Mineralization Associated with Mesozoic Felsic Magmatism in Japan and Korea

Abstract

The characteristics of mineral deposits of granitic affinity in Japan, of mostly Cretaceous and Miocene age, have been well established by recent work. In the Korean peninsula, the Jurassic Daebo and Cretaceous Bulgugsa granitic activities are recognized, and Au-Ag, W-Mo-Bi, Cu-Zn-Pb, Fe(-Cu) and F deposits are formed in genetical association with these activities. Some geologic evidence, besides K-Ar age determination data, suggests that major Korean W-Mo-Bi, Cu-Zn-Pb and F mineralization occurred in Cretaceous time. This tentative conclusion makes it possible to correlate the metallogenic features of Japan and Korea for Cretaceous time. The distribution pattern of Cu and Zn-Pb deposits in both countries seems to be related to the present erosion level, that is, Cu is associated with plutonic activity, while Zn-Pb is with hypabyssal to effusive activity. Major fluorite deposits tend to be formed in shallow environments, perhaps related to subaerial volcanic activity. No clear correlation of W-Mo mineralization could be obtained between the two countries. To get the exact position of the southwestern Japan arc in Cretaceous time, reconstruction of the arc relative to the Korean peninsula is attempted (Fig.4). The arc arrived at its present position by clockwise rotation around the Hokusatsu bend in Tertiary time as a result of the opening of the Japan Sea.