The Study on the Igneous Activity in the Southeastern Zone of the Ogcheon Geosynclinal Belt , Korea(Ⅱ) - with the Igneous Activity between Jinan and Naju -
옥천지향사대 동남대에서의 화성활동(Ⅱ) -진안 - 나주사이 지역을 중심으로
Main aspects of this study are to clarify igneous activity of igneous rocks, which is a member of various intrusives and volcanics exposed in the SE-zone of Ogcheon Geosynclinal belt, one of basement of Korean peninsula. Igneous rocks of study area along marginal area between SE-zone and C-zone of Ogcheon Geosynclinal belt consist of Pre-Cambrian orthogneiss, Triassic foliated granites and Namweon granites, Jurassic diorite-gabbro and granites, and Cretaceous granites and volcanics. Foliated granites in so-called Honam shear belt of study area is divided into four rock units based on the geologic age, mineralogy and texture : Daegang foliated granite, foliated hornblende biotite grandiorite, foliated biotite granodiorite and foliated two mica granite. Foliation of foliated granites generated by dextral strike slip movement at deep ductile shear zone. The individual synchronous plutons plottes on Harker diagram show mostly similar trend to the Daly's values. Each plots of the foliated granites, Jurassic granites and Cretaceous igneous rocks concentrate near trend of talc-alkali rock series on the AMF diagram. Igneous rocks of study area vary wide range in total REE content(83.27-377.49ppm) show LREE enriched than HREE in REE amount, and LREE have more steep negative slope in Eu(-) anomaly. From the date mentioned above, it is concluded the synchronous plutons which composed of several rock facies is considered to formed by differentiation of a series of magma. Geochronological episodes of igneous activity from early proterozoic to late Cretaceous between Jinan and Naju are two more Pre-Cambrian Orogenies, Songrim Disturbance, Daebo Orogeny and Bulkuksa Disturbance.