and deposition of chemicals takes place when geothermal
fluids interact with the host rocks around the reservoir.
It is thought that the distribution of each geothermal
water (alkali-neutral Cl type hot water, acid SO4 type
hot water etc.) as well as its flowing path can be estimated
by the analysis of the chemical composition of main
and trace component of alteration mineral.
JEC joined forces with NEDO for the development of these
techniques aiming at secondary quartz or pyrite as measuring
probes and carrying out precision measurement using
the Inductively coupled plasma mass-spectrometer ICP-MS
The selection of these secondary quartz or pyrite minerals
is for the purpose of eliminating the influence rock
difference and that of the degree of geothermal alteration.
Secondary quartz and pyrite are depositions and crystallizations
of chemicals in the geothermal hot water. Therefore,
the changes of these secondary components (Fig. 6-2)
seem to show the difference of geothermal waters and
temperature. West JEC pursues to make use of this knowledge
to disclose the horizontal and vertical distribution
of the different reservoirs.