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Tephra in deglacial ocean sediments south of Iceland: Stratigraphy, geochemistry and oceanic reservoir ages

Thornalley, DJR; McCave, IN; Elderfield, H; (2011) Tephra in deglacial ocean sediments south of Iceland: Stratigraphy, geochemistry and oceanic reservoir ages. Journal of Quaternary Science , 26 (2) 190 - 198. 10.1002/jqs.1442. Green open access

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Abstract

Icelandic tephra layers within deglacial ocean sediment cores from south of Iceland have been detected and their timing with respect to the climate shifts of the last deglaciation constrained. Geochemical analysis of the tephra allowed the likely source volcanic systems to be identified. The previously known Saksunarvatn ash and Vedde ash are recognised and described. Several other major tephra layers are examined: basaltic eruption(s) of Katla at ∼8.4 ka; a basaltic eruption of Katla at ∼12.6 ka; a rhyolitic eruption of Katla at ∼13.6 ka producing tephra similar in appearance and composition to the Vedde ash; a basaltic eruption of Katla at ∼14.0 ka; and two basaltic eruptions of Grímsvötn at ∼14.6 ka and ∼15.0 ka. Abundant rhyolitic ash with a similar appearance and chemistry to the Vedde ash is found throughout the deglacial interval, predating the Vedde ash by up to 3000 years, supporting previous suggestions that there were pre-Vedde ash eruptions of rhyolite that may have contributed to North Atlantic Ash Zone 1. / This study expands the tephro-stratigraphic framework of the North Atlantic and provides a marine archive in which the timing of tephra layers (useful as isochrons) can be directly compared to major ocean and climate events of the last deglaciation. Furthermore, by correlating tephra layers and abundance changes in the polar foraminifera, Neogloboquadrina pachyderma (sinistral), to equivalent tephra events and inferred abrupt cooling/warming in Greenland ice-cores, contemporaneous 14C-dated planktonic foraminifera have been used to estimate changes in the surface radiocarbon reservoir age south of Iceland. Consistent with previous studies, larger surface reservoir ages are calculated during late Heinrich Stadial 1 and the Younger Dryas (∼2000 years and ∼800–1900 years respectively).

Type: Article
Title: Tephra in deglacial ocean sediments south of Iceland: Stratigraphy, geochemistry and oceanic reservoir ages
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/jqs.1442
Publisher version: http://dx.doi.org/10.1002/jqs.1442
Language: English
Additional information: This is the peer reviewed version of the following article: Thornalley, DJR; McCave, IN; Elderfield, H; (2011) Tephra in deglacial ocean sediments south of Iceland: Stratigraphy, geochemistry and oceanic reservoir ages. Journal of Quaternary Science, 26 (2) 190 - 198., which has been published in final form at http://dx.doi.org/10.1002/jqs.1442. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving (http://olabout.wiley.com/WileyCDA/Section/id-820227.html).
Keywords: tephrochronology; paleoceanography; North Atlantic; climatology; deglacial
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL SLASH
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Geography
URI: https://discovery.ucl.ac.uk/id/eprint/1396382
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