• Economic and Environmental Geology
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• v.54 no.6
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• pp.753-765
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• 2021

The Dongwon Au-Ag deposit is located within the Paleozoic Taebaeksan province, Okcheon belt. Mineral paragenesis can be divided into two stages (stage I, ore-bearing quartz veins; stage II, barren carbonate veins) by major tectonic fracturing. Stage I, at which the precipitation of major ore minerals occurred, is further divided into three substages(early, middle and late) with paragenetic time based on minor fractures and discernible mineral assemblages: early, marked by deposition of pyrite with minor magnetite, pyrrhotite and arsenopyrite; middle, characterized by introduction of electrum and base-metal sulfides with minor sulfosalts; late, marked by argentite, Cu-As (and/or Sb) and Ag-Sb sulfosalts with base-metal sulfides. Fluid inclusion data show that stage I ore mineralization was deposited between initial high temperatures (≥430℃) and later lower temperatures (≤230℃) from fluids with salinities between 6.0 to 0.4 wt. percent equiv. NaCl. The relationship of salinity and homogenization temperature suggest that ore mineralization at Dongwon was deposited mainly due to fluid boiling, cooling and dilution via influx of cooler, more dilute meteoric waters. Changes in stage I vein mineralogy reflect decreasing temperature and fugacity of sulfur by evolution of the Dongwon hydrothermal system with increasing paragenetic time. The Dongwon deposit may represents a Korean-type and/or Au-Ag type mesothermal/epithermal gold-silver deposit.