Detrital Zircon Geochronology of the Zongwulong Group in the Eastern Segment of the Zongwulong Tectonic Belt and Its Tectonic Significance

The Zongwulong tectonic belt is situated at the northeastern margin of the Tibetan Plateau, constrained between the South Qilian, North Qaidam margin, and West Qinling tectonic belts. Its tectonic evolution is closely associated with the northeastern Tethyan tectonic domain. Current academic debates persist regarding the formation age of the Zongwulong Group, its material provenance, and the evolutionary history of the tectonic belt. This study focuses on the clastic rocks of the Zongwulong Group in the eastern segment of the tectonic belt, employing detrital zircon U-Pb geochronology, trace element analysis, and Hf isotopic composition investigations. Results demonstrate that the depositional age of the Zongwulong Group postdates the Middle Permian. Detrital zircon U-Pb ages predominantly cluster in the Early Paleozoic and Late Paleozoic, with prominent peaks at ～431 Ma and ～269 Ma. Trace element characteristics indicate that these detrital zircons originated from arc-related continental crustal sources, correlating with magmatic activities in the southern Wulan-Qinghai Nanshan region. Comparative analysis of age spectra reveals distinct tectonic evolutionary processes between the eastern and western segments of the Zongwulong belt. The eastern segment developed a limited oceanic basin, potentially representing the northernmost branch of the Paleo-Tethys Ocean, whereas the western segment shows no evidence of oceanic basin development.