Mesozoic detrital zircon U-Pb ages of modern river sediments in Korea: Implications for migration of arc magmatism in the Mesozoic East Asian continental margin

摘要

U-Pb ages of detrital zircons collected from the sediments of seven major South Korean rivers were analysed to infer the temporal and spatial distribution of Mesozoic arc magmatism related to the subduction of the palaeo-Pacific plates. Mesozoic detrital zircon U-Pb ages indicate continuous arc magmatic activity in the Korean Peninsula throughout the Mesozoic era (249-72Ma), except for a magmatic gap during 120-162Ma, with NW-SE spatial migration of the arc magmatic centres: trenchward migration in both the Triassic and the Cretaceous periods, and inland-directed migration in the Jurassic period. A comparison of these results with the magmatic ages in the adjacent regions such as northeastern China and southwestern Japan suggests that subduction modes of the palaeo-Pacific plates were changed in the Mesozoic East Asian continental margin due to buoyancy differences caused by the subduction of the Farallon-Izanagi plate ridge or oceanic plateaus and their subducting location shifting with time.