Research Details

Outline

Research topics and methods

1. Microstructural observation of deformed rocks
                 + Evaluation of deformation mechanisms

　I observe microstructures of deformed rocks and evaluate grain morphologies and mineral distributions. The following images show microstructures by optical polarizing microscope (left) and backscatter electron mode of a scanning electron microscope (right) for regions composed of quartz and feldspar in a plastically deformed granitoid from an inner shear zone of the Ryoke Metamorphic Belt.
　I obtain information about deformation mechanisms, for example, by EBSD analysis. The following EBSD images show quartz in a brittly deformed granitoid from the Asuke shear zone. The region consists of fractured host grains and fine-grained quartz along fractures; microstructure by band contrast (left) and distribution of crystallographic orientations by color-coded Euler angles (right).

2. Mass change by development of deformation

　Rocks deform in the crust under different stress, strain rate, etc and different types of deformed rocks are formed. I measure mass changes associated with different types of deformation.

3. Determinations of rock deformation parameters

　I also perform deformation experiments mainly using solid-pressure-medium (Griggs-type) deformation apparatuses. I try to duplicate microstructures seen in natural samples. I also evaluate relationships between temperature, pressure, strain rate, stress, etc. as deformation parameters. Then, I try to understand deformation properties under actual conditions of the crust.

4. Evaluation of states and distribution of water in rocks and minerals

　Rocks and minerals include "water" in the forms of H₂O and-OH, both of which contribute to reactions and enhancement of deformation. I therefore evaluate states and amounts of water in rocks and minerals by using infrared spectroscopy.

5. Evaluation of water diffusivity in rocks and minerals

　Since water is ubiqitous in the crust, I evaluate water diffuvisity by experiments.

6. Observation of microstructural developments using rock analogues

In the deeper part of the Earth, rock textures can change over thousands of years. However, the processes occur very slowly in the deeper part and thus, we can not directly observe them. Therefore, we use organic materials as rock analogues and observe the real-time microstructural developments under a microscope. The following video shows an experiment using camphor as a rock analogue. The time speed is 200x faster. Now, we can replicate geological phenomena that would take thousands of years for natural rocks.