| Project/Area Number |
62045006
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| Research Category |
Grant-in-Aid for Overseas Scientific Survey.
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| Allocation Type | Single-year Grants |
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| Section | University-to-University Cooperative Research |
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| Research Institution | Akita University |
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Principal Investigator |
ISHIKAWA Yohei Mining College, Akita University, Professor, 鉱山学部, 教授 (00113887)
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| Co-Investigator(Kenkyū-buntansha) |
VOLBORTH Alexis Montana College of Mineral Science and Technology, Professor, 教授
BERG Richard B. Montana College of Mineral Science and Technology, Professor, 教授
MARUYAMA Takahiko Mining College, Akita University, Professor, 鉱山学部, 教授 (60006682)
OHGUCHI Takeshi Mining College, Akita University, Professor, 鉱山学部, 教授 (40006664)
HONDA Sakuro Mining College, Akita University, Professor, 鉱山学部, 教授 (50006631)
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| Project Period (FY) |
1987 – 1989
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| Keywords | Green Tuff region(Japan) / Bolder Batholith region(U.S.A.) / Submarine volcanism in middle Miocene age / Mineralization / kuroko deposits / Emery polymetallic vein-type mining district / Montana Tunnel diatreme-hosted gold deposit / Manganese mineralization |
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| Research Abstract |
This project was sponsored by the Monbusho International Scientific Research Program (University-to-University Cooperative Research). The Hokuroku ditrict, in the Green Tuff region of the northern Honshu, is one of the most produtive mining area in Japan. The Boulder batholith, one of the major Mesozoic granitoid batholiths of North America, is situated in the of western Montana. The batholith is the host rocks for the very large matal deposits. Our cooparative field surveys in Green Tuff and Boulder batholith regions have been made in 1987 and 1988. We have reached several conclusions described below.
1) Two stages are recongnized for the glauconite formation from Recent to Paleozoic age. The early stage is characterized with high Fe_2O_3, low K_2O and MgO contents. While, the latter stage is characterized by opposite contents during diagenesis.
2) The formation of Kuroko deposits are closely related to the late lava dome activity of a submarine single acidic volcanic cycle in the Nishikurosawa stage.
3) It is inferred that the increase of mixing ratio of sea water with ore fluids could contribute to the decrease of formation temperatures and sulfur fugacities through the Au to Pb-Zn minaralization satages at the No. 5 ore body of the the Nurukawa Kuroko Deposit, Aomori Prefecture.
4) Systematical observation of ore textures of Kuroko ores indicate that these morphologically researches are promoting new viewpoints of genesis of Kuroko deposits.
5) Changes of formation temperatures correspond to the progress of mineralization stages associated with multiple mineralization at the Mathhachi deposit of Jokoku mine, southwestern Hokkaido.
6) Based on the mineral assemblage, chemical composition of minerals and fluid inclusion studties the environment of ore fromation are estimated at the Montana Tunnel diatreme-hosted gold deposit and Emery Polymetallic vein-type deposit, Montana, respectively.
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