气候变化领域集成服务门户(CCPortal): Limitation of fixed nitrogen and deepening of the carbonate-compensation depth through the Hirnantian at Dob's Linn; Scotland

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DOI	10.1016/j.palaeo.2019.109321
	Limitation of fixed nitrogen and deepening of the carbonate-compensation depth through the Hirnantian at Dob's Linn; Scotland
	Koehler M.C.; Stüeken E.E.; Hillier S.; Prave A.R.
发表日期	2019
ISSN	0031-0182
卷号	534
英文摘要	The late Ordovician is characterized by dramatic changes in global climate concurrent with a major mass extinction and possible changes in ocean redox. To further refine our understanding of these events, we present nitrogen and carbon isotope and abundance data from the Ordovician-Silurian (O-S) Global Boundary Stratotype Section and Point at Dob's Linn, Scotland. We show that this section experienced post-depositional ammonium migration from the organic-rich to the organic-poor horizons. However, our data suggest that isotopic fractionations from ammonium substitution into illitic clay minerals are small and can be corrected. Reconstructed primary nitrogen isotope ratios indicate that unlike in tropical continental shelf sections that were transiently enriched in nitrate during the Hirnantian glaciation, the sub-tropical continental slope setting at Dob's Linn experienced persistent limitation of fixed nitrogen across the O-S boundary. Shallow subpolar settings appear to be the only environment that shows persistent nitrate availability at that time. This pattern suggests that spatial trends in marine nitrate concentrations – which are observed in the modern ocean as a result of latitudinal temperature gradients – were already established during the Paleozoic. While the average marine O2 chemocline depth may have deepened during the Hirnantian glaciation, it probably did not lead to global ventilation of the deep ocean, which may have been delayed until the Carboniferous. Furthermore, carbonate data from this and other sections suggest a deepening of the carbonate compensation depth (CCD) during the Hirnantian. This observation indicates that Pacific-style responses of the CCD to glacial/interglacial periods were operational across the O-S boundary, and that the expansion of abiotic carbonate deposition and preservation beyond the shelf break could have in-part mediated changes to surface CO2 during these extreme changes in climate. © 2019 Elsevier B.V.
英文关键词	Abiogenic carbonate storage; Ammonium migration; Nitrogen in clay; Nitrogen isotopes; Paleozoic nitrogen cycling
语种	英语
scopus关键词	ammonium; carbon isotope; carbonate; Carboniferous; concentration (composition); continental shelf; continental slope; glaciation; global climate; Hirnantian; isotopic fractionation; mass extinction; nitrogen cycle; nitrogen fixation; nitrogen isotope; Paleozoic; shelf break; subtropical region; Scotland; United Kingdom
来源期刊	Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/150795
作者单位	Department of Earth & Space Sciences and Astrobiology Program, University of Washington, Seattle, WA 98195-1310, United States; School of Earth and Environmental Sciences, University of St. Andrews, St. Andrews, KY16 9AL, United Kingdom; The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, United Kingdom; Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, Uppsala, SE-75007, Sweden
推荐引用方式 GB/T 7714	Koehler M.C.,Stüeken E.E.,Hillier S.,et al. Limitation of fixed nitrogen and deepening of the carbonate-compensation depth through the Hirnantian at Dob's Linn; Scotland[J],2019,534.
APA	Koehler M.C.,Stüeken E.E.,Hillier S.,&Prave A.R..(2019).Limitation of fixed nitrogen and deepening of the carbonate-compensation depth through the Hirnantian at Dob's Linn; Scotland.Palaeogeography, Palaeoclimatology, Palaeoecology,534.
MLA	Koehler M.C.,et al."Limitation of fixed nitrogen and deepening of the carbonate-compensation depth through the Hirnantian at Dob's Linn; Scotland".Palaeogeography, Palaeoclimatology, Palaeoecology 534(2019).