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Age and impacts of the caldera-forming Aniakchak II eruption in western Alaska

Research output: Contribution to journalArticle

Published copy (DOI)

Author(s)

  • J. J. Blackford
  • R. J. Payne
  • M. P. Heggen
  • A. de la Riva Caballero
  • J. van der Plicht

Department/unit(s)

Publication details

JournalQUATERNARY RESEARCH
DateE-pub ahead of print - 17 May 2014
DatePublished (current) - Jul 2014
Issue number1
Volume82
Number of pages11
Pages (from-to)85-95
Early online date17/05/14
Original languageEnglish

Abstract

The mid-Holocene eruption of Aniakchak volcano (Aniakchak II) in southwest Alaska was among the largest eruptions globally in the last 10,000 years (VEI-6). Despite evidence for possible impacts on global climate, the precise age of the eruption is not well-constrained and little is known about regional environmental impacts. A closely spaced sequence of radiocarbon dates at a peatland site over 1000 km from the volcano show that peat accumulation was greatly reduced with a hiatus of approximately 90–120 yr following tephra deposition. During this inferred hiatus no paleoenvironmental data are available but once vegetation returned the flora changed from a Cyperaceae-dominated assemblage to a Poaceae-dominated vegetation cover, suggesting a drier and/or more nutrient-rich ecosystem. Oribatid mites are extremely abundant in the peat at the depth of the ash, and show a longer-term, increasingly wet peat surface across the tephra layer. The radiocarbon sample immediately below the tephra gave a date of 1636–1446 cal yr BC suggesting that the eruption might be younger than previously thought. Our findings suggest that the eruption may have led to a widespread reduction in peatland carbon sequestration and that the impacts on ecosystem functioning were profound and long-lasting.

    Research areas

  • Volcanic impacts, Vegetation, Carbon balance, Beringia, Acari, Radiocarbon dating

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