Tephrochronology of last termination sequences in Europe: a protocol for improved analytical precision and robust correlation procedures (a joint SCOTAV–INTIMATE proposal)

Abstract

The precise sequence of events during the Last Termination (18 000-9000 ka 14 C yr BP), and the extent to which major environmental changes were synchronous, are difficult to establish using the radiocarbon method alone because of serious distortions of the radiocarbon time-scale, as well as the influences of site-specific errors that can affect the materials dated. Attention has therefore turned to other methods that can provide independent tests of the chronology and correlation of events during the Last Termination. With emphasis on European sequences, we summarise here the potential of tephrostratigraphy and tephrochronology to fulfil this role. Recent advances in the detection and analysis of 'hidden' tephra layers (cryptotephra) indicate that some tephras of Last Termination age are much more widespread in Europe than appreciated hitherto, and a number of new tephra deposits have also been identified. There is much potential for developing an integrated tephrochronological framework for Europe, which can help to underpin the overall chronology of events during the Last Termination. For that potential to be realised, however, there needs to be a more systematic and robust analysis of tephra layers than has been the practice in the past. We propose a protocol for improving analytical and reporting procedures, as well as the establishment of a centralised data base of the results, which will provide an important geochronological tool to support a diverse range of stratigraphical studies, including opportunities to reassess volcanic hazards. Although aimed primarily at Europe, the protocol proposed here is of equal relevance to other regions and periods of interest.

Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

“…There have been considerable advances in the methods used to detect, date and characterise volcaniclastic deposits in the last few decades (Froggatt, 1992;Turney et al, 2004;Blockley et al, 2005;Gehrels et al, 2008;Manville et al 2009;Lowe, 2011). However, subjective elements in the criteria used to identify a tephra layer deposited from an explosive volcanic eruption still remain.…”

“…'Cryptotephra' are tephra deposits that are not visible to the naked eye. They are often present as concentrations of glass shards or crystal fragments mixed with non-volcanic clasts (Lowe and Hunt, 2001;Turney et al, 2004).…”

The chronology of abrupt climate change and Late Upper Palaeolithic human adaptation in Europe

“…Indeed, members of the INTIMATE project have gone as far as to suggest that tephrochronology might provide a more robust framework for the chronology and correlation of Lateglacial sequences and events, for much of Europe (e.g. Lowe et al, 2001;Turney et al, 2004). Tephra layers provide an independent basis for testing age models based on radiocarbon dating and, because some Lateglacial tephras have been detected in Greenland ice-core records, they also potentially provide a basis for direct correlation between ice-core, marine and terrestrial records.…”

Marine tephrochronology: a personal perspective

“…These methods included the innovative use of the electron microprobe, developed mainly through the 1970s and 1980s, to obtain major element compositions of individual glass shards rather than bulk samples (Smith & Westgate 1968;Froggatt 1983Froggatt , 1992Hunt & Hill 1996).Its advent in 1968 a stroke of brilliance, the microprobe method for glass analysis, initially criticised by some 'traditional' volcanic petrologists and geo-analysts, has been widely adopted today as the cornerstone analytical technique in tephra studies used alongside stratigraphic, chronological, and mineralogical data to help enable correlations to be made (Froese et al 2008a;Lowe 2011). More recent refinements of the electron microprobe method for the analysis of glass shards or melt inclusions, or for crystals, include those described by Turney et al (2004), Kuehn et al (2011), Matsu'ura et al (2011, 2012, Hayward (2012), Hall & Hayward (2014), Marcaida et al (2014), and.…”