A North Atlantic tephrostratigraphical framework for 130–60 ka b2k: new tephra discoveries, marine-based correlations, and future challenges

Building chronological frameworks for proxy sequences spanning 130–60 ka b2k is plagued by difficulties and uncertainties. Recent developments in the North Atlantic region, however, affirm the potential offered by tephrochronology and specifically the search for cryptotephra. Here we review the pote...

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Bibliographic Details
Published in:Quaternary science reviews 2014-12, Vol.106, p.101-121
Main Authors: Davies, Siwan M., Abbott, Peter M., Meara, Rhian H., Pearce, Nicholas J.G., Austin, William E.N., Chapman, Mark R., Svensson, Anders, Bigler, Matthias, Rasmussen, Tine L., Rasmussen, Sune O., Farmer, Elizabeth J.
Format: Article
Language:English
Subjects:
Cryptotephra
Glass-shard analysis
Greenland ice-cores
Iceland
North Atlantic marine cores
Rapid climate changes
Tephra
Tephra correlations
Tephrostratigraphy
VDP
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Summary:Building chronological frameworks for proxy sequences spanning 130–60 ka b2k is plagued by difficulties and uncertainties. Recent developments in the North Atlantic region, however, affirm the potential offered by tephrochronology and specifically the search for cryptotephra. Here we review the potential offered by tephrostratigraphy for sequences spanning 130–60 ka b2k. We combine newly identified cryptotephra deposits from the NGRIP ice-core and a marine core from the Iceland Basin with previously published data from the ice and marine realms to construct the first tephrostratigraphical framework for this time-interval. Forty-three tephra or cryptotephra deposits are incorporated into this framework; twenty three tephra deposits are found in the Greenland ice-cores, including nine new NGRIP tephras, and twenty separate deposits are preserved in various North Atlantic marine sequences. Major, minor and trace element results are presented for the new NGRIP horizons together with age estimates based on their position within the ice-core record. Basaltic tephras of Icelandic origin dominate the framework with only eight tephras of rhyolitic composition found. New results from marine core MD99-2253 also illustrate some of the complexities and challenges of assessing the depositional integrity of marine cryptotephra deposits. Tephra-based correlations in the marine environment provide independent tie-points for this time-interval and highlight the potential of widening the application of tephrochronology. Further investigations, however, are required, that combine robust geochemical fingerprinting and a rigorous assessment of tephra depositional processes, in order to trace coeval events between the two depositional realms. •A record of Icelandic tephra deposits in ice and marine cores between 60 and 130 ka.•New, previously unknown tephra deposits are identified as cryptotephras.•Marine-based cryptotephras require assessment of depositional processes.•Three tephras used to independently correlate North Atlantic marine cores.•New insights into potential of tephrochronology beyond 60 ka.
ISSN:0277-3791
1873-457X
DOI:10.1016/j.quascirev.2014.03.024