关键词: 滹沱群, 冰碛岩, 休伦冰川事件, 大氧化事件, 碎屑锆石年龄, 华北克拉通

Abstract: The metamorphosed diamictite in the Sijizhuang Formation of the Hutuo group in Shanxi Province shows the characteristics of a polymictic origin. They are barely sorted, poorly rounded, and with striated and faceted clasts and dropstone structures, suggesting a glaciomarine environment during the Paleoproterozoic glaciation in the North China Craton. Our research show that the U-Pb ages of detrital zircons from different lithofacies sediments of the Sijizhuang Formation peaked at around 2.5 Ga. The youngest zircons from two diamictite samples from the lower portion of the Sijizhuang Formation yielded the youngest concordant ages of 2440±40 and 2400±23 Ma, respectively, and sandstone from the upper layer of the Sijizhuang Formation yielded a youngest concordant age of 2121±22 Ma. Thus the detrital zircon U-Pb ages  constrain the glaciation in Wutai Shan to be between 2.4 and 2.1 Ga, i.e., the time of  the HGE (Huronian Glaciation Event). However, the youngest zircon age of 2.1 Ga suggests that the glaciation in North China Craton did not end until 2.1 Ga. The Sijizhuang Formation was not deposited from mountain glacier but on a continental margin. The Dashiling Formation above the Sijizhuang Formation was deposited during 2.12 to 2.08 Ga, showing positive carbonate carbon isotopic excursion that coincided with the global positive carbon isotopic excursion event (LJE: Lomagundi-Jatuli Event). The record of red beds in the Qingshicun Formation occurred about 2.08 Ga, coinciding with the beginning of global evolution of red beds. Thus, the Hutuo Group in the North China Craton records a complete sequence of the Great Oxidation Event.

Key words:  Hutuo Group, glacial diamictite, Huronian Glaciation Event, Great Oxidation Event, detrital zircon age, North China Craton