Paleoproterozoic glaciation: Evidence from carbon isotope record of the Hutuo Group,Wutai Mountain area of Shanxi Province,China |
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Authors: | FanFan Kong XunLai Yuan ChuanMing Zhou |
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Institution: | [1]School of Resource and Earth Science, China University of Mining and Technology, Xuzhou 221008, China [2]State Key Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing 210008, China |
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Abstract: | 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 δ 13Ccarb values in the Dashiling Formation of the Doucun Subgroup (3.2‰ to 1.0‰, VPDB); (2) a decrease in δ 13Ccarb 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 δ 13Ccarb 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. |
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Keywords: | ice age carbon isotopes Hutuo Group Paleoproterozoic Wutai Mountain Shanxi Province |
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