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dc.contributor.authorKoehler, Matthew C.
dc.contributor.authorStüeken, Eva E.
dc.contributor.authorHillier, Stephen
dc.contributor.authorPrave, Tony
dc.identifier.citationKoehler , M C , Stüeken , E E , Hillier , S & Prave , T 2019 , ' Limitation of fixed nitrogen and deepening of the carbonate-compensation depth through the Hirnantian at Dob's Linn, Scotland ' , Palaeogeography, Palaeoclimatology, Palaeoecology , vol. 534 , 109321 .
dc.identifier.otherPURE: 260662750
dc.identifier.otherPURE UUID: 092d8b71-c837-424c-bc5d-9c145c36c965
dc.identifier.otherRIS: urn:DE6EB4D568BCE78B0E8E78B90F334AD5
dc.identifier.otherScopus: 85070873135
dc.identifier.otherORCID: /0000-0002-4614-3774/work/64033701
dc.identifier.otherORCID: /0000-0001-6861-2490/work/65014414
dc.identifier.otherWOS: 000504504200018
dc.descriptionThis study was funded by University of Washington Department of Earth and Space Sciences Harry Wheeler Scholarship and Jody Bourgeois Graduate Student Support Fund granted to MCK. Stephen Hillier acknowledges support of the Scottish Government's Rural and Environment Science and Analytical Services Division (RESAS).en
dc.description.abstractThe 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.
dc.relation.ispartofPalaeogeography, Palaeoclimatology, Palaeoecologyen
dc.rightsCopyright © 2019 Elsevier B.V. All rights reserved. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at
dc.subjectNitrogen isotopesen
dc.subjectPaleozoic nitrogen cyclingen
dc.subjectAbiogenic carbonate storageen
dc.subjectAmmonium migrationen
dc.subjectNitrogen in clayen
dc.subjectGE Environmental Sciencesen
dc.subjectSDG 13 - Climate Actionen
dc.subjectSDG 14 - Life Below Wateren
dc.titleLimitation of fixed nitrogen and deepening of the carbonate-compensation depth through the Hirnantian at Dob's Linn, Scotlanden
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews. School of Earth & Environmental Sciencesen
dc.contributor.institutionUniversity of St Andrews. St Andrews Centre for Exoplanet Scienceen
dc.contributor.institutionUniversity of St Andrews. Scottish Oceans Instituteen
dc.contributor.institutionUniversity of St Andrews. St Andrews Sustainability Instituteen
dc.contributor.institutionUniversity of St Andrews. St Andrews Isotope Geochemistryen
dc.contributor.institutionUniversity of St Andrews. Marine Alliance for Science & Technology Scotlanden
dc.description.statusPeer revieweden

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