Paleogeographic Reconstructions of the East Asia Continental Margin during the Middle to Late Mesozoic: A Review

The currently available paleogeographic maps of the East Asia continental margin during the Mesozoic have been recasted in the light of the recent research results on sediments distributed in both Korea and Japan. Both the Korean Peninsula and the Inner Zone of Southwest Japan exchanged sediment supply through time during the middle to late Mesozoic, suggestive of close paleogeogrpahic relationship between the two countries at the active continental margin setting. During the latest Middle to earliest Late Jurassic the Mino-Tamba trench was developed along the southeastern Korean Peninsula, from which trench-fill sediments were sourced and to which accretionary complex was accreted. Lower Cretaceous quartzarenite clasts of the Tetori Group in the Hida marginal belt of Southwest Japan were derived from pre-Mesozoic quartzarenite strata distributed in the southern central and east central Korean Peninsula, suggesting that the Tetori Basin was located closely to the central eastern part of the Korean Peninsula at the time of deposition of quartzarenite clasts, contrary to the conventional thoughts of far distance between the two areas based on the paleomagnetic data. During the early Late Cretaceous radiolaria-bearing, chert pebbles and sands in the northern part of the nonmarine Gyeongsang Basin distributed in the southeastern Korean Peninsula were derived from uplifted Mino-Tamba accretionary complex distributed in Southwest Japan, suggesting that the Mino-Tamba terrane was land-connected with the eastern Korean Peninsula. All these new findings suggest that in contrast to the conventional thoughts the collage of tectonic blocks in Southwest Japan have assembled in post-early Late Cretaceous time.