Abstract
Three-dimensional imaging of oriented granite cores from the borehole WD-1a, located at the Kakkonda geothermal field (Northeast Japan), was performed by a medical X-ray CT scanner. This paper confirms that X-ray CT is powerful tool for core observation because of (1) non-destructive observation, (2) rapid three-dimensional imaging and (3) easy operation. CT images display miarolitic cavities, felsic minerals, mafic minerals and en-claves inside granite cores. Three-dimensional distribution of miarolitic cavities can be constructed from CT im-ages and shows spatially heterogeneous development with the boundary which strikes 20°, and dips 55°to the NW. Because this trend is coincident with that of hypocenter distribution of microearthquakes, distribution of isothermal contour and resistivity gradient, these cavities may be related to the development of the Kakkonda geothermal reservoir.
