气候变化领域集成服务门户(CCPortal): Formation of large carbonate concretions in black cherts in the Gufeng Formation (Guadalupian) at Enshi, South China

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DOI	10.1111/gbi.12362
	Formation of large carbonate concretions in black cherts in the Gufeng Formation (Guadalupian) at Enshi, South China
	Wei H.; Tang Z.; Qiu Z.; Yan D.; Bai M.
发表日期	2020
ISSN	14724677
起始页码	14
结束页码	30
卷号	18 期号:1
英文摘要	The formation of carbonate concretions is a cementation process which passively infills the pore spaces within sediments. They record the original environments of deposition and diagenetic conditions of the host rocks. Little is known about the precise mechanisms responsible for the precipitation of carbonate concretions. The most common host rocks are mudstones/shales, sandstones, and limestones. This study presents an example of large carbonate concretions from an unusual host rock, the black bedded cherts of the Gufeng Formation (Guadalupian) at Enshi on the northern Yangtze Platform, South China. Petrographic observations (X-ray diffraction, optical microscopy, scanning electron microscopy) and multiple geochemical analyses (pyrite- and carbonate-associated-sulfate (CAS)-sulfur isotopes, carbon isotopes) indicate that (a) the studied carbonate concretion are mainly composed of micritic calcite with subordinate dolomite; (b) the concretions may have been mainly formed in the bacterial sulfate reduction (BSR) zone during very early diagenesis near the sediment–water surface; (c) the paleo-bottom water overlying the sediments during formation of the concretions was mainly euxinic; and (d) the growth of the studied concretions proceeded via a pervasive model, where later cementation phase initiated in the lower part of the concretions and progressed upward. © 2019 John Wiley & Sons Ltd
关键词	bacterium carbonate system cementation chert concretion deposition diagenesis host rock infill petrography precipitation (chemistry)pyrite reduction stable isotope sulfate China Enshi Hubei Yangtze Platform Bacteria (microorganisms)carbon carbonic acid sulfur China sediment Carbon Isotopes Carbonates China Geologic Sediments Sulfur Isotopes
语种	英语
来源机构	Geobiology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/133215
推荐引用方式 GB/T 7714	Wei H.,Tang Z.,Qiu Z.,et al. Formation of large carbonate concretions in black cherts in the Gufeng Formation (Guadalupian) at Enshi, South China[J]. Geobiology,2020,18(1).
APA	Wei H.,Tang Z.,Qiu Z.,Yan D.,&Bai M..(2020).Formation of large carbonate concretions in black cherts in the Gufeng Formation (Guadalupian) at Enshi, South China.,18(1).
MLA	Wei H.,et al."Formation of large carbonate concretions in black cherts in the Gufeng Formation (Guadalupian) at Enshi, South China".18.1(2020).