Abstract

The Songbong Formation (so-called Bangrim Group), correated to the lower part of Choseon Supergroup, unconformably overlies the Precambrian Gyeonggi massif at northeastern tip of the Ogcheon belt. The contact relationship between the Choseon Supergroup and the Yeongnam massif is also known as an unconformity at northeastern part of the Ogcheon belt. It implies that the Gyeonggi and Yeongnam massifs were probably connected each other before the Early Paleozoic. Three deformational phases are recognized in the study area. The first phase is the north-northeastward ductile thrusting, which places Precambrian granite of the Gyeonggi massif over the Paleozoic rocks of the Ogcheon belt. The second phase is characterized by the southeastward thrusting and deformation partitioning along the Nuruhaji compartment fault. The third phase is the reactivation of the Nuruhaji Fault into dextral strike-slip fault with over a few kilometers displacement.

Keywords Songbong Formation, Bangrim Group, Ogcheon belt, unconformity, deformation partitioning