中国科学院南京地质古生物研究所机构知识库

Zhou et al. (2004) reported a zircon U-Pb isotope dilution - thermal ionization mass spectrometry (ID-TIMS) age of 662.9 +/- 4.3 Ma from the basal Datangpo Formation of the Cryogenian System in South China. It was the first zircon U-Pb age to constrain both the termination of Sturtian glaciation and the onset of Marinoan glaciation, despite its much larger uncertainty expected for modern ID-TIMS analysis. In this study, we carried out U-Pb chemical abrasion - isotope dilution - isotope ratio mass spectrometry (CA-ID-IRMS) analysis on the same sample, yielding a Pb-206/U-238 date of 659.96 +/- 0.46 Ma. Bayesian eruption age estimate indicates that the ash layer was most likely deposited at 659.23 +/- 1.24 Ma. The present study suggests that the Sturtian glaciation terminated before similar to 660 Ma. Together with previously reported radiometric dates, the precise U-Pb age presented herein helps refine the current Cryogenian chronology. (C) 2020 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights reserved.