Hydrothermal Gold Mineralization of the Sambo Deposit in the Muan Area, Korea

The Sambo gold deposit located nearby the Cretaceous Hampyeong basin is composed of gold quartz fine vein(the Jija vein) within Cretaceous rhyolite showing N10 similar to 20W trends as well as N5 similar to 10E trending quartz veins(the Pungja, Gwangsan and Pungjaji veins) in Precambrian gneiss. The gold vein typically displays the intermittent and irregular fine veins within rhyolite. Electrum is disseminated in wallrock along the fine cracks as well as coexists with hematite replacing pyrite. Ore-forming fluids from the mineralized vein(H2O/-NaCl system, Th; 340 similar to 200 degrees C, Salinity <2.7 eq. wt.% NaCl) and NE-trending veins(H2O-NaCl/-CO2 system, Th; 400 similar to 190 degrees C, salinity <7.9 eq. wt.% NaCl) are featured by dissimilar physicochemical conditions but their fluid evolution trends(boiling and mixing) are similar with each other. Gold veins of the Sambo deposit filled along NNW-trending tension crack are related to pull-apart basin evolution. Selective gold mineralization of the deposit reflect to dissimilarity between two ore-forming fluid sources. Consequently, gold veining of the Sambo deposit formed at shallow-crustal level and could be categorized into epithermal-type gold deposit related to tensional fractures filling triggered by Cretaceous geodynamics.