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Skarn gold mineralization at the geodo mine, south Korea / Eui-Jun Kim in Economic geology, Vol. 107 N° 3 (Mai 2012) 

Public ISBD [article]  in Economic geology > Vol. 107 N° 3 (Mai 2012) . - pp. 537-551 Titre : Skarn gold mineralization at the geodo mine, south Korea Type de document : texte imprimé Auteurs : Eui-Jun Kim, Auteur ; Maeng-Eon Park, Auteur ; Noel C. White, Auteur Année de publication : 2012 Article en page(s) : pp. 537-551 Note générale : Economic geology Langues : Anglais (eng) Mots-clés : Bi-Te-bearing  skarn  deposit  Gold  deposit  Geodo  skarn  Korea Index. décimale : 553 Géologie économique. Minérographie. Minéraux. Formation et gisements de minerais Résumé : The Geodo Bi-Te–bearing skarn deposit is located in the Taebaeksan mining district, South Korea. Both endoskarn and exoskarn are associated with the Cretaceous Eopyeong granitoids, which consist of magnetite-bearing oxidized (Fe2O3/FeO > 0.4) quartz monzodiorite to monzodiorite. Gold in the Geodo Mine occurs in a retrograde alteration stage within a garnet-rich proximal zone. Skarn minerals associated with gold ore include Fe-rich garnet (Ad57–95Gr1–41) and a wide range of clinopyroxene (Hd20–100Di0–79) compositions, broadly similar to those of typical gold-bearing skarn deposits. The paragenetic stages of the Bi- and Te-bearing skarn in the Geodo Mine consist of early calc-silicate alteration followed by three mineralization stages: Fe oxide, Cu rich, and Au rich. The Fe oxide and Cu-rich stages were deposited at higher temperatures than the Au-rich stage, based on mineral assemblage stabilities. Gold in Au-rich ores from the Geodo Mine occurs as native gold, ranging from 5 to 400 μm in diameter, and is closely related to the Bi- and Te-bearing minerals bismuthinite and tetradymite, which at Geodo tend to be strongly enriched in Bi and depleted in S compared to ideal compositions. This association of gold with bismuthinite and tetradymite suggests that gold was deposited at relatively low temperatures, consistent with fluid inclusion studies on calcite that indicate that the gold was deposited from fluids ranging from 181° to 281°C and 8.0 to 10.9 wt % NaCl equiv, and with chlorite geothermometry indicating a range of 198° to 211°C. The presence of significant amounts of Bi- and Te-bearing minerals associated with Au suggests that liquid bismuth may have acted as a collector, increasing the concentration of gold. DEWEY : 553 ISSN : 0361-0128 En ligne : http://econgeol.geoscienceworld.org/content/107/3/537.short [article] Skarn gold mineralization at the geodo mine, south Korea [texte imprimé] / Eui-Jun Kim, Auteur ; Maeng-Eon Park, Auteur ; Noel C. White, Auteur . - 2012 . - pp. 537-551. Economic geology Langues : Anglais (eng) in Economic geology > Vol. 107 N° 3 (Mai 2012) . - pp. 537-551 Mots-clés : Bi-Te-bearing  skarn  deposit  Gold  deposit  Geodo  skarn  Korea Index. décimale : 553 Géologie économique. Minérographie. Minéraux. Formation et gisements de minerais Résumé : The Geodo Bi-Te–bearing skarn deposit is located in the Taebaeksan mining district, South Korea. Both endoskarn and exoskarn are associated with the Cretaceous Eopyeong granitoids, which consist of magnetite-bearing oxidized (Fe2O3/FeO > 0.4) quartz monzodiorite to monzodiorite. Gold in the Geodo Mine occurs in a retrograde alteration stage within a garnet-rich proximal zone. Skarn minerals associated with gold ore include Fe-rich garnet (Ad57–95Gr1–41) and a wide range of clinopyroxene (Hd20–100Di0–79) compositions, broadly similar to those of typical gold-bearing skarn deposits. The paragenetic stages of the Bi- and Te-bearing skarn in the Geodo Mine consist of early calc-silicate alteration followed by three mineralization stages: Fe oxide, Cu rich, and Au rich. The Fe oxide and Cu-rich stages were deposited at higher temperatures than the Au-rich stage, based on mineral assemblage stabilities. Gold in Au-rich ores from the Geodo Mine occurs as native gold, ranging from 5 to 400 μm in diameter, and is closely related to the Bi- and Te-bearing minerals bismuthinite and tetradymite, which at Geodo tend to be strongly enriched in Bi and depleted in S compared to ideal compositions. This association of gold with bismuthinite and tetradymite suggests that gold was deposited at relatively low temperatures, consistent with fluid inclusion studies on calcite that indicate that the gold was deposited from fluids ranging from 181° to 281°C and 8.0 to 10.9 wt % NaCl equiv, and with chlorite geothermometry indicating a range of 198° to 211°C. The presence of significant amounts of Bi- and Te-bearing minerals associated with Au suggests that liquid bismuth may have acted as a collector, increasing the concentration of gold. DEWEY : 553 ISSN : 0361-0128 En ligne : http://econgeol.geoscienceworld.org/content/107/3/537.short