Early Archean (3.5 Ga) hydrothermally altered greenstones from the Marble Bar area in the Pilbara craton, Western Australia, were investigated. Several successions of greenstone and hydrothermal bedded chert are exposed in this area. Greenstones in the study area are overlain by hydrothermal bedded cherts with a various thickness. The extensively altered greenstones are crosscut by massive chert veins that are considered as hydrothermal feeders. The greenstones are classified into two types based on its protolith; basalt and dolerite. The alteration mineral assemblage of dolerite (epidote+actinolite+chlorite+quartz+albite) indicates that the alteration condition was typical greenschist facies. On the other hand, the mineral assemblage of alteration minerals in basalts (carbonate minerals+K-mica+quartz+chlorite) implies that basalt was altered by the hydrothermal solution with high PCO₂ and K⁺ concentration. Carbonate minerals of basalt (calcite+ankerite+siderite) were developed by the seafloor hydrothermal alteration. Geological and mineralogical features of these. carbonatized greenstones lead us to propose that large amounts of carbonate minerals were precipitated by the submarine hydrothermal alteration and that carbonatization in the oceanic crust played an important role as a CO₂ sink in the early Archean atmosphere and ocean.

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Many vein type mineralization including the Kishu and Myoho deposits are known to occur in the southern and southeastern part of Kii Peninsula, where Middle Miocene volcanic products are underlain by the pre-Miocene and Miocene sedimentary complex of the Shimanto Belt. Vein type ore deposits that are related to felsic volcanism mainly occur in the Miocene sedimentary rocks except few in the pre-Miocene sedimentary rocks. Calcite veins are found with or without sulfide minerals in these sedimentary rocks. We have studied isotopic composition of the vein calcites in drilled cores obtained from these sedimentary rocks. The total ranges of δ¹⁸O and δ¹³C for calcites are from +6 to +17‰, and from -14 to -4‰, respectively. These value are divided into two groups based on their oxygen isotopic values: δ¹⁸O≤10‰ and δ¹⁸O>10‰, respectively. These data, together with homogenization temperature of fluid inclusions and strontium isotope data indicate that the relatively low δ¹⁸O value in calcites (δ¹⁸O<-10%0) formed under hydrothermal condition, however, the relatively high δ¹⁸O value in calcites (δ¹⁸O>10‰) formed from solution trapped in sedimentary rocks. The calcite veins with relative-ly high δ¹⁸O value are hosted mainly in the pre-Miocene sedimentary rocks, which suggests that the pre-Miocene sedimen-tary rocks might restrict free hydrothermal circulation. That resulted in lesser number of vein deposits in the rocks.

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The changes of the supply and demand of nonferrous metals including copper, lead and zinc from 1963 to 1996 in China are investigated based on the commodity statistics. These trends are correlated with the changes of the social and economic affairs in China. The mine production and refined metal production of these metals have been rapidly increasing since the middle of the 1980′s when the Chinese government carried out the administrative reform to organize the China National Nonferrous Metals Industry Corporation (CNNC) in 1983 and established the [China Law of Mineral Resources] in 1986. Much of lead and zinc produced have been exported, while copper has been deficient for the domestic demand in spite of the increasing production and the deficiency has been made up by import. The recent way of the foreign trade of nonferrous metals seen in China is characterized by the import of raw materials such as ores and concentrates (and scraps in case of copper) and by the export of primitively processed products such as refined metals. Although the mineral resource development has been promoted in China, there exist some problems on the actual spots. The Chinese nonferrous industries seem to lag behind in the respects of renewal of facilities, environmental conservation, etc. The illegal and disordered activities of the local mining groups are also a serious problem from viewpoints of mineral resource management and environmental conservation. The Chinese government has been performing an extensive reformation of national companies since 1993 to form modern industries and, in parallel with this, has issued some policies for the introduction of foreign capitals. The Japanese funds and advanced technologies are expected to contribute to the progress of the Chinese industries.

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We developed a software package entitled "SuperCritical for Windows^®" that is used for the thermochemical calculation of reactions between minerals and hydrothermal solutions in the temperature and pressure ranges of 0 to 1000°C and 1 to 5000bars, respectively. This package uses the databases of SUPCRT92 developed by Johnson et al. (1992)., however, the source code is newly encoded with Microsoft^® Visual Basic^® to be more suitable for the present PC environment and more user-friendly compared with SUPCRT92. This software package is composed mainly of two parts: one is for the calculation of the Gibbs energy of formation for minerals, fluids and aqueous species, and the other is for the calculation of the Gibbs energy of reactions among them. The output files are avilable as a text file in the CSV form or a worksheet (xis file) of Microsoft® Excel in order to facilitate the data processing and presentation of the calculation results.

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