SHRIMP zircon geochronology, and geochemical characteristics of metaplutonic rocks from the south western Gyeonggi Block, Korea: Implications for Paleoproterozoic to Mesozoic tectonic links between the Korean Peninsula and eastern China

Abstract

The Hongseong area in the south-western Gyeonggi Block of the Korean Peninsula consists of several Precambrian complexes that were regionally metamorphosed during the Triassic collision between the North and South China Blocks. Paleoproterozoic and Neoproterozoic magmatism and Triassic regional metamorphism in the Hongseong area suggest a possible tectonic link with the Yangtze Craton in the South China Block. The early magmatism in the western Hongseong area was Neoproterozoic, while that in the eastern Hongseong area was Paleoproterozoic. Sensitive high-resolution ion microprobe (SHRIMP) U-Pb dating of zircon indicates that the Neoproterozoic igneous activity occurred at ca. 850-830 Ma. U-Pb ages of zircon cores and first metamorphic overgrowths in the Paleoproterozoic gneisses are indistinguishable (1.88-1.86 Ga), indicating that the igneous activity and early metamorphism occurred in relatively rapid succession. The geochemical signatures indicate an arc tectonic setting for both the Paleoproterozoic and Neoproterozoic rocks. The age and geochemical signatures of the Neoproterozoic magmatism can be matched with the Neoproterozoic magmatism at the margin of the Yangtze Craton before amalgamation of the Rodinian supercontitnent. The Paleoproterozoic igneous and metamorphic events may be related to the assembly of the Columbian supercontinent. Both the Neoproterozoic igneous rocks and the Paleoproterozoic orthogneisses in the Hongseong area were regionally metamorphosed in the Triassic, at ca. 235 Ma. This regional metamorphism is well correlated with metamorphism at the northern margin of the Yangtze Craton where the Qinling-Dabie-Sulu UHP metamorphic belt formed due to the Triassic collision between the Yangtze Craton and North China Blocks. Similarities in the overall age distribution and the geographic resemblance between the Hongseong area and the northern margin of the Yangtze Craton show that the Hongseong area in the south-western Gyeonggi Block was tectonically linked with the Yangtze Craton, at least since the time of Rodinia.