干旱区生态环境知识资源中心(Arid): Positive cerium anomalies imply pre-GOE redox stratification and manganese oxidation in Paleoproterozoic shallow marine environments

Arid

DOI	10.1016/j.precamres.2020.105767
	Positive cerium anomalies imply pre-GOE redox stratification and manganese oxidation in Paleoproterozoic shallow marine environments
	Warke, Matthew R.; Strauss, Harald; Schroder, Stefan
通讯作者	Warke, MR
来源期刊	PRECAMBRIAN RESEARCH
ISSN	0301-9268
EISSN	1872-7433
出版年	2020
卷号	344
英文摘要	The Paleoproterozoic Koegas Subgroup (Transvaal Supergroup, South Africa) was deposited in the immediate prelude to the Great Oxidation Event (GOE), and can therefore shed light on oceanic paleoredox conditions just before atmospheric oxidation. Manganese enrichments of similar to 16 wt% in diagenetic kutnahorite horizons suggest that Mn2+ oxidation occurred, either by free O-2 or by an ancient photosystem. Iron and molybdenum isotope trends also support the existence of a Mn(4+ )oxide sediment flux, suggesting that the Koegas basin may have been redox stratified. Evidence from detrital and authigenic pyrite with mass-independently fractionated sulfur isotopes, however, suggests that the atmosphere was devoid of oxygen. To resolve this contradiction, this paper presents new constraints on pathways of Mn2+ oxidation from field, petrographic, stable isotope, and rare earth element and yttrium (REYSN) analysis of stromatolitic carbonates from the upper Koegas Subgroup. Ferroan dolostones and limestones preserve marine REYSN arrays with positive Ce-SN anomalies. These differences are explained by a redox stratified basin, whereby Mn2+ and CO3+ are oxidized at a redoxcline and Ce is adsorped onto sinking Mn oxide particles. Mn oxide particles and a negative Ce anomaly from the oxidized upper water column are transferred into carbonates accumulating above the redoxcline. Diagenetic fluids later reduce the Mn oxides to kutnahorite. Below the redoxcline, reduction of Mn oxides enriches carbonates in Mn and a positive Ce anomaly. This contribution adds evidence for the development of oxygen oases and redox-stratified basins before the GOE. Redox stratification was best developed during transgressions. During regressions, a deltaic system prograded into the Koegas Basin. High sedimentation rates likely allowed for preservation of detrital pyrite only in the deltaic sandstones, thus explaining the contradictory geochemical evidence. No previously unknown ancient photosystem of Mn oxidation is required to explain Mn oxidation.
英文关键词	Koegas Transvaal Great Oxidation Event Rare Earth Elements Cerium
类型	Article
语种	英语
收录类别	SCI-E
WOS记录号	WOS:000536778900011
WOS关键词	RARE-EARTH-ELEMENTS ; SOUTH-AFRICA IMPLICATIONS ; HOTAZEL IRON-FORMATION ; TRANSVAAL SUPERGROUP ; GRIQUALAND WEST ; TRACE-ELEMENT ; HEAVY CARBON ; MN OXIDES ; OXYGEN ; MOLYBDENUM
WOS类目	Geosciences, Multidisciplinary
WOS研究方向	Geology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/324583
作者单位	[Warke, Matthew R.; Schroder, Stefan] Univ Manchester, Sch Earth & Environm Sci, Basin Studies & Petr Geosci, Manchester M13 9PL, Lancs, England; [Warke, Matthew R.] Univ St Andrews, Sch Earth & Environm Sci, St Andrews KY16 9AL, Fife, Scotland; [Strauss, Harald] Westfalischen Wilhelms Univ Munster, Geol Palaontol Inst, Correnstr 24, D-48149 Munster, Germany
推荐引用方式 GB/T 7714	Warke, Matthew R.,Strauss, Harald,Schroder, Stefan. Positive cerium anomalies imply pre-GOE redox stratification and manganese oxidation in Paleoproterozoic shallow marine environments[J],2020,344.
APA	Warke, Matthew R.,Strauss, Harald,&Schroder, Stefan.(2020).Positive cerium anomalies imply pre-GOE redox stratification and manganese oxidation in Paleoproterozoic shallow marine environments.PRECAMBRIAN RESEARCH,344.
MLA	Warke, Matthew R.,et al."Positive cerium anomalies imply pre-GOE redox stratification and manganese oxidation in Paleoproterozoic shallow marine environments".PRECAMBRIAN RESEARCH 344(2020).