Conclusions
X-ray CT visualizes internal structures of rock samples
- Miarolitic cavity, enclave, mafic and felsic minerals by
medical CT and microcrack by industrial CT
Large cavity zone develops in the direction of N20_E
- This trend is consistent with that of low-resistive zone
(NEDO, 1996) and isothermal contour at 500 m below sea level
(Tamanyu, 1994) and the hypocenter distribution of microearthquakes
in shallow depth from the Kakkonda granite (Uchida et al., 1996).
As the high-porosity zone such as the miarolitic cavity zone
may develop into the geothermal reservoir, the direction of N
20° E may be a trend governing the geothermal reservoir in the
Kakkonda geothermal field.
Three-dimensional shape analysis of miarolitic cavities
- The cavities are ellisoidal.
- Axial directions of ellipsoid are consistent with present
regional stress field in NE Japan which is E-W compressional
and reverse-fault type. This indicates that the cavities were
deformed under the stress field as same as present regional one
in NE Japan (Shimazaki et al., 1978).