The Waisoi deposits are located 30km north west of Suva (the capital city of Fiji). The Waisoi deposits composed of the Waisoi East and Waisoi West deposits are porphyry-type copper deposits. In this prospecting area, core drilling of 10 holes, total 3, 192.55m, was carried out in 2003 for exploration of middle to high grade copper ore body. Based on the results of this survey, the characteristic of mineralization in the Waisoi deposits was confirmed as follows;
(1) All of 10 drill holes have intersected copper mineralization zone of more than 1.0% copper grade. Among them, remarkable copper mineralization were observed in 5 holes. The results of chemical analysis of prospective holes are as follows. Waisoi East deposit:
Drill hole NWS-3: Cu 0.85%, Au 0.41g/t, ECu: 1.06% (from 12.00 to 156.00m, 144m interval)
Drill hole NWS-10: Cu 0.89%, Au 0.64g/t, ECu: 1.21% (from 93.00 to 267.00m, 174m interval)
Waisoi West deposit:
Drill hole NWS-6: Cu 0.78%, Au 0.42g/t, ECu: 0.99% (from 243.00 to 440.00m, 197m interval)
Drill hole NWS-7: Cu 0.94%, Au 0.60g/t, ECu: 1.24% (from 273.00 to 339.00m, 66m interval)
Drill hole NWS-8: Cu 0.91%, Au 0.46g/t, ECu: 1.14% (from 33.00-174.00m, 141m interval)
The result of the drilling program, low angle holes with vertical direction of dominant fractures in Waisoi East deposit indicated more than 20% higher grade than other old vertical holes. This suggests possibility of major improvement of grade, which was reported by previous licence holders.
(2) Conceptual model of copper mineralization in the Waisoi deposits are established.
In the Waisoi East Deposit, the centre of mineralization can be characterised by the bornite-chalcopyrite mineral assemblage. The ore body seem to be developed in Wainimala Group, especially around the margin of the quartz porphyry, which is located in the centre of Waisoi East Deposit. From the results of microscopic observation, rock chemistry and fluid inclusion microthermometry, the ore mineralization with bornite-chalcopyrite mineral assemblage and strong potassic alteration probably occurred in the early stage by magmatic fluid with high temperature(>500°C) and high salinity. After this early stage mineralization, chemical and physical condition of ore fluid was changed by circulation along fractures in the quartz porphyry and in its marginal part, and phyllic alteration was formed associated with pyrite-chalcopyrite precipitation in the later stage at lower temperature.
In the Waisoi West Deposit, the centre of mineralization can be characterised by the bornite-chalcopyrite mineral assemblage accompanied by strong silicification and/or quartz vein stockwork and the mineralization is mainly related to the diorite porphyry which is located in the central part of Waisoi West Deposit. The shape of the ore body is seemed to be controlled by ENE-WSW and NW-SE trending fracture system developed around diorite porphyry. Early mineralization with bornite-chalcopyrite assemblage and potassic and phyllic alteration probably occurred in the early stage by magmatic fluid with high temperature(>500°C) and high salinity. It formed strong silicification and quartz vein stockwork in and around diorite porphyry. In the later stage, phyllic and argillic alteration which was formed associated with pyritechalcopyrite precipitation took place.

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Although the electric power generation using geothermal energy is classified as renewable energy, in the process to reach some renewable level of production there is often a considerable decline in steam production, and it causes an economical problem at several geothermal power plants in the world, including Japan. In the Okuaizu geothermal field in Fukushima prefecture, The Yanaizu Nishiyama Geothermal Power plant of the Tohoku Electric Power Company started operating by 65MWe in 1995, and Okuaizu Geothermal Co., Ltd. produces the steam used by this operation. Despite the fact that the steam production decreased in 2000 soon after the production had started, which caused the power generation output to fall until 38MWe, it succeeded in recovering up to 45MWe by now. From now on, it is needed to take measures that do not let the electric power to go below 45MWe. On the whole, the production decline trend of the Okuaizu geothermal field as well as almost all the geothermal fields in the world is to be harmonic trend. However, since a complicated factor is involved in each geothermal well, in many cases, a decline trend cannot be approximated with exponential or harmonic function curve. That the natural decline curve accompanying the pressure fall of the whole reservoir, as well as the decline or the increase curve by temporary cause and the overlap that is peculiar to each well make prediction more difficult. The writer examined the decline curve of each well in the Okuaizu geothermal field and concluded that there are three typical curves in this field: (1) the parabola decline curve by the physical blockade in the well bore by carbonate or sulfate scale, (2) the sharply irregular trend by the physical blockade of the geothermal fluid passing in the reservoir by mud water and cuttings and (3) the harmonic decline curve accompanying the pressure fall of the whole reservoir. The measure for the case (1), which is the well bore stimulation using hydrochloric acid was done successfully. For the case (2), which is the well bore stimulation using river water, was done with fruitful result. Enhanced Geothermal Systems, which means injecting water into the reservoir, are going on of preliminary tests as the measure for the case (3); the return current is not recognized yet.

