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

• Published in: Quaternary Research
• Main Authors: Blackford, J. J., Payne, R. J., Heggen, M. P., Caballero, A. de la Riva, van der Plicht, J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: Volcanic impacts; Vegetation; Carbon balance; Beringia; Acari; Radiocarbon dating; SANTORINI MINOAN ERUPTION; 17TH-CENTURY BC DATE; VOLCANIC-ERUPTIONS; ENVIRONMENTAL-IMPACT; TEPHRA DEPOSITION; ORIBATID MITES; SUPER-ERUPTION; TESTATE AMEBAS; TREE-RINGS; SMALL LAKE; Alaska
• Online Access: https://hdl.handle.net/11370/b98d7571-2808-4d8c-ad92-a5d5d7a167f3; https://research.rug.nl/en/publications/b98d7571-2808-4d8c-ad92-a5d5d7a167f3; https://doi.org/10.1016/j.yqres.2014.04.013

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. (C) 2014 University of Washington. Published by Elsevier Inc. All rights reserved.