Compositional variation of arsenopyrite and fluid evolution at the Ulsan deposit, southeastern Korea: A low-sulfidation porphyry system

Seon-Gyu Choi, S. J. Youm

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23 Citations (Scopus)

Abstract

The Ulsan Fe-W mine is located within the Cretaceous Gyeongsang volcano-sedimentary basin at the southeastern edge of the Korean Peninsula. Distinct hydrothermal events resulted in calcic skarn and vein deposits in recrystallized limestone near a Tertiary epizonal granite stock. The deposits of the Ulsan mine present a unique opportunity to document geochemically the complex evolution of a skarn-vein system that is related genetically to a low-sulfidation system. Isochemical contact metamorphism of an early skarn stage (stage I) is displayed by the presence of anhydrous Ca-Al-Mg skarn minerals at the contact between granite and recrystallized limestone. Following magnetite deposition in the main prograde skarn (stage II), the first deposition of arsenopyrite occurs intergrown with rammelsbergite - niccolite - gersdorffite - lollingite - native bismuth - bismuthinite - hexagonal pyrrhotite. These common sulfide assemblages are characterized by an overall low-sulfidation state during the main skarn stage. Retrograde skarn (stage III) is characterized by minor impregnations of scheelite in calcite and quartz, with actinolite and chlorite. During the latest part of stage III, Cu-Zn and polymetallic sulfide mineralization was introduced. The latest episode in the hydrothermal system (stage IV) is characterized by Zn-Pb-Ag mineralization in siderite-quartz veins. Decreasing As contents in arsenopyrite from stages II to IV indicate a decrease in temperature or sulfur fugacity (or both) with time. The various skarn-forming events and ore minerals from various stages are interpreted to have resulted from an evolutionary trend from hypersaline magmatic fluids during prograde skarn formation associated with Fe-As(-Ni) mineralization to low-salinity and low-temperature fluids during the retrograde skarn formation, associated with W-Cu-Zn mineralization. As the influence of magma-derived fluids waned, surficial fluids descended to deeper levels along fractures, resulting in siderite-quartz deposition associated with Zn-Pb-Ag mineralization. These results demonstrate that the Ulsan deposit is likely a skarn deposit that is genetically related to a low-sulfidation porphyry system.

Original languageEnglish
Pages (from-to)567-583
Number of pages17
JournalCanadian Mineralogist
Volume38
Issue number3
Publication statusPublished - 2000 Jan 1

Fingerprint

arsenopyrite
skarn
porphyry
Quartz
Calcium Carbonate
Deposits
Fluids
fluid
Sulfides
Minerals
Ferrosoferric Oxide
mineralization
Bismuth
Volcanoes
Sulfur
Impregnation
Ores
siderite
Temperature
granite

Keywords

  • Arsenopyrite
  • Fe-W skarn
  • Fluid evolution
  • Fluid inclusions
  • Geothermometry
  • Low sulfidation
  • Polymetallic
  • Southeastern Korea
  • Ulsan

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

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title = "Compositional variation of arsenopyrite and fluid evolution at the Ulsan deposit, southeastern Korea: A low-sulfidation porphyry system",
abstract = "The Ulsan Fe-W mine is located within the Cretaceous Gyeongsang volcano-sedimentary basin at the southeastern edge of the Korean Peninsula. Distinct hydrothermal events resulted in calcic skarn and vein deposits in recrystallized limestone near a Tertiary epizonal granite stock. The deposits of the Ulsan mine present a unique opportunity to document geochemically the complex evolution of a skarn-vein system that is related genetically to a low-sulfidation system. Isochemical contact metamorphism of an early skarn stage (stage I) is displayed by the presence of anhydrous Ca-Al-Mg skarn minerals at the contact between granite and recrystallized limestone. Following magnetite deposition in the main prograde skarn (stage II), the first deposition of arsenopyrite occurs intergrown with rammelsbergite - niccolite - gersdorffite - lollingite - native bismuth - bismuthinite - hexagonal pyrrhotite. These common sulfide assemblages are characterized by an overall low-sulfidation state during the main skarn stage. Retrograde skarn (stage III) is characterized by minor impregnations of scheelite in calcite and quartz, with actinolite and chlorite. During the latest part of stage III, Cu-Zn and polymetallic sulfide mineralization was introduced. The latest episode in the hydrothermal system (stage IV) is characterized by Zn-Pb-Ag mineralization in siderite-quartz veins. Decreasing As contents in arsenopyrite from stages II to IV indicate a decrease in temperature or sulfur fugacity (or both) with time. The various skarn-forming events and ore minerals from various stages are interpreted to have resulted from an evolutionary trend from hypersaline magmatic fluids during prograde skarn formation associated with Fe-As(-Ni) mineralization to low-salinity and low-temperature fluids during the retrograde skarn formation, associated with W-Cu-Zn mineralization. As the influence of magma-derived fluids waned, surficial fluids descended to deeper levels along fractures, resulting in siderite-quartz deposition associated with Zn-Pb-Ag mineralization. These results demonstrate that the Ulsan deposit is likely a skarn deposit that is genetically related to a low-sulfidation porphyry system.",
keywords = "Arsenopyrite, Fe-W skarn, Fluid evolution, Fluid inclusions, Geothermometry, Low sulfidation, Polymetallic, Southeastern Korea, Ulsan",
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TY - JOUR

T1 - Compositional variation of arsenopyrite and fluid evolution at the Ulsan deposit, southeastern Korea

T2 - A low-sulfidation porphyry system

AU - Choi, Seon-Gyu

AU - Youm, S. J.

