Distal volcanic ash layers in the Lateglacial Interstadial (GI-1): problems of stratigraphic discrimination

A new Icelandic ash layer has been detected in mid-Interstadial sediments in a number of Scottish Lateglacial sequences and has been named the Penifiler Tephra. It is rhyolitic in composition and possesses a chemistry, which is similar to the Borrobol Tephra of early Lateglacial Interstadial age, wh...

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Bibliographic Details
Published in:Quaternary Science Reviews
Main Authors: Pyne-O'Donnell, S. D. F., Blockley, Simon, Turney, C. S. M., Lowe, J. J.
Format: Article in Journal/Newspaper
Language:English
Published: 2008
Subjects:
GLACIAL-INTERGLACIAL TRANSITION
ELECTRON-PROBE MICROANALYSIS
NORTH-ATLANTIC REGION
EARLY HOLOCENE
WHITRIG BOG
PALEOENVIRONMENTAL RECORD
EVENT STRATIGRAPHY
WESTERN NORWAY
INNER HEBRIDES
TEPHRA SHARDS
Faculty of Science\Geography
Research Groups and Centres\Geography\Centre for Quaternary Research
Norway
ice core
NGRIP
North Atlantic
Online Access:https://repository.royalholloway.ac.uk/items/947691c4-1ba0-40fa-da0b-6a96b7259771/5/
https://doi.org/10.1016/j.quascirev.2007.02.019
Description
Summary:A new Icelandic ash layer has been detected in mid-Interstadial sediments in a number of Scottish Lateglacial sequences and has been named the Penifiler Tephra. It is rhyolitic in composition and possesses a chemistry, which is similar to the Borrobol Tephra of early Lateglacial Interstadial age, which also occurs in a number of these same sequences. Where the Borrobol Tephra has been identified in these sequences it consistently exhibits a diffuse distribution accompanied in some cases by stratigraphic bimodality. A number of sedimentological and taphonomic factors are considered in order to account for this distribution. One possibility is that these distributions are produced by taphonomic factors. Another possibility is that the Borrobol Tephra may not be the product of a single Icelandic eruption, but of two events closely spaced in time. In at least two of the sequences investigated in this study, basaltic shards were found in association with the Penifiler and Borrobol tephras, suggesting either a basaltic phase associated with these eruptions, or coincident eruptions from a separate basaltic volcanic centre. The discovery of the new Penifiler Tephra makes a contribution to the regional tephrostratigraphic framework, and provides an additional isochron for assessing the synchroneity of palaeoenvironmental changes during the Interstadial. The true stratigraphic nature and age of the Borrobol Tephra, however, remains unresolved and, therefore. its use as an isochron is more problematic. The possible occurrence of basaltic populations may strengthen correlations with basaltic tephras recently detected in the NGRIP ice-core. (C) 2007 Elsevier Ltd. All rights reserved.

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