덕흔ㆍ法田鑛山의 金-銀鑛化作用

The gold-silver mineralization of the Deogheun and Beopjeon mines

Gold-silver deposits of Deogheun and Beopjeon mines are composed of veins emplaced in Jurassic granite batholith. Based on ore structure and ore mineralogy, four distinct stages of mineral deposition are recognized in these ore deposits. Gold and silver minerals in Deogheun and Beopjeon-A ore deposits are precipitated in stage Ⅲ and stage Ⅱ, respectively. Mineral constituents of ores from these deposits are pyrite, sphalerite, arsenopyrite, pyrrhotite, chalcopyrite, galena, tetrahedrite, electrum, quartz and rhodochrosite. Cubanite, argentite and pyrargyrite occur only in Deogheun ore deposits. Ag content of electrum range from 42 to 66 atomic % in both ore deposits. Filling temperature of fluid inclusion from both ore deposits are as follows ; stage Ⅰ, 211-289℃ ; stage Ⅱ, 205-290℃ ; stage Ⅲ, 190-260℃ ; stage Ⅳ, 136-222℃ in Deogheun ore deposits. In Beopjeon-A ore deposits, stage Ⅰ, 255-305℃ ; stage Ⅱ, 135-222℃ ; stage Ⅲ, 148-256℃ ; stage Ⅳ, 103-134℃. Salinities of fluid inclusions range from 1.6-8.5 wt.% equivalent NaCl in both ore deposits. Sulfur fugacities through stage Ⅱ and Ⅲ in Deogheun ore deposits inferred from data of mineral assemblage and fluid inclusion range from 10-11.0-10-16.1 bars. Fluid pressure estimated from fluid inclusions which reveal boiling evidence range from 30-190 bars during mineralization in Deogheun ore deposits.