Rodinia supercontinent assembly in the southeastern North China Craton: Detrital zircon evidence from the late Ediacaran Fengtai Formation

Abstract

The position of the North China Craton (NCC) within Rodinia remains debated due to the notable absence of magmatic and orogenic records associated with the Rodinia assembly. Nevertheless, the discovery of abundant Grenvillian-aged detrital zircons from the late Ediacaran Fengtai Formation diamictites in the southeastern NCC provides a significant opportunity to evaluate the NCC’s affiliations with Rodinia. Detrital zircon U–Pb–Hf isotopic analyses reveal distinct age patterns of the Fengtai Formation in the Bagongshan and Sishilichangshan areas. The Fengtai Formation in the Bagongshan area is notable for its Mesoproterozoic–Neoproterozoic transition zircons, exhibiting a prominent age peak at approximately 0.99 Ga and subsidiary peaks at about 1.19 Ga, 1.43 Ga, 1.65 Ga, 1.92 Ga, and 2.50 Ga. Conversely, the diamictite in the Sishilichangshan area is marked by Neoarchean–Paleoproterozoic and secondary Mesoproterozoic zircons, featuring a primary age peak at about 2.04 Ga and minor peaks at approximately 0.90–1.00 Ga, 1.12–1.48 Ga, 1.87 Ga, 2.31 Ga, and 2.46 Ga. The Fengtai Formation sediments were derived from the late Mesoproterozoic–early Neoproterozoic cover and/or Archean–Paleoproterozoic basement in the southeastern NCC. The Neoarchean–Paleoproterozoic zircons are attributed to the basement rocks and/or the cover’s clastic rock units, whereas the Mesoproterozoic zircons represent recycled detritus from the cover’s clastic rock units. Furthermore, the Mesoproterozoic–Neoproterozoic transition zircons are interpreted as recycled tuffaceous components from the cover’s carbonate rock units. The elemental signatures of these transition zircons suggest that the associated felsic magmatic activity occurred in a continental arc orogenic setting. Notably, the declining trend of zircon ε_Hf(t) values from 1385 to 778 Ma is indicative of the presence of an interior orogenic system. These lines of evidence support the hypothesis of Grenvillian-aged orogenesis occurring in southeastern NCC, thereby affirming the NCC’s involvement in the Rodinia assembly, particularly the southeastern NCC–northwestern Laurentia connection, as demonstrated through paleomagnetic data and provenance analyses of the pre-Cryogenian cover.