Abstract
Role of alteration minerals in geothermal exploration is discussed in reference with Matsukawa-type alteration found characteristically in Japan. In order to get exploration guids for the Matsukawa-type alteration, following three studies are desired from an engineering viewpoint.
(1) Mapping of the distribution of alteration minerals which is good indication to the permeability of geothermal fluids, with adequate data processing such as frequency analysis in which the cutting of short wave length is required.
(2) Study on the applicability of a reservoir model of White (1971) based on the idea that acid alteration solution is originated from saturated steam formed in deeper part. It should be inspected whether the alternative theory that, together with the saturated steam, magmatic emanation are also the sources supplying the alteration solution.
(3) Study on thermo-barometric condition of pyrophyllite-diaspore paragenesis characterizing the Matsukawa-type alteration in parallel with the comparison study to pyrophillite deposits of Cretaceous and Tertiary ages.
