DOI: 10.1016/j.palaeo.2016.05.023
论文题名: Genesis of Cryogenian Datangpo manganese deposit: Hydrothermal influence and episodic post-glacial ventilation of Nanhua Basin, South China
作者: Yu W. ; Algeo T.J. ; Du Y. ; Maynard B. ; Guo H. ; Zhou Q. ; Peng T. ; Wang P. ; Yuan L.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2016
卷: 459 起始页码: 321
结束页码: 337
语种: 英语
英文关键词: Corg/P
; Marinoan glaciation
; Nd isotope
; Sr isotope
; Sturtian glaciation
; Yangtze Block
英文摘要: The Neoproterozoic Datangpo Formation of the Nanhua Basin in South China records interglacial sedimentation between the ~ 720–660-Ma Sturtian and ~ 654–635-Ma Marinoan glaciations. The lower part (1st Member) of this formation contains manganese-rich deposits that represent a mixture of two main components, Mn-carbonates and Mn-bearing aluminosilicates (clay minerals). The Mn-carbonate component is characterized by high La/Sc ratios, high initial 87Sr/86Sr ratios, and low initial εNd(t) values, and the siliciclastic component by low La/Sc ratios, low initial 87Sr/86Sr ratios, and high initial εNd(t) values. The likely source of the non-radiogenic siliciclastic material is weathering of Neoproterozoic continental flood basalts on the Yangtze Block. Discriminant plots show that the Mn-ore samples have compositions consistent with at least partial derivation from hydrothermal sources. Mn-carbonate deposition was the result of reactions between aqueous Mn and sedimentary organic matter during early diagenesis that led to elevated Mn2 + concentrations and alkalinity in sediment porewaters. Based on these observations, we propose a new metallogenic model for the Datangpo Formation manganese deposits. During the Sturtian glaciation, the anoxic Nanhua Basin accumulated abundant dissolved Mn, a substantial fraction of which was derived from hydrothermal sources. When glaciation ended and a redox-stratified water column developed in the basin with an oxic surface layer and an anoxic deep layer, the accumulated dissolved Mn precipitated as Mn-oxides on the basin floor during episodic ventilation events. After co-burial with organic-rich sediments, these Mn-oxides were reduced during organic matter oxidation, which led to the formation of secondary Mn-carbonates (rhodochrosite) through increases in sediment porewater Mn2 + and in alkalinity via microbial sulfate reduction and microbially mediated Mn reduction. © 2016 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68310
Appears in Collections: 过去全球变化的重建
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作者单位: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences-Wuhan, Wuhan, China; State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences-Wuhan, Wuhan, China; Department of Geology, University of Cincinnati, Cincinnati, OH, United States; Guizhou Bureau of Geology and Mineral Exploration and Development, Guiyang, China; Guangzhou Institute of Geochemistry, China Academy of Science, Guangzhou, China; 103 Geological Party, Guizhou Bureau of Geology and Mineral Exploration and Development, Tongren, China
Recommended Citation:
Yu W.,Algeo T.J.,Du Y.,et al. Genesis of Cryogenian Datangpo manganese deposit: Hydrothermal influence and episodic post-glacial ventilation of Nanhua Basin, South China[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2016-01-01,459