The effective exploration needs to get the geological data swiftly, and to analyze them quickly. The computer is the most powerful tool for this purpose. The followings are presented in this paper.
(1) The plane perpendicular to a folding axis has been calculated from bedding data (poles of bedding planes) by the least square method. The deviation of poles from the fitted plane gives the irregularity of the folding in a quantitative sense.
(2) The statistical analyses have proved that the low Na₂O is good indicater to detect an alteration zone in geothermal fields as well as an exploration area of kuroko-type ore deposits.
(3) The geostatistical method has been applied to the analysis of an fumarole activity, and revealed the geological structure, and given a reliable heat flow in the area.
(4) A color graphic display is powerful to recognize an assay pattern. It can show the relation among three elements on a two dimensional space.
(5) A computer algorism, by which the direction of principal stress axes are estimated from a fracture pair, makes the analysis of stress filed easy.
(6) An algorism to determine the monoclinal structure has been also presented. A couple of new aspects, allowance and uncertainity, are necessary for the determination.
(7) A handheld computer is available to describe and to resistrate rock samples or drilling cores at an explaration site.
For the more effective exploration, we must develop techniques of on-line measurements of geochemical, geological and petrological data, of operation researches on the exploration system, and of computer graphics including geological aspects.

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Recent exploration efforts in the Akenobe Mine has lead the discovery of Chiemon Vein Swarm in the South-western deeper levels of the mine. This vein swarm, consisting of more than forty blind veins, develops mainly below -10 level except No. 5 vein and is formed in the tension fractures of basic lava, basic tuff and slate of the upper Permian Maizuru Group.
No. 4 vein, the champion of the swarm, trends NW-SE and dips steeply to the north having strike and dip extension of over 470 m and 200 m, respectively. Most of the other veins, with lesser extension, follow almost similar NW-SE direction, and distribute around this champion vein as branch or parallel veins. Vein fractures are much more developed in basic lava of brittle nature, whereas they are less developed in basic tuff or slate of relatively ductile nature.
The occurrences of principal veins show multiple mineralization which are summarized into Cu-Zn, Sn-W and barren quartz from early to later stages.
Among these three stages, the distribution of Sn-W stage is limited in No. 4 Vein and Veins of its closest proximity.
Current ore reserve calculation from this vein swarm totalled about 1.6 million tons of minable ore, averaging 1.42% of copper, 5.75% of zinc and 0.34% of tin, and still this figure has a very good possibility of remarkable increase as the exploration goes on.
In addition, the discovery of this vein swarm proposed us a several new concepts on our exploraiton philosophy which would be extensively applied in the other area of the mine to disclose another blind vein swarms.

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The Kamaishi mine, located in northeastern Japan, is typical of skarn type copper-iron deposits. The Shinyama ore deposit, the largest one in the mine, consists of thirteen copper, copper-iron and iron orebodies. These are embedded in the skarn zones distributed along the rim of limestone of Carboniferous age and in diorite porphyrite belonging to the Ganidake igneous complex of early Cretaceous intrusion.
The recent exploration have been performed to discover high grade copper ores. The ore reserves confirmed between 1979 and 1984 were about 1.2 million tons. Especially we discovered the New No. 5 copper orebod, by tracing along the thrust fault separating the No. 2 and No. 3 limestones.
Its geological characteristics are as follows.
(1) The skarn is characterized by clinopyronexe, clinopyroxene-epidote, and epidote-garnet from limestone to diorite porphyry or slate. The copper mineralization is restricted within the clinopyroxene zone.
(2) It is divided into five unit orebodies called as V1, V2, V3, V4, and V5.
(3) The V1, V2 and V3 in the form of ore shoot are emplaced on the crest and east frank of the No. 3 limestone.
(4) The V4 and V5 extend toward north to south on the west frank of the No. 2 limestone.
(5) The former three resulted from the ore solution ascended along small geological structures bevelling the thrust fault, the latter two along it.
Further high grade ores are found around the New No.5 copper orebody by tracing and re-investigating the morphology of the limestone, diorite porphyrite and skarn as well as ores.

