Mesozoic evolution of the Pakchon Basin in the NW Korean peninsula: New insights about the evolution of the Mesozoic basins along the eastern margin of the Sino-Korean Craton

The Pakchon Basin is situated in the eastern margin of the Sino-Korean Craton,NW Korean Peninsula. The basin is bounded by the NE-SW striking Chongchongang Fault to the south and the nearly N-S striking Taeryonggang Fault to the east. The sedimentary succession of this basin comprise volcanic and terrigenous sedimentary rocks. The basin has experienced five Mesozoic evolution stages as follows. In the earlier Early Cretaceous, the NNE-striking Taeryonggang Fault was developed as the Riedel shear fracture controlled by the NE-trending sinis-tral faulting. Opening of the basin was due to the NW-SE trending extension during the later Early Cretaceous, and it was firstly filled with the Lower Cretaceous andesitic porphyrite, conglomerate, sandstone and siltstone. After this extension, the sinistral movement of the main boundary faults occurred as a result of the NE-SW trending compression in the latest Early Cretaceous. Afterwards, extension of the Early Cretaceous basin by the NW-SE tension caused the depositions of the Upper Cretaceous conglomerate, sandstone siltstone and mudstone, and simultaneously, the regional counterclockwise horizontal rotation during the earlier Late Cretaceous, resulted in a distinct shape of the basin that narrows in the north and widens in the south. Lastly, during the later Late Cretaceous, Mesozoic evolution of the basin was terminated. The evolution stages were likely connected with subduction and roll-back of the Izanagi Plate, and hence, we suggest that the compres-sional and extensional motions might have frequently taken place in the eastern margin of the Sino-Korean Craton during the Cretaceous.