北海道勢多地域における低硫化系金鉱床の地質と探査
書誌事項
- タイトル別名
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- Geology and Exploration of the Seta Low Sulfidation Epithermal Gold Deposit, Eastern Hokkaido, Japan
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The Seta low sulfidation epithermal gold deposit is the most recently discovered gold deposit in Japan. The deposit is characterized by well preserved near surface hydrothermal activity features such as the presence of in-situ silica sinter, kaolin deposit, mercury deposit and hydrothermal breccias. These features were the clues for discovery of the deposit. The main mineralization zone is located at approximately 250 m below the present land surface, and a very shallow depth of gold mineralization is proposed.<BR>Mineralization occurs in two stages, (i) white crustiform quartz veins and (ii) black sulfide-rich breccia. Both types are hosted predominantly by tuff breccia and andesite lavas. The former at maximum reaches 19 m in core length and locally they may grade up to 50g/t. They formed from an ascending near neutral hydrothermal fluid. The veins in the north of the area are steep and has a NW-SE succession but at the south to southwest area, the veins become narrower and irregular and at the southernmost of the area, the veins become to be horizontal. This suggests that the hydrothermal fluids were restricted by the hydrostatic gradient when flowing from north to south. The latter exists in four parts and are oriented in a NW-SE trend forming an en-echelon pattern. Width reaches 25 m in core length but gold grade is generally low. It is proposed that it formed by mixing of following upwelling neutral hydrothermal fluid and low pH water percolating downwards from the aerated ground which were developed by condensation and oxidation of H2S rich steam accompanied by reduction of the watertable.<BR>BROWNE, P. R. L. and ELLIS, A. J. (1970): The Ohaki-Broadlands hydrothermal area, New Zealand: Mineralogy and related geochemistry: American Journal of Science, 269, 97-131.<BR>FOURNIER, R. O. (1984): Carbonate transport and deposition in the epithermal environment; In Geology and Geochemistry of Epithermal Systems, (BERGER, B. R. and BETHKE, P. M., eds.), Society of Economic Geologists, Society of Economic Geologists. Reviews in Economic Geology. Vol. 2, 63-72.<BR>GOTO, Y., NAKAGAWA, M. and WADA, K. (1995): Tectonic setting of the Miocene volcanism in northern Hokkaido, Japan: Speculation from their K-Ar ages and major element chemistry. Jour. Min. Petrol. Econ. Geol., 90, 109-123 (in Japanese with English abstract).<BR>Hokkaido Development Bureau (1991): Survey report on zeolite deposit in Kamishihoro. 37p (in Japanese).<BR>Hokkaido Development Bureau (1991): Survey report on a hot spring type gold deposit in Kamishihoro. 10p (in Japanese).<BR>KATAOKA, T.(1994): A study on the epithermal gold mineralization at the Seta area, Kamishihoro-cho, Hokkaido, B.Sc. Thesis, Hokkaido Univ., 74p (in Japanese).<BR>KATAOKA, T. (1996): A study on the characteristic features and the formation condition of epithermal gold mineralization at the Seta area, Kamishihoro-cho, Hokkaido, M. Sc. Thesis, Hokkaido Univ., 79p(in Japanese).<BR>KOSHIMIZU, S. and KIM, C. W. (1986): Fission-track dating of the Cenozoic formations in Central-Eastern Hokkaido, Japan (part II)-"Green tuff" in the Western-Central zone-. Jour. Geol. Soc. Japan, 92, 559-568 (in Japanese with English abstract).<BR>KIMURA, G., MIYASHITA, S. and MIYASAKA, S. (1983): Collision tectonics in Hokkaido and Sakhalin. In Accretion Tecton-ics in the Circum-Pacific Region (M. HASHIMOTO and S.Uyeda eds.), 123-134. Terra Sci. Pub., Tokyo.<BR>MAEDA, H. (1990): Mineralization ages of some epithermal gold-silver vein type deposits in the central Kitami mining district of the Kitami metallogenic province, Hokkaido, Japan. Mining Geol., 40, 17-22.
収録刊行物
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- 資源地質
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資源地質 47 (2), 45-58, 1997
資源地質学会
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詳細情報 詳細情報について
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- CRID
- 1390001204467878784
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- NII論文ID
- 130003645416
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- ISSN
- 21854033
- 09182454
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- データソース種別
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- JaLC
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