Was the Ediacaran Shuram Excursion a globally synchronized early diagenetic event? Insights from methane-derived authigenic carbonates in the uppermost Doushantuo Formation, South China

doi:10.1016/j.chemgeo.2016.12.010

	Was the Ediacaran Shuram Excursion a globally synchronized early diagenetic event? Insights from methane-derived authigenic carbonates in the uppermost Doushantuo Formation, South China
	Cui, H (Cui, Huan); Kaufman, AJ; Xiao, SH; Zhou, CM (周传明）; Liu, XM
	2017
发表期刊	Chemical Geology
ISSN	0009-2541
卷号	450 页码:59-80
摘要	The Ediacaran Period is characterized by the most profound negative carbon isotope (delta C-13) excursion in Earth history, the Shuram Excursion. Various hypotheses - including the massive oxidation of dissolved organic carbon (DOC) in the oceans, the weathering of terrestrial organic carbon, or the release and oxidation of methane hydrates and/or expelled petroleum from the subsurface - have been proposed as sources of the C-13-depleted carbon. More recently, it has been suggested that global-scale precipitation of early authigenic carbonates, driven by anaerobic microbial metabolism in unconsolidated sediments, may have caused the Shuram Excursion, but empirical evidence is lacking. Here we present a comprehensive analysis of a Shuram-associated interval from the uppermost Doushantuo Formation in South China. Our study reveals petrographic evidence of methane-derived authigenic calcite (formed as early diagenetic cements and nodules) that are remarkably depleted in C-13- suggesting a buildup of alkalinity in pore fluids through the anaerobic oxidation of methane (AOM) - and systematically depleted in O-18 relative to co-occurring dolomite. Early authigenesis of these minerals is likely to be driven by increased microbial sulfate reduction, triggered by enhanced continental weathering in the context of a marked rise in atmospheric oxygen levels. In light of the finding of methane-derived authigenic carbonates at Zhongling, and based on our basin-scale stratigraphic correlation, we hypothesize that the marked C-13 and O-18 depletion (including their co-variation noted worldwide) in the Shuram Excursion may reflect an episode of authigenesis occurring within a sulfate-methane transition zone (SMTZ). If true, the Shuram Excursion was then a global biogeochemical response to enhanced seawater sulfate concentration in the Ediacaran ocean driven by the Neoproterozoic oxidation of surface environments. This paleo-oceanographic transition may have therefore paved the way for subsequent evolution and diversification of animals. Our study highlights the significance of an integrated approach that combines petrography, mineralogy, and texture-specific micro-drilling geochemistry in chemostratigraphic studies. (C) 2016 Elsevier B.V. All rights reserved.
关键词	Shuram Excursion Authigenic carbonate Early diagenesis Ediacaran Period Sulfate-Methane Transition Zone (SMTZ) Anaerobic Oxidation of Methane (AOM) Neoproterozoic Oxygenation Event (NOE) delta C-13 and delta O-18 co-variation
DOI	10.1016/j.chemgeo.2016.12.010
收录类别	SCI
语种	英语
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000394473600005
出版者	ELSEVIER SCIENCE BV
文献类型	期刊论文
条目标识符	http://ir.nigpas.ac.cn/handle/332004/13712
专题	中国科学院南京地质古生物研究所其他
通讯作者	Cui, H (Cui, Huan)
推荐引用方式 GB/T 7714	Cui, H ,Kaufman, AJ,Xiao, SH,et al. Was the Ediacaran Shuram Excursion a globally synchronized early diagenetic event? Insights from methane-derived authigenic carbonates in the uppermost Doushantuo Formation, South China[J]. Chemical Geology,2017,450:59-80.
APA	Cui, H ,Kaufman, AJ,Xiao, SH,Zhou, CM ,&Liu, XM.(2017).Was the Ediacaran Shuram Excursion a globally synchronized early diagenetic event? Insights from methane-derived authigenic carbonates in the uppermost Doushantuo Formation, South China.Chemical Geology,450,59-80.
MLA	Cui, H ,et al."Was the Ediacaran Shuram Excursion a globally synchronized early diagenetic event? Insights from methane-derived authigenic carbonates in the uppermost Doushantuo Formation, South China".Chemical Geology 450(2017):59-80.