Tephra analysis in ombrotrophic peatlands: A geochemical comparison of acid digestion and density separation techniques

Roland, T.P.; Mackay, H.; Hughes, P.D.M.

Abstract

Ombrotrophic peatlands often lack any substantial local mineral component and therefore present exceptional opportunities for the extraction and identification of tephra horizons. Following concerns of shard geochemistry alteration during isolation using acid digestion, an alternative methodology using heavy liquids has been proposed. However, harsh basic and acidic digestions are rarely required in organic-rich, ombrotrophic peatlands. Consequently, this study tested for geochemical differences between tephra shards from a known rhyolitic eruption, isolated from the same stratigraphic depth of a peat sequence using density separation and an acid digestion methodology typically applied to ombrotrophic peat samples and analysed using electron probe microanalysis. Findings suggest that the two samples could not be geochemically distinguished using visual and statistical methods and that, in the context of rhyolitic tephras in ombrotrophic peats, acid digestion can be used without significant effects on the interpretation of results. Density separation may still be required in peatlands with high mineral input and further work is required to examine the effect of the acid digestion technique on tephra of non-rhyolitic compositions.

Citation

Roland, T., Mackay, H., & Hughes, P. (2015). Tephra analysis in ombrotrophic peatlands: A geochemical comparison of acid digestion and density separation techniques. Journal of Quaternary Science, 30(1), 3-8. https://doi.org/10.1002/jqs.2754

• Journal Article Type: Article
• Acceptance Date: Nov 4, 2014
• Online Publication Date: Jan 19, 2015
• Publication Date: Jan 19, 2015
• Deposit Date: Oct 29, 2020
• Journal: Journal of Quaternary Science
• Print ISSN: 0267-8179
• Electronic ISSN: 1099-1417
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 30
• Issue: 1
• Pages: 3-8
• DOI: https://doi.org/10.1002/jqs.2754
• Public URL: https://durham-repository.worktribe.com/output/1258367