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Since 2001, Nittetsu Mining has been carrying out copper exploration activities in twenty-two promising areas in Northern Chile, which were extracted using ASTER image analysis. In these areas, Furano area in Region I has been selected as the most important target considering its high mineral potential inferred from the ASTER image analysis and its easy access.
Furano area, covering 282km², locates some 15km northwest of Cerro Colorado copper mine. Geology of the basement rocks mainly consists of lower Cretaceous andesite and Paleogene intrusive rocks. They are widely covered by ignimbrite and alluvium sediment of Tertiary to Quaternary age. The RC drilling program of 13 holes, totaling 3, 704m, was carried out on the prospective locations in the western part of the project area, which were selected by geological and geochemical surveys. Dominant copper and gold mineralizations were observed in some holes. Above all, a tourmaline breccia zone in silicified andesite showed average copper grade of 0.9% over the depth from 110m to 190m in one hole. The ore body shows 40m in width, dipping 55 degrees towards north, and is expected to be 400m continuation from the distribution of surface mineral occurrences. About 20 million tons of ore reserve was estimated above the depth of 300m. In another hole, drilled in ignimbrite-covered area, oxidized and corroded tourmaline breccia and underlying chalcopyrite-disseminated granite porphyry were observed. A secondary precipitation of chalcocite was also recognized in the lower part of the tourmaline breccia. These evidences suggest that the adjoining area covered by ignimbrite still has high potential for porphyry copper deposition. Additional drilling exploration is required around those holes.

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The Japan International Cooperation Agency (JICA) and the Metal Mining Agency of Japan (MMAJ which reorganized the Japan Oil, Gas and Metals National Corporation) conducted a mineral exploration project surround the Baoule and Banifing Basin, the republic of Mali for eleven years since 1991.
Lateritic deep weathering is well developed throughout the project area. We estimated degree of lateritization by multi-element analysis and selected in situ geochemical anomalies by using regolith-landform map. Because Arsenic has close affinity for Fe-oxides, we used As/V ratio to distinguish arsenic enrichment derived from gold mineralization. As a result of pitting and RAB drilling conducted in the area where in situ Au and As/V ratio were overlapped, two gold mineralization zones were delineated.
The Siriba-Sobara gold mineralization zone is hosted in two mica granite and distributes 100-350m ×900m with NW-SE direction. This mineralization accompanies with Bi, As and W. Another Batouba gold mineralization zone is hosted in both meta-sediment and granite. This mineralization is heterogeneous and accompanies with Bi, Cu and Sn.

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The reliability of the thermodynamic dataset of SUPCRT98 (revised SUPCRT92, Johnson et al., 1992) was checked by calculating mineral saturation indices for geothermal waters. For comparison, the calculation was also conducted using the thermodynamic dataset of SOLVEQ86 (revised SOLVEQ, Reed, 1982). New computer code (GEOMS) was written using Visual Basic (ver.6.0). In order to calculate the mineral saturation indices, mass-balance equations and mass-action equations are solved in a successive iteration method. Total ionizable hydrogen ion (TOTH) was used as a mass balance for hydrogen ion.
Judging from the consistency of the calculation results with the field evidences, the dataset of SOLVEQ86 is considered to be unreliable in the temperature range of 170 to 300°C. On the other hand, the thermodynamic dataset.of SUPCRT98 was judged to be more reliable in the same temperature range. In the calculation of mineral saturation indices, attention should be paid to the aluminium concentration in geothermal waters because the aluminium concentration makes a large effect in the calculation results of mineral saturation indices.

