Attempts have been made to confirm the extension of geothermal reservoir by new techniques of exploration such as fluid inclusion survey and AE (acoustic emission) method in the Kakkonda (Takinoue) Geothermal Area.
It is necessary to estimate the borehole temperature for the evaluation of the geothermal resource of each well. The minimum homogenization temperature of the secondary inclusions in quartz and calcite is useful to make prediction of the underground temperature, because the minimum homogenization temperature is in good agreement with the measured downhole temperature by logging. In order to measure the temperature around fractures during drilling without delay, we developed a measuring apparatus for fluid inclusions in minerals without making polished sections ourselves, using a silicon oil-filled cell. The lateral distribution of the homogenization temperatures shows that high temperature zone exists in the northwestern part of the Kakkonda Area.
An acceleration-sensitive long-distance AE measurement technique has been successfully applied to study the behavior of fracture extension caused by a build-up test, hydraulic fracturing treatments and drilling. The increasing of reservoir pressure by a shut-down operation of production wells (build-up test) and hydraulic fracturing facilitates the fracture propagation, resulting in the generation of AE in the Kakkonda Area. When the AE measurements started in 1982, no AE had been generated in the D and E bases at the northwestern part in the Kakkonda until 1984. However, the AE sources distributed near the D and E bases in 1985. This fact means that fractures extend to the D and E bases by the build-up test and hydraulic fracturing. The fractures recognized by AE measurements are considered to be related to vertical type faults. The D and E bases were originally poor in permeable zones even though the existence of a few faults. However, a build-up test and hydraulic fracturing caused the fractures, and they propagated and connected with these faults.
It has been revealed on the basis of the new techniques of exploration described here that the geothermal reservoir in the Kakkonda Area extends to the northwestern part of this area. A 35% of production steam is now obtained around D and E bases.

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The Kushikino ore deposit is an epithermal gold-silver quartz vein type developed in Miocene to Pliocene andesites. Galena-clausthalite solid solution and altaite are abundant in the gold-silver-tellurium ores from the Shinpi No.1 vein of the mine; typical mineral associations are altaite-calaverite-clausthalite, altaite-electrum-galena, clausthalite-hessite-sylvanite, galena-petzite-sylvanite. Electron microprobe analyses were performed on the various associations in order to establish the limits of isomorphous substitutions among sulfur, selenium, and tellurium in the PbS-PbSe-PbTe series. Galena-clausthalite solid solution shows a compositional range from about 18 to 74 mol. percent PbSe, indicating a continuous solid solution series between PbS and PbSe. A rather wide miscibility gap exists between approximately 22 and 73 mol. percent PbSe in the PbSe-PbTe series, and a more extensive miscibility gap in the PbS-PbTe series. These compositional relations are explained from the viewpoint of geochemical character. No natural stable phase is expected to appear in a central part of the PbS-PbSe-PbTe system although the extent of the solid solutions is probably enlarged at elevated temperatures.

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Geology and fracture systems in the areas of Sado, Tsurushi and Ohtaki vein type gold deposits, Niigata Prefecture, were re-investigated and studied in detail. Based on the geologic information, some faults younger than vein fractures were dislocated to pre-fault situation on a cross section transversing the Sado deposit. As the result, a flexure became evident at the place where the Sado ore veins exist on the crose section.
On the other hand, simulation analysis was executed to construct a geologic structure model which formed the Sado, Tsurushi and Ohtaki ore veins. The simulation was carried out with Virtual Basement Displacement method which utilize three dimentional elasto-plastic finite element method.
Fracture systems which coincide with the ore veins were formed in the beds above steeply inclined basement in the experiment. The Sado ore vein systems, are best explained by the subsidence of experimental basement at northern part of east-trending line. As for the experimental basement below the Tsurushi ore vein system, northern part of west-northwest-trending line subsided, and as for the Ohtake ore vein systems, southern part of northwest-trending line subsided. These directions on the experimental basement appear to reflect the principal structure of the basement in this area.

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Survey on the relationship between the geologic structure and the ore vein patterns in Sapporp-Akaigawa district, southwestern Hokkaido, leads to the following conclusions.
(1) The Todoroki, Nakanosawa and Higashi-Kucchan vein systems were formed by the sinistral shear of E-W trend under the weak compressional stress field with maximum compressional stress axis of ENE-WSW direction at the latest Middle Miocene.
(2) The Toyohiro, Otoyo and Shin-Otoyo vein systems were formed under the tensional stress of ENE-WSW trend at the earliest Late Miocene.
(3) The Toyoha veins have been formed by the dextral shear with normal fault sense of E-W trend under the medium to weak tensional stress field of which maximum horizontal compressional stress axis has been WNW-ESE to NW-SE trend since the Late Miocene.
(4) The fracturing and the mineralization of the veins started simultaneously under control of the structural movement and the regional stress field for each of these deposits.

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A mass composed mainly of coarse-grained heterogeneous dioritic rocks is exposed between the Tochibora and Maruyama ore deposits in the Kamioka mining area. The rocks have gneissic texture and have been called "metabasite" in this mining area. The mass is emplaced in the Hida gneisses and thermally metamorphosed by the intrusion of granitic dykes. The dioritic rocks are made up mainly of plagioclase and greenish brown hornblende. An% of plagioclase ranges 31-34 in the coarse-grained diorite and 35-38 in the fine-grained part included in the coarse-grained one. Hornblende is mostly ferroan pargastic with ferro-edenitic margin. K-Ar age of hornblende separated from coarse-grained diorite is 192±6 Ma, which corresponds to K-Ar ages of hornblende from the Hida gneisses and Funatsu granites. This age represents the time of re-heating of the diorite by the intrusion of the Funatsu granites.

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