PRELIMINARY STUDY ON MANTO-TYPE POLYMETALLIC MINERALIZATION IN TAEBAEKSAN BASIN, SOUTH KOREA

Manto-type polymetallic mineralization is developed in Sedimentary rocks of Chosun Supergroup within Taebaeksan basin along the fissure developed by fault and fold. This mineralization is distinguished to two types, as relatively lower hydrothermal vein type and disseminated replacement type. Mineralization type is divided into Cu-rich type, Au-rich type, and Pb-Zn-rich type in terms of metal contents. Pyrite and chalcopyrite of early stage are replaced by galena and sphalerite along the fissure or interface. Electrum is closely associated with bismuthinite and galena precipitated in the late stage of mineralization. The metal contents of this area range from 0.1 to 4.3%Cu, from 0.1 to 12.3%Pb, and from 1.0 to 6.7%Zn, and also the concentration of gold is up to 2.25g/t. The isotopic data of host rock shows constant value as 19.9ñ for oxygen, 5.8ñ for carbon, but the isotopic values of alteration zone range from 9.4 to 15.4ñ for oxygen and from -0.3 to 0.4ñ for carbon, which means the ore fluid altered by interaction with host rock including temperature and pressure change. Using the sulfur geothermometer, the mineralization temperature shows a range from 192 to 277°C. It seems that Au-rich manto-type polymetallic mineralization is related to later low temperature hydrothermal fluid originated from distal intrusives.