The studied area located between southeastern zone of Ogcheon Geosynclinal belt and northwestern margin of Ryeongnam massif is composed of various igneous rock bodies with several geologic time. The geochemical and geochronological features, and igneous activity of these igneous rocks are as follows. Igneous rocks of the studied area consist of Granite gneiss of Devonian, Foliated granites and Namweon granites of Triassic, Diorite-gabbro of Jurassic and Granite prophyry of Cretaceous. Foliated granites is divided into three rock types(Sunchang foliated granite, Leuco foliated granite and Two mica foliated granite) in terms of mineralogical and field evidence. Foliated texture of these rock types is considered to be formed by strong mylonitization during several orogenies. Namweon granites is classified into four rock types(Hornblende-biotite granodiorite, Pophyritic granodiorite, Biotite granodiorite and Two mica granite). The general trend of the chemical composition of these igneous rocks suggests that each granitic rock is aggregate of differentiated products by fractional crystallization and contamination. The geochronological data for igneous rocks of the studied area were undertaken by K-Ar method of hornblende in Sunchang foliated granites, Hornblende-biotite granodiorite and Diorite-Gabbro. These data come to an coincidence with igneous activity which were proposed by O.J. Kim (1975), that is, they correspond to Sunchang foliated granite(198±9.9 Ma) and Namweon granite(203±10.2 Ma) of products of Songrim Distrubance, and to Diorite-gabbro(180.7±9.0 Ma) of DaebO Orogeny.
Kim et al. (Tue,) studied this question.