U-PB AND HF ISOTOPE ANALYSIS OF DETRITAL ZIRCONS FROM THE MIDDLE PALEOZOIC SUCCESSIONS IN THE KOREAN PENINSULA: TECTONIC IMPLICATIONS

The Hongseong–Imjingang Belt has been recently defined as the most probable collisional orogenic belts in the Korean Peninsula, where the area has been tectonically correlated to the Central China Orogenic Belt in terms of collisional tectonics. The belt is bounded by two Precambrian basements (i.e. the Nangrim and Gyeonggi massifs), and is the only distribution of the Middle Paleozoic successions in Korean Peninsula. Therefore, the provenance studies based on the detrital zircon signatures from these sedimentary rocks, combined with data from adjacent basements, might help to provide important information to reconstruct Paleozoic tectonic evolution of East Asia. In this study, we present SHRIMP and LA–(MC)–ICP MS U-Pb ages and Hf isotopes of detrital zircon grains from the metasedimentary rocks of the Taean and Misan formations in the southern and northern areas of the Hongseong-Imjingang Belt, respectively. Based on the internal structures of the zircons from all the samples, most of them were derived from igneous source rocks, showing dominant Early Neoproterozoic and Silurian-Devonian ages. The maximum deposition ages of these rocks were estimated from the youngest concordant detrital zircons, indicating that the Taean Formation was deposited slightly later than the Misan Formation. Ages and Hf isotope signatures of dominant Early Neoproterozoic and Silurian-Devonian detrital zircon populations reflect magmatic history involving juvenile input and crustal reworking. In contrast, the minor magmatic detrital zircon populations with Paleoproterozoic ages imply that much of the detritus were not derived from the Gyeonggi or Nangrim massifs. The results, integrated with U-Pb and Hf isotope data from other parts of the Korean Peninsula and the Chinese cratons, will eventually help to understand the Middle Paleozoic evolution of the Korean Peninsula in relation to the tectonic history of East Asia during the Paleozoic in age.