Continental origin of the Bibong eclogite, southwestern Gyeonggi massif, South Korea

Eclogite is a high-pressure (HP) metamorphic rock that provides important information about the subduction of both continental and oceanic crusts. In this study we present SHRIMP zircon U-Pb isotopic data for a suite of the basement gneisses to investigate the origin of the Proterozoic Bibong eclogite in the Hongseong area, South Korea. Zircon grains from the basement felsic gneisses yielded Paleoproterozoic protolith ages ranging from ca. 2197 to 1880. Ma, and were intruded by syenite at ca. 750. Ma. A HP regional metamorphic event of Triassic age (ca. 255-227. Ma) is recorded in the zircon rims of the country rocks, which is also observed in the zircons from the eclogite. The contacts between the Bibong eclogite and its host rocks support an origin for the Proterozoic protoliths, indicating continental intrusions. The Hongseong area thus preserves evidence for the Triassic collision, indicating a tectonic linkage among the northeast Asian continents.