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Palaeoproterozoic global glaciation (∼2.3 Ga) may have been the first 'snowball' Earth event in Earth history. North China has well-exposed sedimentary deposits of this time period with minimal postdepositional alteration. Sedimentary evidence of a glaciation event has been lacking, however. Here we analyzed carbon isotope composition of the Paleoproterozoic Hutuo Group (2.5-2.2 Ga) in the Wutai Mountain area, Shanxi Province, North China. Our data show, in an older to younger chronostratigraphic order, (1) positive δC values in the Dashiling Formation of the Doucun Subgroup (3.2‰ to 1.0‰, VPDB); (2) a decrease in δC values from the Wenshan Formation to the middle Daguandong Formation (from 2.0‰ to-1.2‰), during which time the occurrence of stromatolites declined; (3) a pronounced negative excursion in the upper Daguandong Formation, at the boundary of the Daguandong and Huaiyincun formations (from 1.4‰ to −3.3‰), where stromatolites disappeared; and (4) a gradual increase of δC values in the Beidaxing and Tianpengnao formations (from −1.2‰ to 1.4‰), during which time stromatolites returned. We argue that the negative carbon isotope excursion recorded from the Jian'ancun Formation to the middle Daguandong Formation of the Hutuo Group may have been North China's response to the Palaeoproterozoic global glaciation. [ABSTRACT FROM AUTHOR]

• Well-persevered Paleoproterozoic microfossils described and illustrated. • A new genus of Acritarch, Dongyesphaera , is established. • Morphological diversity of microfossils increased through the Paleoproterozoic. • Evidence for the earlier occurrence of metabolic activity in eukaryotic protists. The Paleoproterozoic Hutuo Group is well-developed and distributed in the Wutai Mountains in the Xinzhou area of Shanxi Province, North China. Its middle part - the Dongye Subgroup is more suitable for obtaining microfossils in deposited sediments characterized with sandstone or slate in the lower part, and upward into interbedded sandstone, carbonate with stromatolites and phyllite. Based on recent zircon dating, the Hutuo Group was deposited around 2150–1950 Ma. In this study, eight morphological genera of microfossils, including the spheroid and filamentous cyanobacteria Eoentophysalis , Sphaerophycus , Siphonophycus , Pseudodendron , and the acritarchs Dictyosphaera , Dongyesphaera gen. nov., Leiosphaeridia , Satka were identified from the Wenshan, Hebiancun and Tianpengnao Formations of the Dongye Subgroup. The identified microfossils reveal that eukaryotic protists exercised metabolic activities rarely observed to have occurred in what are thought to have been suitable environments. [ABSTRACT FROM AUTHOR]