Grant-in-Aid for Scientific Research (A)
|Allocation Type||Single-year Grants |
Petrology/Mineralogy/Science of ore deposit
|Research Institution||Tokyo Institute of Technology |
NAKASHIMA Satoru Tokyo Institute of Technology, Graduate School of Science and Engineering, Professor, 大学院・理工学研究科, 教授 (80237255)
KAWAMURA Katsuyuki Tokyo Institute of Technology, Graduate School of Science and Engineering, Professor, 大学院・理工学研究科, 教授 (00126038)
NAKAMURA Michihiko Tohoku University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (70260528)
丸山 茂徳 東京工業大学, 大学院・理工学研究科, 教授 (50111737)
|Project Period (FY)
2000 – 2003
Completed (Fiscal Year 2003)
|Budget Amount *help
¥47,820,000 (Direct Cost: ¥45,900,000、Indirect Cost: ¥1,920,000)
Fiscal Year 2003: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2002: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
Fiscal Year 2001: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2000: ¥39,500,000 (Direct Cost: ¥39,500,000)
|Keywords||Near Field Infrared Microspectrometer / Infrared microspectroscopy / Water in the crust and mantle / Volcanic glass / Grain boundary / thin film water Constrained "hard"water / 「かたい」水 / 変成岩中の水 / マントル物質 / 粒径 / 粒界の幅 / NaCl多結晶体 / 水溶液 / 減衰全反射赤外分光 / OH伸縮振動吸収帯 / NaCl / 炭酸 / 流体包有物|
In order to study the distributions and properties of water in the earth's interior, infrared microspectroscopic methods have been used to measure water in various crustal and mantle materials
1)Near-Field infrared Microspectroscopy
A new water characterization method has been developed by combining a near field microscopy spectroscopy. This and infrared Near-field infrared (NFIR) microspectroscopy can measure chemical states and contents of water down to about I wt% in submicron scale down to about 300nm. Mapping results by this NFIR method on microcrystalline quartz aggregates (agate) revealed constrained structures of water along grain boundaries with shorter hydrogen-bond distances.
2)Distribution of water in the crust and mantle materials
infrared microspectroscopy on various crustal and mantle rocks revealed the following distributions of water in the earth's interior.
a)Water in deep subducted metamorphic rock to the depth of about 200 km is distributed in defects in clinopyroxnes ar
id garnets with average contents of 2000 ppm, evidencing the water transport to the mantle.
b)Water in mantle can be stored in defects of mantle minerals such as perovskites upto about 2000 ppm. This is corresponding to 5 times as much water as the present sea water can be stored in the mantle.
c)Water in magma and erupted materials can be measured by infared microspectroscpy by using molar absorption coefficients determined by our studies. In-situ dehydration behaviors of magma can be studied also by this technique.
d)Fluids in shear zones in metamorphic rocks have contrasted wetting properties due to their chemistries (NaCl vs. C02) and this difference in wetting properties is expected to be much larger at metamorphic conditions.
e)Water in low grade metamorphic rocks is found to be distributed mainly ingrain boundaries.
3)Synthetic grain boundary water and synthetic aqueous solutions
In order to study experimentally the structures and properties of water in grain boundaries, several synthetic thin film water have been measured by infrared microspectroscopy. Thin film water showed a OH stretching absorption peak shift from 3400 to around 3200cm-1 indicating shorter hydrogen-bonding distance close to ice. Water sandwitched in minerals appeared to be constrained from about 200nm. This structural modification is dependent on mineral species and crystallographic orientations.
Synthetic aqueous solutions were studied by Attenuated Total Reflection (ATR) infrared spectroscopy, and NaCl solutions showed more loose nature with longer H-bond, while carbonate solutions indicated more tight nature with shorter H-bond. These aqueous solutions become "looser"at higher temperatues.
We organized an international symposium on September 13, 2003 in Tokyo Institute of Technology to discuss these results with international experts from physics, chemistry and earth sciences. The results of the symposium is now edited as a proceeding book which will be published in July-August 2004 (Nakashima, S.Mercury. L.Fenter, P. and Spiers, C.J.(2004)"Physicochemistry of Water and Dynamics_of Materials and the Earth-Structures and behaviors of the thin film water-"Universal Academy Press. Tokyo,〜200p.) Less