Original Article

Econ. Environ. Geol. 2017; 50(5): 325-340

Published online October 31, 2017

https://doi.org/10.9719/EEG.2017.50.5.325

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Mineralogy and Genetic Environments of the Seongdo Pb-Zn deposit, Goesan

Seongyeol Ahn and Dongbok Shin*

Department of Geoenvironmental Sciences, Kongju National University

Correspondence to : shin@kongju.ac.kr

Received: July 27, 2017; Revised: August 25, 2017; Accepted: September 4, 2017

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

The Seongdo Pb-Zn deposit, located in the northwestern part of the Ogcheon Metamorphic Belt, consists of skarn ore replacing limestone within the Hwajeonri Formation of Ogcheon Group and hydrothermal vein ore filling the fracture of host rock. Skarn minerals comprise mostly hedenbergitic pyroxene, garnet displaying oscillatory zonal texture composed of grossular and andradite, and a small amount of wollastonite, tremolite, and epidote, indicating reducing condition of formation. Ore minerals of skarn ore include sphalerite and galena with a small amount of pyrite, pyrrhotite, and chalcopyrite. In hydrothermal vein ore, arsenopyrite, sphalerite, chalcopyrite, and pyrite occur with a small amount of galena, native Bi, and stannite. Chemical compositions of sphalerite vary from 17.4 mole% FeS in average for dark grey sphalerite, 3.6 mole% for reddish brown sphalerite in skarn ore, and to 10.3 mole% FeS in hydrothermal vein ore. In comparison with representative metallic deposits in South Korea on the FeS-MnSCdS diagram, skarn and hydrothermal vein ore plot close to the field of Pb-Zn deposits and Au-Ag deposits, respectively. Arsenic contents of arsenopyrite in hydrothermal vein ore decrease from 31.93~33.00 at.% in early stage to 29.58~30.21 at.% in middle stage, and their corresponding mineralizing temperature and sulfur fugacity are 441~490°C, 10-6~10-4.5 atm. and 330~364°C, 〈10-8 atm. respectively. Phase equilibrium temperatures calculated from Fe and Zn contents for coexisting sphalerite and stannite in hydrothermal vein are 236~254°C. Sulfur isotope compositions are 5.4~7.2‰ for skarn ore and 5.4~8.4‰ for hydrothermal vein ore, being similar or slightly higher to magmatic sulfur, suggesting that ore sulfur was mostly of magmatic origin with partial derivation from host rocks. However, much higher sulfur isotope equilibrium temperatures of 549°C and 487°C, respectively for skarn ore and hydrothermal ore, than those estimated from phase equilibria imply that isotopic equilibrium has not been fully established.

Keywords Seongdo deposit, skarn, hydrothermal deposit, sphalerite, sulfur isotope

괴산 성도 연-아연 광상의 산출광물과 생성환경

안성열 ·신동복*

공주대학교 지질환경과학과

요 약

Article

Original Article

Econ. Environ. Geol. 2017; 50(5): 325-340

Published online October 31, 2017 https://doi.org/10.9719/EEG.2017.50.5.325

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Mineralogy and Genetic Environments of the Seongdo Pb-Zn deposit, Goesan

Seongyeol Ahn and Dongbok Shin*

Department of Geoenvironmental Sciences, Kongju National University

Correspondence to:shin@kongju.ac.kr

Received: July 27, 2017; Revised: August 25, 2017; Accepted: September 4, 2017

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

The Seongdo Pb-Zn deposit, located in the northwestern part of the Ogcheon Metamorphic Belt, consists of skarn ore replacing limestone within the Hwajeonri Formation of Ogcheon Group and hydrothermal vein ore filling the fracture of host rock. Skarn minerals comprise mostly hedenbergitic pyroxene, garnet displaying oscillatory zonal texture composed of grossular and andradite, and a small amount of wollastonite, tremolite, and epidote, indicating reducing condition of formation. Ore minerals of skarn ore include sphalerite and galena with a small amount of pyrite, pyrrhotite, and chalcopyrite. In hydrothermal vein ore, arsenopyrite, sphalerite, chalcopyrite, and pyrite occur with a small amount of galena, native Bi, and stannite. Chemical compositions of sphalerite vary from 17.4 mole% FeS in average for dark grey sphalerite, 3.6 mole% for reddish brown sphalerite in skarn ore, and to 10.3 mole% FeS in hydrothermal vein ore. In comparison with representative metallic deposits in South Korea on the FeS-MnSCdS diagram, skarn and hydrothermal vein ore plot close to the field of Pb-Zn deposits and Au-Ag deposits, respectively. Arsenic contents of arsenopyrite in hydrothermal vein ore decrease from 31.93~33.00 at.% in early stage to 29.58~30.21 at.% in middle stage, and their corresponding mineralizing temperature and sulfur fugacity are 441~490°C, 10-6~10-4.5 atm. and 330~364°C, 〈10-8 atm. respectively. Phase equilibrium temperatures calculated from Fe and Zn contents for coexisting sphalerite and stannite in hydrothermal vein are 236~254°C. Sulfur isotope compositions are 5.4~7.2‰ for skarn ore and 5.4~8.4‰ for hydrothermal vein ore, being similar or slightly higher to magmatic sulfur, suggesting that ore sulfur was mostly of magmatic origin with partial derivation from host rocks. However, much higher sulfur isotope equilibrium temperatures of 549°C and 487°C, respectively for skarn ore and hydrothermal ore, than those estimated from phase equilibria imply that isotopic equilibrium has not been fully established.

Keywords Seongdo deposit, skarn, hydrothermal deposit, sphalerite, sulfur isotope

괴산 성도 연-아연 광상의 산출광물과 생성환경

안성열 ·신동복*

공주대학교 지질환경과학과

Received: July 27, 2017; Revised: August 25, 2017; Accepted: September 4, 2017

요 약

    KSEEG
    Jun 30, 2024 Vol.57 No.3, pp. 281~352

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