estimation of rock age (Fig.7-1) is done with the following
Assessment of the heat source location
location of the igneous rocks playing the role of
heat source for the geothermal system is estimated
assisted with the results of rock age determination
studies (K-Ar method, Fission Track method <F.T.>
or Thermo-Luminescence method <T.L.>).
(B) History of a
geothermal active area.
the T.L. method it is possible to estimate how the
most active part of the geothermal area migrates (Fig.7-2).
of the stratigraphy.
stratigraphy of disclosed by the well geology is confirmed
by rock dating data of each geological formation.
K-Ar and F.T. methods are mature techniques. Apart of
these methods it is necessary to develop a technique that
can determine rapidly the age of young alteration in rocks
in order to select the promising area within a geothermal
field where to drill production wells. For this purpose,
West JEC, in collaboration with NEDO, have developed and
successfully applied the alteration rock dating technique
using T.L. (Fig.7-3)