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

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Building chronological frameworks for proxy sequences spanning 130e60 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 130e60 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
Original languageEnglish
JournalQuaternary Science Reviews
Pages (from-to)101-121
Number of pages21
Publication statusPublished - 15 Dec 2014

ID: 120078523