Paleoproterozoic glaciation: Evidence from carbon isotope record of the Hutuo Group, Wutai Mountain area of Shanxi Province, China

• 来源期刊: 科学通报(英文版)
• 学科: 地球科学
• 年，卷（期）: 2011,（27）
• 页码范围: 2922-2930
• 页数: 9页
• 分类号: P597
• 语种: 中文

摘要

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 13 C carb values in the Dashiling Formation of the Doucun Subgroup (3.2‰ to 1.0‰, VPDB); (2) a decrease in δ 13 C carb 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 13 C carb 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.