DOI: 10.1016/j.palaeo.2015.10.022
论文题名: Changes in marine nitrogen fixation and denitrification rates during the end-Devonian mass extinction
作者: Liu J. ; Qie W. ; Algeo T.J. ; Yao L. ; Huang J. ; Luo G.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2016
卷: 448 起始页码: 195
结束页码: 206
语种: 英语
英文关键词: Hangenberg Event
; Late Devonian
; Mass extinction
; Nitrogen cycle
; Paleogeography
; South China
英文摘要: The end-Devonian was a critical interval in Earth history recording the transition from the Early Paleozoic greenhouse climate to the Late Paleozoic icehouse climate. A mass extinction at this time (the Hangenberg extinction) eliminated ~21% of genera and ~16% of families of marine invertebrates, although its causes remain poorly understood. The marine nitrogen cycle is intimately related to the nutrient status of seawater, microbial community composition, and the redox condition of the oceans, and, thus, it may provide insights into the mechanism(s) of the end-Devonian mass extinction and climate change. Here, we analyzed high-stratigraphic-resolution bulk-sediment nitrogen isotope variation (δ15Nbulk) in three sections from South China: (1) Long'an, an isolated carbonate platform section, (2) Qilinzhai, a shallow-water carbonate platform section between the Yangtze Oldland and the Youjiang Trough, and (3) Malanbian, a shallow-water carbonate platform section between the Yangtze and Cathaysia oldlands and distant from deep-water areas. Our δ15Nbulk records show a major perturbation to the marine nitrogen cycle in the Middle Siphonodella praesulcata Zone, which is marked by a decline in δ15Nbullk from +4‰ to 0‰ at Long'an and from +4.5‰ to +2.5‰ at Malanbian. This perturbation coincided with the main end-Devonian mass extinction as well as with a negative shift in carbonate carbon isotopes (δ13Ccarb). The shift to lower δ15N values suggests locally enhanced nitrogen fixation, possibly as a consequence of increased denitrification in response to globally expanded marine anoxia. Thus, these δ15Nbulk data are consistent with the hypothesis that intense anoxia was the immediate cause of the end-Devonian mass extinction. The δ15Nbulk records generated in this study suggest that there was significant spatial and temporal variation in the nitrogen isotope composition of seawater nitrate in the Yangtze marginal sea during the latest Devonian. This variation may have been related to the complex paleogeography of the South China Craton, which contained numerous isolated and continent-attached platforms and deep-water basins that influenced watermass circulation, nutrient inventories and primary productivity levels, and watermass ventilation and redox conditions. © 2015 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68526
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 and School of Earth Sciences, China University of Geosciences, Wuhan, China; Key Laboratory of Economic Stratigraphy and Paleogeography, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing, China; State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, China; Department of Geology, University of Cincinnati, Cincinnati, OH, United States
Recommended Citation:
Liu J.,Qie W.,Algeo T.J.,et al. Changes in marine nitrogen fixation and denitrification rates during the end-Devonian mass extinction[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2016-01-01,448