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

QUATERNARY SCIENCE REVIEWS

卷:106

Review

Davies, Siwan M.¹  Abbott, Peter M.¹  Meara, Rhian H.¹  Pearce, Nicholas J. G.²  Austin, William E. N.^3,4  Chapman, Mark R.⁵  Svensson, Anders⁶  Bigler, Matthias^7,8  Rasmussen, Tine L.⁹  Rasmussen, Sune O.⁶  Farmer, Elizabeth J.⁵ 

[1] Swansea Univ, Dept Geog, Coll Sci, Swansea SA2 8PP, W Glam, Wales

[2] Aberystwyth Univ, Aberystwyth SY23 3DB, Dyfed, Wales

[3] Sch Geog & Geosci, St Andrews KY16 9AL, Fife, Scotland

[4] Scottish Marine Inst, Scottish Assoc Marine Sci, Oban PA37, Argyll, Scotland

[5] Univ E Anglia, Sch Environm Sci, Norwich NR4 7TJ, Norfolk, England

[6] Univ Copenhagen, Niels Bohr Inst, Ctr Ice & Climate, DK-2100 Copenhagen, Denmark

[7] Univ Bern, Climate & Environm Phys Phys Inst, CH-3012 Bern, Switzerland

[8] Univ Bern, Oeschger Ctr Climate Change Res, CH-3012 Bern, Switzerland

[9] Univ Tromso, Dept Geol, Ctr Arct Gas Hydrate Environm & Climate CAGE, Tromso, Norway

关键词: Tephra;    Cryptotephra;    Tephrostratigraphy;    Greenland ice-cores;    North Atlantic marine cores;    Iceland;    Tephra correlations;    Glass-shard analysis;    Rapid climate changes;   

DOI  :  10.1016/j.quascirev.2014.03.024

来源: Elsevier

【 摘 要 】

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. (C) 2014 The Authors. Published by Elsevier Ltd.

【 授权许可】

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