| Budget Amount *help |
¥2,150,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥150,000)
Fiscal Year 2007: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2006: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
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| Research Abstract |
1, From the deformation experiment of partially molten rock analogue, development of anisotropic microstructure under stress was demonstrated.
2, Viscous constitutive relations of partially molten rocks deforming in the regime of grain boundary (GB) diffusion creep are derived theoretically based on microstructural processes at the grain scale. The viscous constitutive relation developed in this study is based on contiguity as an internal state variable, which enables us to take into account the detailed effects of grain-scale melt distribution observed in experiments.
3, Compared to the elasticities derived previously for the same microstructural model, the viscosities are much more sensitive to the presence of melt and variations in contiguity. A very small amount of melt (<0.01) significantly reduces the bulk and shear viscosities, which has important implications for melt segregation dynamics.
4, A large viscous anisotropy is produced by anisotropy in contiguity, which occurs in deforming partially molten rocks.
5, With anisotropic viscosity, a direct coupling between shear and isotropic components of stress occurs and hence the role of shear deformation in melt migration significantly increases. We demonstrate the significant effects of viscous anisotropy on melt migration dynamics for two simple cases. First, in rotary shear deformation, an anisotropy creates a driving force for melt migration up stress gradients in the solid matrix. Second, in uniform simple shear deformation, melt segregates spontaneously into low-angle bands due to anisotropic melt alignment.
6, When applied to a simple approximation of flow in the mantle wedge of subduction zone, the anisotropic constitutive relation significantly affects melt migration patterns.
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