Tracing marine cryptotephras in the North Atlantic during the Last Glacial Period: Improving the North Atlantic marine tephra framework

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Authors

Peter Abbott , Adam Griggs, Anna Bourne, Mark Chapman, Siwan Davies

Abstract

Tephrochronology is increasingly being recognised as a key tool for the correlation of disparate palaeoclimatic archives, underpinning chronological models and facilitating climatically independent comparisons of climate proxies. Tephra frameworks integrating both distal and proximal tephra occurrences are essential to these investigations providing key information on their spatial distributions, geochemical signatures, eruptive sources as well as any available chronological and/or stratigraphic information. Frameworks also help to avoid mis-correlation of horizons and provide important information on volcanic history. Here we present a comprehensive framework of 14 tephra horizons from North Atlantic marine sequences spanning 25-60 ka BP. Horizons previously discovered as visible or coarse-grained deposits have been combined with 11 newly recognised volcanic events, identified through the application of cryptotephra identification and characterisation methods to a wide network of marine sequences. Their isochronous integrity has been assessed using their physical characteristics. All horizons originated from Iceland with the vast majority having a basaltic composition sourced from the Grímsvötn, Kverkfjöll, Hekla/Vatnafjöll and Katla volcanicsystems. New occurrences, improved stratigraphic placements and a refinement of the geochemical signature of the NAAZ II are reported and the range of the FMAZ IV has been extended. In addition, several significant geochemical populations that further investigations could show to be isochronous are reported. This tephra framework provides the foundation for the correlation and synchronisation of these marine records to the Greenland ice-cores and European terrestrial records to investigate the phasing, rate, timing and mechanisms controlling the rapid climate changes that characterised the last glacial period.

DOI

https://doi.org/10.31223/osf.io/4vm7p

Subjects

Earth Sciences, Other Earth Sciences, Physical Sciences and Mathematics

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Dates

Published: 2018-12-12 16:33

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CC BY Attribution 4.0 International

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