Origin of bedded chert and organic matter accumulation in the Dalong Formation of Upper Permian in western Hubei Province

	Origin of bedded chert and organic matter accumulation in the Dalong Formation of Upper Permian in western Hubei Province
	Yu Hao 1,2; Chen DaiZhao 1; Wei HengYe 1,2; Wang JianGuo 1
刊名	ACTA PETROLOGICA SINICA
	2012-03-01
卷号	28 期号:3 页码:1017-1027
关键词	Late Permian Bedded chert Organic accumulation Oceanic anoxia Western Hubei
ISSN号	1000-0569
文献子类	Article
英文摘要	Widespread organic-rich sediments, regarded as the important source rocks, were deposited in South China during the Late Permian, a key period marked by fundamental environmental changes and biotic turnovers. This study focus on the organic-rich siliceous rocks in the Dalong Formation deposited in an intrashelf basin in western Hubei, to explore the mechanisms of silica precipitation and organic accumulation using pyrite morphology and multiple geochemical proxies. The relative high Al/Fe ratios (average 0.79) and low Mn/Ti ratios(average 0.21) favor a biogenic-dominant origin for silica precipitation, instead of a hydrothermal origin, in the intrashelf basin. The Sigma REEs are positively correlated with Al2O3 contents, suggesting that influx of terrigenous material played an important role on the formation of the chert. Relatively high ratios of U/Th (> 1.25) and V/ (V + Ni) (> 0.60) in the chert suggest an anoxic water column in which silica precipitated. Measurement of framboid pyrite size reveals that most of the pyrite framboids (64% similar to 89%) are less than 5 mu m in diameter, suggesting an extremely anoxic, even euxinic environment. Moreover, the enrichments of U, V and Mo and depletion of Ni and Cu suggest that oceanic anoxia resulted from oceanic stratification due to sluggish water circulation. No correlation between TOC contents and Ba/Al values suggests organic accumulation was mainly controlled by the redox condition of water column, rather than by primary productivity.
WOS关键词	EMEISHAN FLOOD BASALTS ; NORTH-ATLANTIC OCEAN ; DEPOSITIONAL ENVIRONMENT ; FRAMBOIDAL PYRITE ; SEDIMENTARY-ROCKS ; WATER-COLUMN ; BLACK SHALES ; RARE-EARTH ; SULFUR ; CARBON
WOS研究方向	Geology
语种	英语
出版者	SCIENCE PRESS
WOS记录号	WOS:000303640700029
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/84246]
专题	中国科学院地质与地球物理研究所
通讯作者	Yu Hao
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Petr Resources Res, Beijing 100029, Peoples R China 2.Chinese Acad Sci, Grad Univ, Beijing 100049, Peoples R China
推荐引用方式 GB/T 7714	Yu Hao,Chen DaiZhao,Wei HengYe,et al. Origin of bedded chert and organic matter accumulation in the Dalong Formation of Upper Permian in western Hubei Province[J]. ACTA PETROLOGICA SINICA,2012,28(3):1017-1027.
APA	Yu Hao,Chen DaiZhao,Wei HengYe,&Wang JianGuo.(2012).Origin of bedded chert and organic matter accumulation in the Dalong Formation of Upper Permian in western Hubei Province.ACTA PETROLOGICA SINICA,28(3),1017-1027.
MLA	Yu Hao,et al."Origin of bedded chert and organic matter accumulation in the Dalong Formation of Upper Permian in western Hubei Province".ACTA PETROLOGICA SINICA 28.3(2012):1017-1027.