globalchange  > 影响、适应和脆弱性
DOI: 10.1016/j.epsl.2017.10.006
Scopus记录号: 2-s2.0-85034226154
论文题名:
Nitrogen cycle dynamics in the Late Cretaceous Greenhouse
作者: Junium C.K.; Meyers S.R.; Arthur M.A.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 481
起始页码: 404
结束页码: 411
语种: 英语
英文关键词: anoxia ; astronomical time scale ; black shales ; intertropical convergence zone ; nitrogen cycling ; TEX86
Scopus关键词: Greenhouses ; Isotopes ; Oil shale ; Shale ; Site selection ; anoxia ; Astronomical time scale ; Black shales ; Intertropical convergence zone ; Nitrogen cycling ; TEX86 ; Nitrogen ; anoxia ; black shale ; Cretaceous ; greenhouse gas ; intertropical convergence zone ; nitrogen cycle ; nitrogen isotope ; paleoenvironment ; timescale ; Atlantic Ocean ; Demerara Rise
英文摘要: Great attention has been paid to the origin of anomalously low nitrogen isotope values during the Late Cretaceous. Nitrogen isotope values are often as low as −3‰ and are typically less than +2‰, even in relatively organic matter-lean sediments. Here we evaluate nitrogen isotope variability during a relatively quiescent phase of the Late Cretaceous Greenhouse, between Oceanic Anoxic Events 2 and 3, using the black shales of Demerara Rise (DR). Selection of this site allows us to isolate some of the factors that control nitrogen cycle dynamics and contribute to low nitrogen isotope values. New N-isotope measurements from ODP Site 1259 reveal δ15N values that range from +0.2‰ to −3.5‰ and oscillate by 1.5‰ to 3‰ over 1.6 million years (Ma). Temporal calibration of our data using a new astronomical time scale reveals a strong ∼100 thousand year (ka) eccentricity cyclicity in δ15N. We attribute this cyclicity to oscillations in the position of the intertropical convergence zone (ITCZ) over DR that modulate upwelling intensity, chemocline depth and the degree of 15N-depletion. We also recognize a statistically significant correlation (p=0.0022) between the TEX86 indices and δ15N, with the lowest δ15N corresponding to the highest TEX86 indices. This relationship suggests that the activity and ecology of ammonia oxidizing Thaumarchaeota and the δ15N of dissolved inorganic nitrogen utilized by primary producers are linked. We therefore interpret the observed variability in the δ15N data and TEX86 indices as primarily reflecting fluctuation of upwelling intensity and chemocline depth, and the significant inverse relationship between these data sets suggests that caution should be exercised when interpreting the TEX86 in terms of temperature in similar paleoenvironmental settings. © 2017 Elsevier B.V.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110187
Appears in Collections:影响、适应和脆弱性
气候变化事实与影响

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作者单位: Department of Earth Sciences, Syracuse University, Syracuse, NY 13244, United States; Department of Geoscience, University of Wisconsin, Madison, WI 53706, United States; Department of Geosciences, Pennsylvania State University, University ParkPA 16802, United States

Recommended Citation:
Junium C.K.,Meyers S.R.,Arthur M.A.. Nitrogen cycle dynamics in the Late Cretaceous Greenhouse[J]. Earth and Planetary Science Letters,2018-01-01,481
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