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

doi:10.1073/pnas.1607712113

CORC > 北京大学 > 地球与空间科学学院

	Episode of intense chemical weathering during the termination of the 635 Ma Marinoan glaciation
	Huang, Kang-Jun ; Teng, Fang-Zhen ; Shen, Bing ; Xiao, Shuhai ; Lang, Xianguo ; Ma, Hao-Ran ; Fu, Yong ; Peng, Yongbo
刊名	PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
	2016
关键词	snowball Earth magnesium isotopes cap carbonate chemical weathering South China MAGNESIUM ISOTOPE FRACTIONATION NEOPROTEROZOIC SNOWBALL EARTH SOUTH CHINA OCEAN ACIDIFICATION CAP CARBONATE DOUSHANTUO FORMATION ATMOSPHERIC CO2 BREAK-UP SEAWATER AFTERMATH
DOI	10.1073/pnas.1607712113
英文摘要	Cryogenian (similar to 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 delta Mg-26 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 delta Mg-26 values (<+0.40), suggesting moderate to low intensity of chemical weathering during cap carbonate deposition. These observations suggest that cap carbonate deposition postdates the climax of chemical weathering, probably because of the suppression of carbonate precipitation in an acidified ocean when atmospheric CO2 concentration was high. Cap carbonate deposition did not occur until chemical weathering had consumed substantial amounts of atmospheric CO2 and accumulated high levels of oceanic alkalinity. Our finding confirms intense chemical weathering at the onset of deglaciation but indicates that the maximum weathering predated cap carbonate deposition.; Natural Science Foundation of China [41602343, 41272017, 41322021]; State Key Laboratory of Palaeontology and Stratigraphy Open-lab Grant [153103]; US National Science Foundation [EAR-1340160, EAR-1528553]; SCI(E); ARTICLE; bingshen@pku.edu.cn; 52; 14904-14909; 113
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/457983]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Huang, Kang-Jun,Teng, Fang-Zhen,Shen, Bing,et al. Episode of intense chemical weathering during the termination of the 635 Ma Marinoan glaciation[J]. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA,2016.
APA	Huang, Kang-Jun.,Teng, Fang-Zhen.,Shen, Bing.,Xiao, Shuhai.,Lang, Xianguo.,...&Peng, Yongbo.(2016).Episode of intense chemical weathering during the termination of the 635 Ma Marinoan glaciation.PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA.
MLA	Huang, Kang-Jun,et al."Episode of intense chemical weathering during the termination of the 635 Ma Marinoan glaciation".PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA (2016).