FLUID INCLUSION MICROTHERMOMETRY AND GAS CHEMISTRY IN GEOTHERMAL SYSTEM, JAPAN AND ITS APPLICATION FOR THE STUDY OF FLUID EVOLUTION - Energy Research Developments: Tidal Energy, Energy Efficiency and Solar Energy - page 181

several investigators (Muramatsu, 1984, 1987; Komatsu and Muramatsu, 1994; Sasaki et al.,
1995; Muramatsu and Komatsu, 1996; Komatsu et al., 1998; Sawaki et al., 1999; Muramatsu
t al., 2000). The conceptual model of the Kakkonda geothermal system, and the gas evolution
and the origin of the reservoir fluid are discussed below as specific topics of the inclusion
studies of the field.
Characterization of the Upflow Zone
Based on the fluid inclusion study, the conceptual model of the Kakkonda geothermal
system is shown in figure 15 (Komatsu et al., 1998). The deep seated Kakkonda granite
intrusion (K-Ar ages of hornblende of 0.24 to 0.11 Ma) is a heat source of the Kakkonda
geothermal system (Doi et., 1998). The system is strongly controlled by fractures (Doi et al.,
1988), and the present reservoir fluid is flowing upward through the open space of the
fracture where hydrothermal minerals such as quartz were precipitated in the shallow
reservoir (Muramatsu and Komatsu, 1996).
Figure 15. Conceptual model of the Kakkonda geothermal system based on the fluid inclusion study
(Komatsu et al., 1998).