PY - 2000/1/1

Y1 - 2000/1/1

N2 - The Ulsan Fe-W mine is located within the Cretaceous Gyeongsang volcano-sedimentary basin at the southeastern edge of the Korean Peninsula. Distinct hydrothermal events resulted in calcic skarn and vein deposits in recrystallized limestone near a Tertiary epizonal granite stock. The deposits of the Ulsan mine present a unique opportunity to document geochemically the complex evolution of a skarn-vein system that is related genetically to a low-sulfidation system. Isochemical contact metamorphism of an early skarn stage (stage I) is displayed by the presence of anhydrous Ca-Al-Mg skarn minerals at the contact between granite and recrystallized limestone. Following magnetite deposition in the main prograde skarn (stage II), the first deposition of arsenopyrite occurs intergrown with rammelsbergite - niccolite - gersdorffite - lollingite - native bismuth - bismuthinite - hexagonal pyrrhotite. These common sulfide assemblages are characterized by an overall low-sulfidation state during the main skarn stage. Retrograde skarn (stage III) is characterized by minor impregnations of scheelite in calcite and quartz, with actinolite and chlorite. During the latest part of stage III, Cu-Zn and polymetallic sulfide mineralization was introduced. The latest episode in the hydrothermal system (stage IV) is characterized by Zn-Pb-Ag mineralization in siderite-quartz veins. Decreasing As contents in arsenopyrite from stages II to IV indicate a decrease in temperature or sulfur fugacity (or both) with time. The various skarn-forming events and ore minerals from various stages are interpreted to have resulted from an evolutionary trend from hypersaline magmatic fluids during prograde skarn formation associated with Fe-As(-Ni) mineralization to low-salinity and low-temperature fluids during the retrograde skarn formation, associated with W-Cu-Zn mineralization. As the influence of magma-derived fluids waned, surficial fluids descended to deeper levels along fractures, resulting in siderite-quartz deposition associated with Zn-Pb-Ag mineralization. These results demonstrate that the Ulsan deposit is likely a skarn deposit that is genetically related to a low-sulfidation porphyry system.

AB - The Ulsan Fe-W mine is located within the Cretaceous Gyeongsang volcano-sedimentary basin at the southeastern edge of the Korean Peninsula. Distinct hydrothermal events resulted in calcic skarn and vein deposits in recrystallized limestone near a Tertiary epizonal granite stock. The deposits of the Ulsan mine present a unique opportunity to document geochemically the complex evolution of a skarn-vein system that is related genetically to a low-sulfidation system. Isochemical contact metamorphism of an early skarn stage (stage I) is displayed by the presence of anhydrous Ca-Al-Mg skarn minerals at the contact between granite and recrystallized limestone. Following magnetite deposition in the main prograde skarn (stage II), the first deposition of arsenopyrite occurs intergrown with rammelsbergite - niccolite - gersdorffite - lollingite - native bismuth - bismuthinite - hexagonal pyrrhotite. These common sulfide assemblages are characterized by an overall low-sulfidation state during the main skarn stage. Retrograde skarn (stage III) is characterized by minor impregnations of scheelite in calcite and quartz, with actinolite and chlorite. During the latest part of stage III, Cu-Zn and polymetallic sulfide mineralization was introduced. The latest episode in the hydrothermal system (stage IV) is characterized by Zn-Pb-Ag mineralization in siderite-quartz veins. Decreasing As contents in arsenopyrite from stages II to IV indicate a decrease in temperature or sulfur fugacity (or both) with time. The various skarn-forming events and ore minerals from various stages are interpreted to have resulted from an evolutionary trend from hypersaline magmatic fluids during prograde skarn formation associated with Fe-As(-Ni) mineralization to low-salinity and low-temperature fluids during the retrograde skarn formation, associated with W-Cu-Zn mineralization. As the influence of magma-derived fluids waned, surficial fluids descended to deeper levels along fractures, resulting in siderite-quartz deposition associated with Zn-Pb-Ag mineralization. These results demonstrate that the Ulsan deposit is likely a skarn deposit that is genetically related to a low-sulfidation porphyry system.

KW - Arsenopyrite

KW - Fe-W skarn

KW - Fluid evolution

KW - Fluid inclusions

KW - Geothermometry

KW - Low sulfidation

KW - Polymetallic

KW - Southeastern Korea

KW - Ulsan

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M3 - Article

AN - SCOPUS:0033829189

VL - 38

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JO - Canadian Mineralogist

JF - Canadian Mineralogist

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