慶南 咸安―郡北地域의 銅鑛化作用에 關한 硏究

Copper mineralization at Haman-Gunbuk mining district, Kyeongnam area

More than fifty copper veins are emplaced around late Cretaceous granitoid stock in Haman-Gunbuk district, southernmost part of Korea. These veins cut both late Cretaceous granitoids and hornfels of Jindong formation which is intruded by the granitoids. The paragenesis of veins is nearly the same, consisting of (1) an early vein stage in which most iron oxide minerals, tourmaline and other silitcate minerals were deposited, (2) a calcite and quartz with base-metal sulfide stage and (3) late veinlets of barren calcite stage. Fluid inclusion studies reveal highly systematic trends of salinity and temperature during mineralization. Ore fluids of early vein stage were complex NaCl-KCl rich brines. Salinities of polyphase inclusions in quartz and scapolite in thie stage reached up to 72 wt.% and gradually decreased to 10.5wt.% in closing stage. Homogenization temperatures of inclusions in the beginning of this stage were up to 490℃ and then declined steadly to 290℃ in the late stage. Salinities of fluid inclusions in quartz and calcite of base-metal sulfide stage were 37.4~5.7wt.% and homogenization temperatures range from 373℃ to 170℃. Intermittent boiling of early vein fluid is indicated by fluid inclusions in quartz. Potassic alteration of granodiorite adjacent to early vein seems to be related to early saline vein fluid. Fluid inclusion data of base-metal sulfide stage of this area reveal nearly the same range as those of Koseong copper mining district about 30km apart from this area.