Episode of intense chemical weathering during the termination of the 635 Ma Marinoan glaciation

Cryogenian (∼720–635 Ma) global glaciations (the snowball Earth) represent the most extreme ice ages in Earth’s history. The termination of these snowball Earth glaciations is marked by the global precipitation of cap carbonates, which are interpreted to have been driven by intense chemical weatheri...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2016-12, Vol.113 (52), p.14904-14909
Main Authors: Huang, Kang-Jun, Teng, Fang-Zhen, Shen, Bing, Xiao, Shuhai, Lang, Xianguo, Ma, Hao-Ran, Fu, Yong, Peng, Yongbo
Format: Article
Language:English
Subjects:
Alkalinity
Carbonates
Deglaciation
Earth
Geochemistry
Glaciation
Glaciers
Ice
Ice ages
Physical Sciences
Precipitation
Sedimentation & deposition
Weathering
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Summary:Cryogenian (∼720–635 Ma) global glaciations (the snowball Earth) represent the most extreme ice ages in Earth’s history. The termination of these snowball Earth glaciations is marked by the global precipitation of cap carbonates, which are interpreted to have been driven by intense chemical weathering on continents. However, direct geochemical evidence for the intense chemical weathering in the aftermath of snowball glaciations is lacking. Here, we report Mg isotopic data from the terminal Cryogenian or Marinoan-age Nantuo Formation and the overlying cap carbonate of the basal Doushantuo Formation in South China. A positive excursion of extremely high δ26Mg values (+0.56 to +0.95)—indicative of an episode of intense chemical weathering—occurs in the top Nantuo Formation, whereas the siliciclastic component of the overlying Doushantuo cap carbonate has significantly lower δ26Mg values (
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1607712113