Multiple generations of mafic-ultramafic rocks from the Hongseong suture zone, western South Korea: Implications for the geodynamic evolution of NE Asia

摘要

Dismembered mafic and serpentinized ultramafic bodies within the Hongseong suture zone of the Gyeonggi massif, southwestern Korean Peninsula are tectonically correlated with those from the Chinese Qinling-Dabie-Sulu collisional belt We report sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon ages, detailed mineral compositions and whole rock geochemical data from the mafic rocks including edogite and garnetite from the Hongseong suture zone. The zircon U-Pb data show multiple protolith ages corresponding to Neoproterozoic (ca. 815-770 Ma), Paleozoic (ca. 310 Ma) and Middle Triassic (ca. 240 Ma). The peak high-pressure and retrograde regional intermediate-pressure metamorphic events of Middle Triassic (ca. 240-230 Ma) are also recorded in zircons from the mafic rocks in the Hongseong suture zone. The ages and P-T estimates presented in this study match well with those of the peak ultra-high-pressure metamorphism in the Sulu area of China. Our results from the Hongseong suture zone provide important insights into the geodynamic history of the NE Asian region, with evidence for both Neoproterozoic subduction and a Paleozoic to Triassic subduction/accretion event.