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A computational model of global strontium cycle in the late Cenozoic (Neogene) has been built up. It is used for evaluating the influence of the weathering in the HTP (Himalayan and Tibetan Plateau) region due to the uplift and denudation and that in high-latitude area due to the glaciation on the increase in seawater ⁸⁷Sr/⁸⁶Srr in the late Cenozoic. The results indicate that (1) approximately 30% of the increase in ⁸⁷Sr/⁸⁶Srr of seawater can be explained by the HTP weathering, which is substantially influential as compared to its small area;(2) however, the ⁸⁷Sr/⁸⁶Srr fluctuations of silicate weathering in the region except the HTP region could be partially attributed to the weathering in high latitude especially the Antarctica;(3) the correlation between this ⁸⁷Sr/⁸⁶Srr variation and δ¹⁸O variation is identified in from the late Oligocene to the early Miocene and the Pliocene to the present, whereas the correlation is not confirmed in from the middle to late Miocene.
This discrepancy may be partially derived from uncertainty of estimation of the HTP uplift and the ⁸⁷Sr/⁸⁶Srr variation in the region except the HTP and high-latitude areas. The critical problems in attributing the increase in seawater ⁸⁷Sr/⁸⁶Srr to the weathering in high-latitude area might be low temperature and water availability. The former could be overcome by the previous studies of dependence of weathering rate and temperature, but the water availability in high latitude might have varied with time. Because low water availability has been presumed since late Miocene by previous studies, the above disagreement in from the middle to the late Miocene might be identified.

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In northwestern part of Honshu, Tertiary granitoids with 13.9 to 6.0 Ma age data, that is thought to be in a period of vein type mineralization, show the intermittent distributions in NE-SW and NW-SE trend. It suggests that the granitoids intruded along shear zones formed by common maximum compressive stress in E-W trend. Veins are hosted in E-W, NE-SW, NW-SE trending normal and reverse faults, NE-SW trending right lateral faults and E-W trending extension fractures. The normal and reverse faults were formed by intrusions of the granitoids and propylite. These might be re-opened fractures after being formed by the regional stress field based on their strikes. The right lateral faults in the propylite and extension fractures in the granitoids and propylite were formed by the regional stress field after the intrusive activities.

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The close association of basalts, bedded ferromanganese ore and red cherts is observable at the Kawame Quarry in the Hayachine Belt. Major, trace and rare earth element contents and chemical compositions of constituent minerals were determined for these three types of rocks. The basalts are composed of chlorite, albite, epidote, quartz, calcite, sphene, pumpellyite and actinolite, and locally preserve primary clinopyroxene relicts. The chemical compositions of these clinopyroxene relicts are generally similar to those of modern mid-ocean ridge basalt (MORB). In addition, bulk-rock chemical compositions of the basalts show that there is a general similarity between the Kawame basalts and modern MORB. The chondrite-normalized rare earth element (REE) patterns of the basalts are subtly light REE-enriched, suggesting the basalts appear to have an affinity for enriched MORB.
The ferromanganese ores are dominated by hematite with minor amounts of quartz. They exhibit significant enrichment of Fe, Mn, P, V, Y and REE except for Ce. There is a gross positive correlation between Fe+Mn and these enriched elements. The average pattern of these elements/Fe ratios of the ferromanganese ores is similar to that of modem hydrothermal metalliferous (ferromanganese) sediments near MOR. The Post-Archean Average Australian Shale-normalized REE patterns of the ferromanganese ores are characterized by negative Cc anomalies. Their geochemical features mentioned above demonstrate consistently that the Kawame ferromanganese ores are ancient counterparts of modem MOR hydrothermal sediments. Red cherts comprise of quartz and hematite with trace calcite, rhodonite, stilpnomelane, apatite, actinolite and andradite. They are simple mixtures of ferromanganese ores and pelagic cherts in varying proportions. In conclusion, the Kawame basalts associated with ferromanganese ores and red cherts are most likely remnants of late Devonian oceanic crust.

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