocation Type | Single-year Grants |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | Okayama University |
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Principal Investigator |
ITO Eiji OKAYAMA UNIVERSITY, Institute for Study of the Earth's Interior, Professor, 地球物質科学研究センター, 教授 (00033259)
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| Co-Investigator(Kenkyū-buntansha) |
KATSURA Tomoo OKAYAMA UNIVERSITY, Institute for Study of the Earth's Interior, Associate Professor, 地球物質科学研究センター, 助教授 (40260666)
YONEDA Akira OKAYAMA UNIVERSITY, Institute for Study of the Earth's Interior, Associate Professor, 地球物質科学研究センター, 助教授 (10262841)
KANZAKI Masami OKAYAMA UNIVERSITY, Institute for Study of the Earth's Interior, Associate Professor, 地球物質科学研究センター, 助教授 (90234153)
WALTER J. Micheal 岡山大学, 固体地球研究センター, 教授 (20284094)
久保 敦 岡山大学, 固体地球研究センター, 日本学術振興会特別研究員
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| Project Period (FY) |
2001 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥100,100,000 (Direct Cost: ¥77,000,000、Indirect Cost: ¥23,100,000)
Fiscal Year 2004: ¥22,360,000 (Direct Cost: ¥17,200,000、Indirect Cost: ¥5,160,000)
Fiscal Year 2003: ¥22,360,000 (Direct Cost: ¥17,200,000、Indirect Cost: ¥5,160,000)
Fiscal Year 2002: ¥22,360,000 (Direct Cost: ¥17,200,000、Indirect Cost: ¥5,160,000)
Fiscal Year 2001: ¥33,020,000 (Direct Cost: ¥25,400,000、Indirect Cost: ¥7,620,000)
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| Keywords | the Kawai-type apparatus / sintered diamond / GaN / Fe_2O_3 / magma ocean / Mg perovskite / Ca perovskite / single crystal / 下部マントル / 熱弾性的性質 / 高圧含水相 / 川井式装置 / 63GPa発生 / 相平衡 / 溶融実験 / ペロフスカイト / 電気伝導度 / 弾性定数 / 焼結ダイアモンド / マグマオーシ / 高圧安定含水相 / 放射光 / 球共振法 / MORB / 鉄の相図 / 高温高圧ラジオグラフィー |
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| Research Abstract |
We have established a technique to generate pressure up to 60 GPa over a specimen volume 2 mm^3 within a repeatable accuracy of 2% using the Kawai-type multi anvil apparatus equipped with sintered diamond cubic anvils with edge length of 14 mm and a truncated corner of 1.5 mm. The maximum pressure reaches higher than 63 GPa. We carried out determination of phase equilibria of several materials under high-pressure and high-temperature by means of in situ X-ray observation using synchrotron radiation at Spring-8. First we examined iron up to 44 GPa and 2100 K. The stability of β-Fe was excluded, and the phase boundary for the ε【tautomer】γ transition was established. We further studied the phase equilbria of GaN and Fe_2O_3 up to 62GPa/900K and 58GPa/1400K, respectively, together with measurement of electrical resistance at 300 K. In GaN, the wurtzire-rocksalt transition was observed at 54GPa/300K and 51.5GPa/750K, suggesting the phase boundary with a negative slope. It was confirmed that
… More
Fe_2O_3 hematite (phase I) transforms successively into Rh_2O_3II type (II) and an orthorhombic phase (III) with increasing pressure. Both the phase boundaries for the I【tautomer】II, II【tautomer】III have negative slopes. The electrical resistance of GaN was in several tens of mega ohms up to 62 GPa and did not show any remarkable change on the wurtzite-rocksalt transition. The electrical resistance of Fe_2O_3, on the other hand, decreased monotonically from several hundreds mega ohms at 0 GPa to a few ohms at 58 GPa. However, the decrease over a pressure range 54±1 GPa was characteristically abrupt, ca. four orders of magnitude, which can serve as a new pressure fixed point.
In order to simulate material fractionation in a magma ocean formed in the early stage of the Earth, we performed melting experiments on peridotite and CI mantle material up to 35 GPa. In peridotite the first liquidus phase changes from feropericlase (Fp) to Mg-perovskite (Mg-Pv) and at 33 GPa liquidus Mg-Pv is successively followed down temperature by Fp and Ca-perovskite (Ca-Pv) within a small temperature interval. In CI mantle material, Mg-Pv is also the liquidus phase followed down temperature by Ca-Pv. These results suggest fractionation of both Mg-Pv and Ca-Pv in a deep magma ocean resulting in formation of a perovskite layer in bottom of the mantle. The layer may be a geochemical reservoir due to the high capability of Ca-Pv to accommodate large cations such as alkaline and rare earth elements.
We have successively synthesized single crystals with mm size of deep mantle materials such as Mg-Pv. These crystals are to be used for measurements of elasticity and various transport phenomena such as element and thermal diffusivilitisand electrical conductivity. Less
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