Econ. Environ. Geol. 2002; 35(4): 299-316

Published online August 31, 2002

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Stable isotope, Fluid Inclusion and Mineralogical Studies of the Samkwang Gold-Silver Deposits, Republic of Korea

Bong Chul Yoo1*, Hyun Koo Lee1 and Seon Gyu Choi2

1Department of geology, Chungnam National University
2Department of earth and environmental sciences, Korea University

Correspondence to :

Bong Chul Yoo

s_chbong@cnu.ac.kr

Received: March 25, 2002; Accepted: August 13, 2002

Abstract

The Samkwang gold-silver deposits consist of gold-silver-bearing hydrothermal massive quartz veins which filled the fractures along fault shear (NE, NW) zones within Precambrian banded or granitic gneiss of Gyeonggi massif. Ore mineralization of this deposits occurred within a single stage of quartz vein which was formed by multiple episodes of fracturing and healing. Based on vein mineralogy and paragenesis, massive quartz veins are divided into two main paragenetic stages which are separated by a major faulting event. Main ore mineralization occurred at stage I. Wall-rock alteration from this deposits occur as mainly sericitization, chloritization, silicification and minor amounts of pyritization, carbonitization, propylitization and argillitization. Ore minerals are composed mainly of arsenopyrite (29.21~32.24 As atomic %), pyrite, sphalerite (6.45~13.82 FeS mole %), chalcopyrite, galena with minor amounts of pyrrhotite, marcasite, electrum (39.98~66.82 Au atomic %) and argentite. Systematic studies of fluid inclusions in early quartz veins and microcracks indicate two contrasting physical-chemical conditions : 1). temperature (215~345oC) and pressure (1296~2022 bar) event with H2O-CO2-CH4-NaCl fluids (0.8~6.3 wt. %) related to the early sulfide deposition, 2). temperature (203~441oC) and pressure (320 bar) event with H2O-NaCl ± CO2 fluids (5.7±8.8 wt. %) related to the late sulfide and electrum assemblage. The H2O-NaCl ± CO2 fluids represent fluids evolved through fluid unmixing of an H2O-CO2-CH4-NaCl fluids due to decreases in fluid pressure and influenced of deepcirculated meteoric waters possibly related to uplift and unloading of the mineralizing suites. Calculated sulfur isotope compositions (δ34Sfluid) of hydrothermal fluids (1.8~4.9‰) indicate that ore sulfur was derived from an igneous source. Measured and calculated oxygen and hydrogen isotope compositions (δ18OH2O, δD) of ore fluids (-5.9~10.9‰, -102~-87‰) indicate that mesothermal auriferous fluids at Samkwang gold-silver deposits were likely mixtures of H2O-rich, isotopically less evolved meteoric water and magmatic fluids.

Keywords Samkwang gold-silver deposits, Ore mineralization, Fluid inclusion, Stable isotope.

Article

Econ. Environ. Geol. 2002; 35(4): 299-316

Published online August 31, 2002

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Stable isotope, Fluid Inclusion and Mineralogical Studies of the Samkwang Gold-Silver Deposits, Republic of Korea

Bong Chul Yoo1*, Hyun Koo Lee1 and Seon Gyu Choi2

1Department of geology, Chungnam National University
2Department of earth and environmental sciences, Korea University

Correspondence to:

Bong Chul Yoo

s_chbong@cnu.ac.kr

Received: March 25, 2002; Accepted: August 13, 2002

Abstract

The Samkwang gold-silver deposits consist of gold-silver-bearing hydrothermal massive quartz veins which filled the fractures along fault shear (NE, NW) zones within Precambrian banded or granitic gneiss of Gyeonggi massif. Ore mineralization of this deposits occurred within a single stage of quartz vein which was formed by multiple episodes of fracturing and healing. Based on vein mineralogy and paragenesis, massive quartz veins are divided into two main paragenetic stages which are separated by a major faulting event. Main ore mineralization occurred at stage I. Wall-rock alteration from this deposits occur as mainly sericitization, chloritization, silicification and minor amounts of pyritization, carbonitization, propylitization and argillitization. Ore minerals are composed mainly of arsenopyrite (29.21~32.24 As atomic %), pyrite, sphalerite (6.45~13.82 FeS mole %), chalcopyrite, galena with minor amounts of pyrrhotite, marcasite, electrum (39.98~66.82 Au atomic %) and argentite. Systematic studies of fluid inclusions in early quartz veins and microcracks indicate two contrasting physical-chemical conditions : 1). temperature (215~345oC) and pressure (1296~2022 bar) event with H2O-CO2-CH4-NaCl fluids (0.8~6.3 wt. %) related to the early sulfide deposition, 2). temperature (203~441oC) and pressure (320 bar) event with H2O-NaCl ± CO2 fluids (5.7±8.8 wt. %) related to the late sulfide and electrum assemblage. The H2O-NaCl ± CO2 fluids represent fluids evolved through fluid unmixing of an H2O-CO2-CH4-NaCl fluids due to decreases in fluid pressure and influenced of deepcirculated meteoric waters possibly related to uplift and unloading of the mineralizing suites. Calculated sulfur isotope compositions (δ34Sfluid) of hydrothermal fluids (1.8~4.9‰) indicate that ore sulfur was derived from an igneous source. Measured and calculated oxygen and hydrogen isotope compositions (δ18OH2O, δD) of ore fluids (-5.9~10.9‰, -102~-87‰) indicate that mesothermal auriferous fluids at Samkwang gold-silver deposits were likely mixtures of H2O-rich, isotopically less evolved meteoric water and magmatic fluids.

Keywords Samkwang gold-silver deposits, Ore mineralization, Fluid inclusion, Stable isotope.

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

    Stats or Metrics

    Share this article on

    • kakao talk
    • line

    Related articles in KSEEG

    Economic and Environmental Geology

    pISSN 1225-7281
    eISSN 2288-7962
    qr-code Download