A Geochemical Study on Jindong Granites in Relation to Copper Ore Deposits in Gyeongsang Basin

경상분지내 동광상 관련 진동화강암류에 대한 지화학적 연구

Jindong Granites are plotted mainly in the region of granodiorite~diorite of the Streckeisen's diagram, while Yucheon-Eonyang Granites and Onjonri Granites in the region of monzo-granite and monzo-granite~granodiorite, respectively. Jindong Granites show a differenciation trend of calc-alkaline magma, and its magmatic evolution from intermediate to acidic rocks, which might form mineralizing solution, is consistant with the general path of the Cretaceous granitic rocks including Yucheon-Eonyang Granites and Onjongri Granites. The differenciation index (D.I.) is 35~80 for Jindong Granites, which is lower than 85~95 of Yucheon-Eonyang Granites and is partly overlapped by 67~84 of Onjongri Granites. There is clear difference in content of some major and trace elements between Jindong Granites of Cu province and the other granitic rocks of Pb-Zn and Mo provinces. Between these metallogenic provicnes, Cu content is high in Jindong Granites near Haman-Gunbuk mineralized zone, while Pb and Zn are relatively abundant in Yucheon-Eonyang Granites and Mo in Onjongri Granites. Therefore, Jindong Granites of the Cu province are distinguishable by chemical compositions and their related geochemical characteristics from the other Cretaceous granitic rocks of Pb-Zn and Mo provinces. However, the content of Cu and Cl in biotite is applicable to distinguish a productive phase from a barren phase of Jindong Granites, because Cu and Cl show a trend to be concentrated in biotite of Jindong Gratites in the Haman-Gunbuk mineralized zone.