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Marine 187Os/188Os isotope stratigraphy reveals the interaction of volcanism and ocean circulation during Oceanic Anoxic Event 2.

Du Vivier, A.D.C. and Selby, D. and Sageman, B.B and Jarvis, I. and Gröcke, D.R. and Voigt, S. (2014) 'Marine 187Os/188Os isotope stratigraphy reveals the interaction of volcanism and ocean circulation during Oceanic Anoxic Event 2.', Earth and planetary science letters., 389 (1). pp. 23-33.

Abstract

High-resolution osmium (Os) isotope stratigraphy across the Cenomanian–Turonian Boundary Interval from 6 sections for four transcontinental settings has produced a record of seawater chemistry that demonstrates regional variability as a function of terrestrial and hydrothermal inputs, revealing the impact of palaeoenvironmental processes. In every section the 187Os/188Os profiles show a comparable trend; radiogenic values in the lead up to Oceanic Anoxic Event 2 (OAE 2); an abrupt unradiogenic trend at the onset of OAE 2; an unradiogenic interval during the first part of OAE 2; and a return to radiogenic values towards the end of the event, above the Cenomanian–Turonian boundary. The unradiogenic trend in 187Os/188Os is synchronous in all sections. Previous work suggests that activity of the Caribbean LIP (Large Igneous Province) was the source of unradiogenic Os across the OAE 2 and possibly an instigator of anoxia in the oceans. Here we assess this hypothesis and consider the influence of activity from other LIPs; such as the High Arctic LIP. A brief shift to high radiogenic 187Os/188Os values occurred in the Western Interior Seaway before the onset of OAE 2. We evaluate this trend and suggest that a combination of factors collectively played critical roles in the initiation of OAE 2; differential input of nutrients from continental and volcanogenic sources, coupled with efficient palaeocirculation of the global ocean and epeiric seas, enhanced productivity due to higher nutrient availability, which permitted penecontemporaneous transport of continental and LIP-derived nutrients to trans-equatorial basins.

Item Type:Article
Keywords:OAE 2, 187Os/188Os isotope composition, Palaeocirculation, Global warming, Caribbean LIP, Carbon.
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Available under License - Creative Commons Attribution.
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Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1016/j.epsl.2013.12.024
Publisher statement:© 2013 The Authors. Published by Elsevier B.V. This is an open access article under the CC-BY license (http://creativecommons.org/licenses/by/3.0/).
Date accepted:17 December 2013
Date deposited:17 February 2014
Date of first online publication:06 January 2014
Date first made open access:No date available

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