Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

The geology of the study area consists of Cretaceous andesitic and rhyolitic rocks, fine grained biotite granite and alluvium. The andesitic rocks are broadly distributed in the western side of the study area, and often occur as dykes in the surface and underground. The andesitic rocks are plotted in the field of basalt to dacite, calc-alkaline and I-type series based on the chemical compositions and oxygen isotopic compositions of the andesitic rocks. Andesitc rocks were suffered a weak hydrothermal alteration on the basis of chemical compositions such as SiO2, Na2O and K2O contents, gold content variation (4ppb～24ppb), and oxygen isotopes(δ18O: +1.3 to +4.1‰) and hydrogen isotopes (δD: -88.9 to -101.1‰). These results show a similar trend in the differentiation and occurrence of the Gyeongsang basin andesitic rocks. Gold contents of the andesitic rocks range from 4ppb to 24ppb (av.: 8.7 ppb), and they show a tendency to increase as SiO2 contents (55.9 to 69.5%) increase. Gold contents have positive correlations with S, Sb, Pb and Se contents.