Abundances of Trace Elements of the Granitic Rocks and their Tectonic Implication in Daejeon-Gongju Area

The studied area is located in northwestern part of Ogcheon geosyncline belt. The area is composed of the porphyritic granitic gneiss, meta-sedimentary rocks, granitic rocks (schistose granodiorite, biotite granite, two-mica granite, porphyritic granite, pink feldspar granite), gabbro, dioritic rock and dike rocks. Geochronological data of the rocks suggest that the major igneous activities in this area had been successively continued from the Triassic to the Cretaceous. Regarding the field occurrence, petrological and geochemical characteristics of them, granitic rocks were formed from progressive partial melting of relatively homogeneous meta-pelitic rocks, at the compressional plate margin, that is, the intermediate stage of the island arc or normal continental arc. Granitic rocks are relatively alkali poor salic and belong to “S-type” or ilmenite series.