Several epithermal vein-type deposits accompany andesite lavas called "flat lava" in Sapporo-Iwanai district, northern part of southwest Hokkaido, which is situated at the junction between the northeast Honshu Arc and the Kuril Arc. These "flat lavas" have been dated to be of Pliocene and Pleistocene age by K-Ar method, and the compilation of Pliocene to Holocene lavas in the district has revealed a sequential alignment of three NW-SE volcanic chains of Early Pliocene, Late Pliocene and Pleistocene.
The mineralization ages of vein-type deposits such as Inakuraishi, Ohe, Toyoha and Koryu are coincident with ages of the "flat lavas" which overlie these deposits. This may imply that the magmatic activity resulted in the "flat lavas" was also concerned in generation of hydrothermal solutions which brought ore deposition. under the lavas.
These deposits are located at the intersection between the NW-SE volcanic chains and a E-W dextral strike-slip shear zone extended from the Kuril Arc. They are considered to have been formed since the Pliocene under the overlapped tectonic setting of the volcanism of the northeast Honshu Arc and the structural movement of the Kuril Arc. In this respect, the arc-arc junction may be one of the most suitable sites for vein-type mineralization.

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A number of tin-polymetallic deposits are distributed in the Eastern Cordillera of the Bolivian Andes. Ores produced from these deposits are divided into three main types from their age and mineral paragenesis: (A) tin and tungsten ore formed by the meso- to hypothermal mineralization of Mesozoic; (B) tin and base metal ore formed by the polymetallic mineralization in Miocene; (C) lead and zinc ore at the Matilde mine.
The sulfur isotopic compositions obtained from these ores have a wide range from -9.3 to 15.6 per mil. In the La Paz district (northern portion of the Eastern Cordillera), the range of δ³⁴S is from 0.0 to 15.6 per mil. Among them, the A-type ore has δ³⁴S values of 0.6 to 13.8 per mil, while δ³⁴S values obtained from the B-type ore are 0.0 to 15.6 per mil. The C-type ore from the Matilde mine shows δ³⁴S values between 10.9 and 14.6 per mil. The δ³⁴S obtained from the B-type ore in the Oruro-Potosi district (central portion of the Cordillera) is between -9.3 and 7.9 per mil. These values show remarkable distinction at the northern area (-9.3 to 0.4 per mil) and at the southern area (-2.0 to 7.9 per mil). The B-type ores from the Quechisla-Sur Lipez district (southern portion of the Cordillera) have δ³⁴S values between -7.9 and 3.9 per mil, which are similar to those obtained from the southern portion of the Oruro-Potosi district.
The isotopic geothermometry using sphalerite-galena pairs shows rather good agreement with homogenization temperature of the fluid inclusions. Thermochemical caluculation shows that sulfide minerals of these ore deposits had precipitated from the solution in which dominant sulfur species is H₂S. The δ³⁴S values of sulfide minerals correspond to those of bulk isotopic composition in the ore-forming fluid. The wide range of δ³⁴S value can not be explained that the sulfur was derived from a single source. Regional characteristic of sulfur isotopic composition suggests that a part of sulfur was derived from the country rocks. Besides the sulfur of deep seated origin, the biogenic sulfide sulfur in sedimentary rocks, and sulfur which was derived from sulfate minerals near the paleo-surface were responsible for the ore formation.

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Studied are elliptic plates sliced from a columnar black ore mass, collected from the eastern wall of the Tsutsumizawa open pit of the Hanaoka mine in 1960. The plates consist of barite, sphalerite and galena, with small amounts of colloform pyrite and euhedral bipyramidal quartz. Concentric mineral zoning of the plates with finegrained barite rim and porous center with a hole, suggests that the original columnar mass is a chimney from which Kuroko-forming hydrothermal solution vented. Sulfur isotope ratios of sulfide sulfur and sulfate sulfur are consistent with those reported for typical Kuroko deposits. The specimens confirm the occurrence of chimney structure at least at some parts of Kuroko formation, like those observed at the present active venting sites on the sea floor.

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Diffusion of iodide anion in rock pore water and its relation to porosity and pore structure were investigated in order to evalute diffusivity of "non-sorbing" radionuclides in various rock matrix. Porosities and pore-size distributions of various rock samples (diameter: 20 or 40 mm, length: 5 mm) of siliceous sedimentary rocks, andesites, schists, limestone, sandstone hornfels, granites and tuffs were measured by the water saturation method and the mercury intrusion porosimetry. The water saturation porosity ε _w of these rocks varied from 0.1 to 48% and is considered to be close to the total porosity ε _tot. The mercury intrusion method is considered to measure the pores larger than 5nm and might give the porosity em close to the transport porosity ε _tra.
The mercury porosimetry method provided pore-size distribution data of the rocks and they can be classified into two types: type-A has mainly larger pores from micro to nano pores and type-B has mainly pores smaller than 25 nm (nano and sub-nano pores).
Effective diffusion coefficients De of iodide anion for these water-saturated rocks were measured at room temperature using a simple diffusion cell, and their relation to the porosities ε _tot. and ε _tra. were studied. D _e and _tra. have a rough linear correlation D _e=5.3×10 ^-10 ε _{tra. tra.} ^1.3 in a logarithmic diagram for most of the rocks. This relation is very useful to estimate effective diffusivities of ions in various rock matrix.

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Epithermal gold deposits in Japan may be divided into Se-and Te-types. The Se-type occurs in sedimentary and volcanic rocks, while all deposits of the Te-type formed in volcanic rocks. The Se-type is accompanied by Ag, Pb, Zn and Mn mineralization, while the Te-type is, associated with Cu and Bi, and rarely Hg and Tl. The Se-type is characterized by the presence of large amounts of adularia, sericite, and carbonates but lacks barite. The Te-type is characterized by the presence of barite, sericite, and absence of carbonates. Cu minerals such as enargite are common and Bi minerals such as bismuthinite occur in the Te-type but Cu minerals are rare and there are no Bi minerals in the Se-type. Sericite alteration is common in Te-type gold mining districts, while propylitic and potassic alterations dominate in Se-type gold mining districts. Fluid inclusion data indicate that the Te-type and Se-type formed over temperature ranges of 200-300°C and 150-270°C, respectively. δ³⁴S of sulfide sulfur for the Se-and Te-types are -8 to +5‰ (av. 0‰) and -3 to +7‰ (av. +2 to 3‰), respectively, indicating an igneous source of sulfide sulfur for the Te-type and igneous and sedimentary sources for the Se-type. δ³⁴S of sulfate sulfur for the Te-type is in the range of +18 to +29‰, suggesting a contribution of SO₂ gas of volcanic origin. Sulfur and oxygen activities of ore fluids for the Te-type may have been higher than those for the Se-type, while the pH of ore fluids for the Te-tvpe is estimated to have been lower than that for ore fluids of the Se-type.
These geologic, mineralogic and geochemical characteristic features and a comparison of these features with those of active geothermal systems accompanied by epithermal-style mineralization indicate that (1) the Se- and Te-types formed in two different parts of same geothermal system, (2) the Te-type formed closer to the heat source than the Se-type, (3) the Te-type formed at a mineralization site further from the volcanic center than acid-sulfate-type and (4) contribution of SO₂ gas of volcanic origin and the type of host rocks are important factors in causing of the differences in the chemical nature (oxygen activity, sulfur activity, pH, sulfur isotopic compositions) of ore fluids responsible for the formations of the Te- and Se-bearing epithermal gold deposits in Japan.

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