Econ. Environ. Geol. 2013; 46(2): 153-163

Published online April 30, 2013

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Genesis of the Ogcheon Gold-silver Deposit in Republic of Korea:Ore Minerals, Fluid Inclusion and Stable Isotope Studies

Bong Chul Yoo*

Mineral Resources Research Department, Korea Institute of Geoscience and Mineral Resources, Daejeon, 305-350, Korea

Correspondence to :

Bong Chul Yoo

chbong@kigam.re.kr

Received: March 2, 2013; Accepted: April 6, 2013

Abstract

The Ogcheon Au-Ag deposit consists of two quartz veins that fill the NE or NW-trending fissures in the metasedimentary rocks of unknown age. The quartz veins occur mainly in the massive type with partially breccia and cavity. They can be found along the strike for about minimum 50 m and varied in thickness from 0.1 to 0.3 m. The mineralogy of quartz veins from the Ogcheon deposit is mainly composed of hydrothermal alteration minerals such as pyrite, quartz, sericite, chlorite, clay minerals and sulfides including pyrite, pyrrhotite, arsenopyrite, sphalerite, chalcopyrite and galena. Fluid inclusion data from quartz indicate that homogenization temperatures and salinity
of mineralization range from 184 to 362oC and from 0.0 to 6.6 wt.% eq. NaCl, respectively. These suggest that ore forming fluids were progressively cooled and diluted from mixing with meteoric water. Sulfur(δ34S: 0.4~8.4‰) isotope composition indicates that ore sulfur was derived from mainly magmatic source although there is a partial derivation from the host rocks. The calculated oxygen(δ18O: 4.9 ~12.1‰) and hydrogen(δD: -92~-74‰) isotope compositions suggest that magmatic and meteoric ore fluids were equally important for the formation of the Ogcheon deposit and then overlapped to some degree with another type of meteoric water during mineralization.

Keywords Ogcheon deposit, quartz vein, mineralization, fluid inclusion, stable isotope

Article

Econ. Environ. Geol. 2013; 46(2): 153-163

Published online April 30, 2013

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Genesis of the Ogcheon Gold-silver Deposit in Republic of Korea:Ore Minerals, Fluid Inclusion and Stable Isotope Studies

Bong Chul Yoo*

Mineral Resources Research Department, Korea Institute of Geoscience and Mineral Resources, Daejeon, 305-350, Korea

Correspondence to:

Bong Chul Yoo

chbong@kigam.re.kr

Received: March 2, 2013; Accepted: April 6, 2013

Abstract

The Ogcheon Au-Ag deposit consists of two quartz veins that fill the NE or NW-trending fissures in the metasedimentary rocks of unknown age. The quartz veins occur mainly in the massive type with partially breccia and cavity. They can be found along the strike for about minimum 50 m and varied in thickness from 0.1 to 0.3 m. The mineralogy of quartz veins from the Ogcheon deposit is mainly composed of hydrothermal alteration minerals such as pyrite, quartz, sericite, chlorite, clay minerals and sulfides including pyrite, pyrrhotite, arsenopyrite, sphalerite, chalcopyrite and galena. Fluid inclusion data from quartz indicate that homogenization temperatures and salinity
of mineralization range from 184 to 362oC and from 0.0 to 6.6 wt.% eq. NaCl, respectively. These suggest that ore forming fluids were progressively cooled and diluted from mixing with meteoric water. Sulfur(δ34S: 0.4~8.4‰) isotope composition indicates that ore sulfur was derived from mainly magmatic source although there is a partial derivation from the host rocks. The calculated oxygen(δ18O: 4.9 ~12.1‰) and hydrogen(δD: -92~-74‰) isotope compositions suggest that magmatic and meteoric ore fluids were equally important for the formation of the Ogcheon deposit and then overlapped to some degree with another type of meteoric water during mineralization.

Keywords Ogcheon deposit, quartz vein, mineralization, fluid inclusion, stable isotope

    KSEEG
    Apr 30, 2024 Vol.57 No.2, pp. 107~280

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