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The Mozumi deposits belong to skarn-type, and consist of many small ore bodies which are controlled by fissures. The forms of deposits are tabular and/or pipe-like, which appear to have been formed along the intersections of limestone beds and fissures. The main projects of this study are to clarify the structural relations between fissures and folded limestone beds and the zonal distribution of the deposits.
It might be called "vein-type replacement deposits". As the result of studies on relationship between fissures and mineralization, the important targets for exploration work were newly detected as follows:
(1) It seems that ore solution mainly ascended through fissures with NW trend, partly flowed into fissures with NS trend, and was finally deposited in the traversing limestone beds.
(2) Plunges of ore body are controlled by the intersections between the fissures and folded limestone beds.
(3) Distributions of Ag/Pb and Pb/Zn ratios in the ores indicate the trends of mineralization. As the result of following exploration, some promissing targets are confirmed as follows;
(1)"East-south ore zone" is discovered between"East zone" and "South zone" in the Nantohbu area of the Mozumi deposits.
(2) A large amount of ore is obtained in the East No. 5 deposit.
(3) Probability of huge amount of ore is surely expected at the deeper part of the Nantohbu area.

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Pyrometasomatic lead and zinc deposits of the Nakatatsu mine are embedded in skarn zones replacing the Fujikuradani Formation of the Paleozoic age.
The Nakayama skarn zone, located in the eastern portion of the mine area, is classified into hedenbergite zone, garnet zone and clinopyroxene-garnet zone. Despite changeful thickness of each zone, individual zone can be traced continuously in both lateral and vertical directions. They dip and strike concordantly with general structure of the Fujikuradani Formation.
The Nakayama ore deposit consists of many massive and bedded ore bodies. Most of them are localized in the hedenbergite zone. Especially rich ore bodies are developed in the hedenbergite zones adjacent to intercalated thin layers of slate and diabase. The shape of the ore bodies is also controlled by the structure of the thin layers.
These facts indicate that the mineralization of the Nakayama ore deposit was controlled by structure and mineral composition of the skarn, and that each ore body occurs to be controlled by presence and structure of the thin layers in the skarn zone.
Based on the conclusion of the studies, recent systematic exploration activities carried out in the Nakayama skarn zone have resulted in the significant discovery of several new ore bodies.

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It is pointed out by KuMITA et al. (1982) in the Shakanai ore deposits and KANBARA et al. (1984) in the Hanawa that the intrusion of post-ore dacites caused the deformation of the ore deposits. The present paper is to make clear the mechanism of the deformation of the Shakanai ore deposits, based mainly on the observation of the mode of occurrence of the ore deposits and their host rocks. The conclusions of this study are as follows;
(1) The deformations, such as folding and displacement, are observed in the ore deposits which overlie the convex surface of the gypsum zone. These deformations may be considered as a result of the upward expansion of the initial thick portion of the gypsum zone due to its volume increase by hydration of anhydrite.
(2) Intrusive dacites and hyaloclastic dacite lavas (MMD), occurring at the hanging wall and/or at the side wall of ore deposits, seem to have the ore deposits deformed in manners as displaced, steeply dipped, inverted, and folded. This activities are assumed to have taken place through the late Shakanai stage and the Sainokami stage.
(3) The size of MMD bodies around the No.11 ore body is maximum about 300m to 500m in diameter in plan. Seeing in cross-section, the shape of MMD body varies from flat one with low aspect ratio to ellipsoid one with high aspect ratio.
(4) MMD shows characteristic structure and texture according to the shape of its body. The flat body has a lamina-like structure concordant with its elongation. On the other hand, the ellipsoid one has a massive and breccia-like structure except on its marginal portion.

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Many studies have been carried out in the Kosaka area, eastern Hokuroku district. Recently the submarine caldera theory has been applied to explain the structural history of the Hokuroku basin. From this theoretical point of view, this paper makes analyses of the distribution of various sedimentary and volcanic units and restores original structures of the sedimentary basins in the Kosaka area.
The results are as follows.
(1) Geological evidence suggests that two calderas, the Kosaka caldera (3km×5km) and the Nagaki caldera (Ca. 4km×4km), were present in the Kosaka area. They belong to the Valles-type in the shape, but are different in the formation mechanism. For this reason, the new caldera model have been proposed, and named as the Hokuroku-type.
(2) The Kosaka kuroko deposits were formed at the center of the pre-kuroko volcanic eruptions in the Kosaka caldera.
(3) The ores of the Kosaka deposits were deformed by the extrusion of white rhyolite domes (D₃), and the intrusion of late stage dacite (D₀) and andesite bodies.
(4) Circular distribution of pre- and post-kuroko volcanics would have been controlled by the caldera structure.
These geological informations are very useful for the exploration of kuroko-type ore deposits.

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