A Rb-Sr GEOCHRONOLOGICAL STUDY OF PORPHYRIES IN THE KAMIOKA MINING DISTRICT, CENTRAL JAPAN

Seki, Tatsuya

doi:10.2465/ganko1941.67.410

Cited by 5 publications

(4 citation statements)

References 10 publications

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“…Granite porphyry and quartz porphyry in the Kamioka mining area represent some hypabyssal components of that activity. Seki (1972) reported an Rb-Sr age of 87 Ma for these porphyries.…”

Section: Me Tabasitementioning

confidence: 99%

Oxygen isotope study of the Kamioka Zn-Pb skarn deposits, Central Japan

Shimazaki

Kusakabe

1990

Mineral. Deposita

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The Kamioka Zn-Pb deposits consist of clinopyroxene-rich skarns replacing limestone lenses in Hida gneissose rocks. Paleozoic metabasite, early Jurassic Funatsu granitic rocks and late Cretaceous porphyritic dikes and stocks, are the known igneous rocks in the mining area. Oxygen isotopic compositions of eight separates each of clinopyroxene and quartz from the deposits (Table 1), and some minerals and rocks from the major rock units around the deposits (Table 2), have been analyzed. The estimated oxygen isotopic ratios of the fluids responsible for the formation of the deposits, range as low as -4%0 to + 3%0 (SMOW). These values are considerably lower than expected from magmatic waters, and demonstrate that none of the igneous rocks in the area could be a direct source of the skarn-and ore-forming fluids. The data instead show that the deposits are formed by a huge convective circulation of solutions of meteoric water origin, promoted by a hidden batholithic intrusion at the time of the late Cretaceous.

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“…Granite porphyry and quartz porphyry in the Kamioka mining area represent some hypabyssal components of that activity. Seki (1972) reported an Rb-Sr age of 87 Ma for these porphyries.…”

Section: Me Tabasitementioning

confidence: 99%

Oxygen isotope study of the Kamioka Zn-Pb skarn deposits, Central Japan

Shimazaki

Kusakabe

1990

Mineral. Deposita

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“…K-Ar, Rb-Sr, and U-Pb age data vary from 210 to 140 Ma with a peak at about 180 Ma (Shibata and Nozawa, 1984 ;;;;;; ;;;;;; ;;;;;; ;;;;;; ;;;; ;;;; ;;;; ;;;; ;;;; ;;;; ;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;;;;;; ;;;; ;;;; ;;;; ;;;; ;;;; ;;;;; ;;;;; ;;;;; ;;;;;; ;;;;;; ;;;;;; ;;;;;; reported to be 89 ±11 Ma (Seki, 1972). There have been disputes as to which igneous activity was related to the mineralization.…”

Section: Geological Setting and Ore Depositsunclassified

“…reported to be 89 ±11 Ma (Seki, 1972). There have been disputes as to which igneous activity was related to the mineralization.…”

Section: Geological Setting and Ore Depositsmentioning

confidence: 99%

Genesis of the Kamioka Skarn Deposits: An Important Role of Clinopyroxene Skarn and Graphite‐bearing Limestone in Precipitating Sulfide Ore

Kato

1999

Resource Geology

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A genetical relationship between skarn formation and mineralization is investigated for the Kamioka skarn deposits which are the largest Zn-Pb producer in Japan. In the Mozumi deposit, one of main deposits in the Kamioka mining area as well as Tochibora and Maruyama, clinopyroxene skarn was generally subjected to later replacement by garnet or magnetitecalcite-quartz during the Zn-Pb mineralization. The replacement of hedenbergitic clinopyroxene by andraditic garnet resulted in the formation of diopsidic clinopyroxene relicts. With the progress of replacement, the S/So value (So: an estimated area occupied by an original clinopyroxene grain in a thin section, S: a total area of relict clinopyroxene fragments) which is an index of the degree of replacement decreases from 0.7 to 0.1, and the hedenbergite mole percent of relict clinopyroxene decreases drastically from about 65 to less than 40. A close association of andraditic garnet and sphalerite suggests that hedenbergitic clinopyroxene skarn played an important role to reduce the relatively oxic ore-forming fluid enriched in Zn 2+ and SO4 2-and to precipitate sphalerite from the fluid. Ferrous iron in the hedenbergitic clinopyroxene skarn was oxidized to form andraditic garnet. Besides this garnet formation, the mineral assemblage of magnetite-calcite-quartz replaced the clinopyroxene skarn at the time of mineralization. In both cases, the reduction of relatively oxic ore-forming fluid by hedenbergitic clinopyroxene skarn at the later stage brought about the precipitation of sulfide minerals.In contrast, these types of later replacement are not found in the Tochibora deposit. Instead, graphite-bearing crystalline limestone and relatively fresh clinopyroxene skarn are common. Mineralized clinopyroxene skarn has high graphite carbon contents relative to barren one, suggesting that the amount of graphite in the skarn was an important controlling factor for mineralization. It is very likely that the graphite played a role of reducing agent during the mineralization in the Tochibora deposit.

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“…Because the Kamioka mine has been worked for long time, many papers have been so far published on geology (e.g., Akiyama, 1980;Kano and Hori, 1982;Kano et al, 1989;Kano, 1992), on geochemistry (e.g., Seki 1972Seki , 1991Kiyosu and Nakai, 1977;Sato et al, 1978;Wada, 1978;Shimazaki and Kusakabe, 1990a,b) and on metallogeny (e.g., Narita, 1959;Fonteilles, 1962;Okuno, 1964;Tsukagoshi et al, 1974;Akiyama, 1981;Nitta and Akiyama, 1981;Kato, 1991;Mariko et al, 1996). Compared with these vast amount of papers, papers on fluid inclusion studies are limited.…”

Section: Introductionmentioning

confidence: 99%

Fluid Inclusion Study of Skarns in the Maruyama Deposit, the Kamioka Mine, Central Japan

et al. 1999

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Fluid inclusions in skarn minerals in the Maruyama deposit, the Kamioka mine, central Japan were studied. Homogenization temperatures (Th) of fluid inclusions in 48 skarn minerals (hedenbergite, andradite, epidote and quartz) were measured, and gas composition of fluid inclusions in 12 skarn minerals was measured with a quadrupole mass spectrometer. The maximum Th value of primary inclusions in hedenbergite is 380°C with peaks around 360°C. Primary inclusions in hedenbergite near contact between skarn and limestone have slightly lower Th values and their distribution has a tendency of long trail skirt toward low temperature, which indicates ceasing of skarnization coincides with temperature decrease. Fluid inclusions in andradite and quartz in the hedenbergite skarn have lower Th values, in this order, than those in hedenbergite. CH4-detected fluid inclusions are localized around the Maruyama fault. Gas composition of the fluid inclusions indicates that fluid trapped in the hedenbergite has CO2 content less than 1 mole % and is not in equilibrium with graphite.

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A Rb-Sr GEOCHRONOLOGICAL STUDY OF PORPHYRIES IN THE KAMIOKA MINING DISTRICT, CENTRAL JAPAN

Cited by 5 publications

References 10 publications

Oxygen isotope study of the Kamioka Zn-Pb skarn deposits, Central Japan

Oxygen isotope study of the Kamioka Zn-Pb skarn deposits, Central Japan

Genesis of the Kamioka Skarn Deposits: An Important Role of Clinopyroxene Skarn and Graphite‐bearing Limestone in Precipitating Sulfide Ore

Fluid Inclusion Study of Skarns in the Maruyama Deposit, the Kamioka Mine, Central Japan

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