The Takashima coal mine of the Mitsubishi Coal Mining Co., Ltd. is located at the Takashima Island, 15km to the southwest of the Nagasaki Harbour. The present mining faces are located in the offshore area 7km from the island. Annual production in the last 10 years averages to 700×10³ tons of mainly metal-lurgical coal.
The mine is located in the central part of the Takashima Coal Field. The coal bearing Palaeogene outcrops on the several islands, and in the offshore area where it is covered by unconsolidated Quaternary sediments. Based on the geological information on the islands and outcrops in the surrounding shallow water area, several coal mines were operated. The Takashima coal mine is only one operated at present among them. Although the mine has attempted various offshore geological and geophysical survey in the past, the data obtained was not sufficient enough for the long term mine planning. The Tobishima area is covered by 70-80m of sea water and the Palaeogene is overlain by Quaternary sediments of 100m in thickness.
In 1981, the Takashima coal mine applied the reflection seismic survey to the virgin field to estimate the depth of coal seams, delineate structural contours of coal seams and pick up tectonic faults. The survey resulted in detecting characteristic reflectours in the Palaeogene coal bearing formation. One of these was interpreted as the reflection from the main coal seams being mined out at present, based on a correlation with the mined out area and the bore hole drilling data. The depth contour map indicated that the main coal seams lay in the large area with minable depth, a low degree of dip and a few, small displacement by faults.
However, the seismic survey was not enough to obtain the information as to individual seam thickness and minor faults. Thus an offshore drilling was carried out in 1982 by a semi-submersible oil rig to determine seam thickness and coal qualities such as ash contents and coking properties in order to meet operation planning. Drilling programme was made based on the seismic section to drill the cover rock by non-coring bit and to drill the objec-tive coal seams by coring bit to minimize the drilling cost. The prognosed depth was so accurate that the whole coal seams as well as roof and floor rocks were cored successfully without a side track drilling.
The Takashima coal mine has succeeded by these surveys to discover new and large amount of coal reserves in the structurally favourable area neighbouring the present mining area. The reserves would contribute to the efficient mining operation in the near future.

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Microscopic textures and their mutual relationships in the kuroko ores from the Ezuri deposit are as follows:
1. A variety of textures in the ores constitute a systematic uni-directional evolution series, i. e., framboidal and botryoidal textures → concentric and banded colloform textures → euhedral to anhedral intergrowth textures. They provide information on the mineralization history at a conventional time scale.
2. The observed textural evolution series can be correlated with the sequence of metal deposition, i. e., Fe mineralization stage → Cu-Fe mineralization stage → Zn-Pb mineralization stage.
3. The Fe mineralization stage is characterized essentially by formation of framboidal pyrite, the Cu-Fe mineralization stage by the fixation of copper as bornite in addition to the continuous overgrowth of colloform pyrite, and the Zn-Pb mineralization stage essentially by the metasomatic fixation of sphalerite, galena and other accessary ore minerals onto the pre-existent Fe-Cu ores and also by the transformation of the pre-existent pyrite and bornite into chalcopyrite.

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Fluid inclusions of the Kawarage and Ugusu silicified bodies were studied, in connection with the basic study of the hot spring-type gold mineralization. The Kawarage silicified body is formed in Miocene dacitic tuff and intruded quartz porphyry, mainly due to leaching of rock-forming materials except silica through hydrothermal activity. The Ugusu silicified body occurs in Miocene and Pleistocene andesitic lava and tuff. Acid hydrothermal alteration zones are not formed extensively around the Kawarage body but widely around the Ugusu body. Besides devitrified glass inclusions, abundant secondary fluid inclusions are found in quartz grains of the altered rocks in the Kawarage silicified body. They are mostly gaseous and liquid inclusions, but saline polyphase inclusions are also rarely observed. The coexistence of gaseous and liquid inclusions in a cluster, which suggests boiling phenomena of hydrothermal solutions, is occasionally found throughout the body but more commonly in the marginal zone. Homogenization temperatures of fluid inclusions are distributed in a range between 180°C and 290°C, but most frequently in ranges of 220°-230°C, 250°-260°C and 270°-280°C. The lowest homogenization temperature of the inclusion cluster which shows boiling phenomena, varies from 215°C to 285°C, and the depth estimated from the lowest one among these temperatures, i.e. 215°C, is about 230m. Some clusters having different boiling temperatures occur in the same specimen. This suggests that intermittent boiling of solution took place at various temperatures during the hydrothermal activity. Samples preferable to the measurement of homogenization temperature of fluid inclusion are very few in the Ugusu silicified body. A temperature range between 195°and 305°C with a high frequency range at 240°-285°C, was determined on a single sample. Boiling phenomena were recognized in a temperature range of 295°-305°C. Homogenization temperatures of fluid inclusions in an alunite sample range between 205° and 220°C, with a high frequency peak at 210°C. It is presumed from the present result that the thermal conditions of silicification in the Kawarage and Ugusu silicified bodies were similar to those of the Nansatsu-type gold deposits, but the reason why gold mineralization is not known in these two areas remains unsolved.

