Mineralization of Hydrothermal Ore Deposits in Relation to Chemical Variation of the Cretaceous Granitoids in the Gyeongsang Basin

경상분지내 열수광상의 광화작용과 백악기 화강암류의 화학성분 변화와의 관계

The Cretaceous granitic rocks show differences in rock types and chemical compositions according to metallogenic provinces of copper, lead zinc and molybdenum in the Gyeongsang basin. Jindong granites are of granodiorite~quartz diorite~diorite in Cu-province; Makeunsan/Yucheon-Eonyang granites, granodiorite~granite in Pb Zn-province; Onjeongri-Yeonghae granites, granodiorite~quartz diorite in Mo-province, and there is a trend that productive masses are less differenciated than barren masses in Cu and Pb-Zn provinces whereas productive masses are more differenciated than barren masses in Mo province. Metallogenic provinces are distinguishable by variations of major and trace elements. The Cretaceous granitic rocks are highest in the content of Ca, Mg and other basic major elements and lowest in the content of K and Na in Cu provicne; the variation trends are vice versa in Pb-Zn province. Trace elements such as Rb and Sr show variations related to K and Ca, and metallogenic provinces are also distinguishable by their ratios. The granitic rocks of Mo province have intermediate content of major and trace elements, but are clearly distinguishable from Jindong granites and partly overlapped by Yucheon-Eonyang granites. Chlorine content in biotites is higher in a productive mass than in a barren mass in Cu province. Therefore, the mineralogical and chemical compositions are applicable as geochemical index to distinguish the types of mineralizaion, and productive and barren masses of the Cretaceous granitic rocks in the Gyeongsang basin.