1996 Fiscal Year Final Research Report Summary
Ore textures and mineralization processes of seafloor deposits formed by hydrothermal circulation-Comparative study of the recent seafloor hydrothermal mineralization and Kuroko-type ore deposits-
| Project/Area Number |
07640633
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | Akita University |
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Principal Investigator |
MIZUTA Toshio Akita University, Mining College, Associate Professor, 鉱山学部, 助教授 (80094051)
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| Co-Investigator(Kenkyū-buntansha) |
ISHIYAMA Daizo Akita University, Mining College, Lecturer, 鉱山学部, 講師 (30193361)
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| Project Period (FY) |
1995 – 1996
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| Keywords | sulfide minerals / diffusion in sulfides / pyrite / sphalerite / ore textures / Zn-Fe-S system / hydrothermal synthesis / Auger spectrometer |
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| Research Abstract |
Ore-forming processes were examined from the experimental results of sulfide diffusion and distribution of trace elements between solution and sulfide minerals. Then, textures of ores from some seafloor hydrothermal deposits and Kuroko deposits are quantitatively analyzed from the viewpoint of crystal-size distribution theory.
1.Diffusion rates in sulfide minerals in Zn-Fe-S system and stability relationships are examined by annealing experiments using mainly Auger spectrometer. Obtained results of diffusion rates are relatively higher the activation energy is lower than previous interdiffusion studies by electron probe analyzes.
2.Distribution of trace elements such as cobalt and nickel between chloride solutions and pyrite were performed by hydrothermal synthesis method. Distribution coefficients were calculated from the data of Co^<2+>/Fe^<2+> ratios in solutions and pyrite from experiments at the temperatures of 200-300ﾟC.Distribution coefficients for recent seafloor hydrothermal ores and Kuroko-type ores with mineralized solutions are estimated from the data of the obtained distribution coefficients. Cobalt distribution in minerals are confirmed as an useful tool for the considerations of ore forming processes.
3.Using the apparatus purchased in this study, the size (axs, perimeters, directions of elongation, and so on) of chalcopyrite blebs are analyzed with the image processing methods. Such kinetic phenomena of 'chalcopyrite disease' were interpreted from the experimentally determined diffusion results. Diffusion time span and growth rates of chalcopyrite grains in sphalerite crystals are discussed in submitted paper to the International Journal.
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[Publications] Maglambayan,V.B.,Ishikawa,Y.,Mizuta,T.and Ishiyama,D.: "Ore textures and fluid inclusion studies of the Uwamuki No.4 Kuroko orebody,Akita Prefecture,Japan." Jour.Min.Coll.Akita Univ.,Ser.A,. 8. 1-13 (1997)
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[Publications] Fujita, T., Fujimoto, Y., Akibayashi, S., Kosukegawa, H.Yamamoto, Y., and Mizuta, T.: "Experimental studies on temperature dependence of resistivity of dried rocks." Jour.Geotherm.Res.Soc.Japan. vol.17., No.2. 111-121 (1995)
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[Publications] Hida, T., Ishiyama, D., Mizuta, T., and Ishikawa, Y.: "Geologic-characteristics and formation environments of the Yano-Shokozan pyrophyllite deposit, Hiroshima Prefecture, Japan. -Volcanic successions and hydrothermal alteration processes-" Jour.Clay Science Soc.Japan. Vol.36, No.2. 62-72 (1996)
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