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Sulfide minerals from some of the Carboniferous to Permian Kieslager-type deposits in eastern Chugoku and western Kinki district have been studied isotopically. Notwithstanding the differences in the age and acidity of host volcanic rocks, the studied deposits show a remarkble uniformity in sulfur isotopes, all δ³⁴S values falling in a narrow range from +0.6 to +2.9‰. This implies all the deposits studied have a common source of sulfur for sulfide minerals plausibly dominated by sulfur derived from a deep-seated origin. Barite samples from the Yanahara deposits are found to have δ³⁴S values of +12.1 to +15.1‰, which suggests the coeval sea water sulfate was the principal source for the barite.

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K-Ar age determination was made on a whole rock sample of the alunite-bearing silicified rock from the Iwato gold deposit, Kagoshima Prefecture, southern Japan. The sample is from one of the Nansatsu-type gold deposits, whose mineralization is characterized by the occurrence of leaching-type massive silicified rocks with gold dissemination. The result, 4.15±0.78 Ma, is interpreted to be the age of the mineralization at the Iwato gold deposit. It also suggests that the Nansatsu-type deposits were formed in close association with andesitic volcanism in the early Pliocene age.

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Contribution of Precambrian ore deposits to the production of base metals is very low in South America, as compared with those in other shield areas of the world. The situation might be considerably changed in future with increasing mineral potentials of the Brazilian shield, as exemplified by recent success in exploration for base-metal sulphide deposits in Central Brazil, the geotectonic setting of which is the primary concern of this paper.
Precambrian rocks in Brazil were formed and metamorphosed in five major, orogenic cycles; the Archean Guriense and Jequié, and the Proterozoic Transamazonian, Uruaçuan (Espinhaço), and Brazilian Cycles. The last one corresponds to the period of Pan-African tectonothermal events in Africa. Geologic setting of Archean and Early Proterozoic ore deposits of special metallogenic importance is briefly referred in relation to each tectonic province; e.g., the banded iron formation and copper deposits in the.Carajás Range, Caraíba copper deposits in granulitic pyroxenite, Boquira lead-zinc deposits in greenstone belt, the itabiritic iron formation and Morro Velho gold deposits in the Quadrilátero Ferrífero (Iron Quadrangle), and Late Proterozoic stratiform lead-copper, deposits at Perau mine.
In the Goiás Plateau of Central Brazil, the geotectonic evolution of Earlier Precambrian terrains has advancingly been elucidated by recent research and exploration activities to an extent that metallogenic consideration enables comparative study with other regions, and can benefit for future exploration. The Chapada copper-pyrite deposit has been discovered in Archean greenstone belt, and komatiitic peridotite and metavolcanic sequence of neighbouring greenstone belts are potential areas for nickel-copper and gold ores. Residual nickel deposits derived from Archean ultramafic granulitic terrain have been developed in the Niquelândia and Barro Alto complexes. The Americano do Brasil nickel-copper deposits of massive and disseminated ores occur in the layered intrusive of possible Early Proterozoic age. Stratiform copper-zinc deposits have been, explored at Palmerirópolis in the isoclinally folded volcano-sedimentary sequence of probable, Early Proterozoic age. Galena and sphalerite disseminations have been found in the Castelão area, yet unsuccessful, in the epicontinental carbonate formation of the Middle Proterozoic, which are quite similar in nature to lead-zinc deposits of the Mississippi Valley type in the Late Proterozoic Bambuí Group, that underlies the Vazante-Paracatú-Morro Agudo area and extends further east to cover the São Francisco craton.
Paleomagnetic reconstruction gives still uncertain configuration of the Proterozoic Gondwanaland. There are conflicting opinions on the existence of proto-South Atlantic ocean and possible operation, of the Wilson cycle between Brazilian and African continental segments during the periodd of Late Proterozoic.

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