Mudstones from the topmost part of the Datangpo Formation in the Zouma area, western Hubei: LA-ICP-MS zircon U-Pb dating and its geological implications

In the geological history of the assembly and breakup of the supercontinent Rodinia on the Earth during the Neoproterozoic, there once occurred two phases of global glacial events in the Sturtian and Marinoan epoches. Previous studies of isotope ages show that the initiation and termination of the Sturtian glacial epoch are dated at 717 Ma and 660 Ma, while the termination of the Marinoan glacial epoch is dated at 635 Ma. However, the initiation of the Marinoan glacial epoch remains uncertain. The tillites from the Nanhuan Gucheng Formation and Nantuo Formation in southern China respectively represent the depositional records of the Sturtian and Marinoan glacial deposits, and the Datangpo Formation is represented by the interglacial deposits. The present paper reports the LA-ICP-MS zircon U-Pb age determinations of the mudstones from the topmost part of the Datangpo Formation in the Bajiaohe section, Zouma area, western Hubei. 62 spots of 62 zircon grains give 60 concordia ages (concordency >90%) ranging between 651 Ma and 2435 Ma, of which 52 zircon U-Pb ages vary from 751 Ma to 851 Ma, with the peak age of about 794 Ma. The youngest zircon U-Pb age is in general agreement with that reported by the predecessors in the adjacent areas, and thus the initiation of the Marinoan glacial epoch may be deduced to be later than 651 Ma. The detrital zircons have the Yangtze affinity, and probably originated from the central Hubei palaeocontinent and northern Yangtze landmass. The peak age of about 850 Ma within the main age range of 751 Ma to 851 Ma may record the collision and amalgamation events occurred in the Yangtze platform and Cathaysia fold zone, while the peak ages of about 820 Ma, 800 Ma and 760 Ma may record the episodic magmatism associated with the breakup of the supercontinent Rodinia.