Using cryptotephras to extend regional tephrochronologies: an example from southeast Alaska and implications for hazard assessment

Payne, Richard; Blackford, Jeffrey; van der Plicht, Johannes

Abstract

Cryptotephrochronology, the use of hidden, diminutive volcanic ash layers to date sediments, has rarely been applied outside western Europe but has the potential to improve the tephrochronology of other regions of the world. Here we present the first comprehensive cryptotephra study in Alaska. Cores were extracted from five peatland sites, with cryptotephras located by ashing and microscopy and their glass geochemistry examined using electron probe microanalysis. Glass geochemical data from nine tephras were compared between sites and with data from previous Alaskan tephra studies. One tephra present in all the cores is believed to represent a previously unidentified eruption of Mt. Churchill and is named here as the ‘Lena tephra'. A mid-Holocene tephra in one site is very similar to Aniakchak tephra and most likely represents a previously unidentified Aniakchak eruption, ca. 5300-5030cal yr BP. Other tephras are from the late Holocene White River eruption, a mid-Holocene Mt. Churchill eruption, and possibly eruptions of Redoubt and Augustine volcanoes. These results show the potential of cryptotephras to expand the geographic limits of tephrochronology and demonstrate that Mt. Churchill has been more active in the Holocene than previously appreciated. This finding may necessitate reassessment of volcanic hazards in the region.

Citation

Payne, R., Blackford, J., & van der Plicht, J. (2008). Using cryptotephras to extend regional tephrochronologies: an example from southeast Alaska and implications for hazard assessment. Quaternary Research, 69(1), 42-55. https://doi.org/10.1016/j.yqres.2007.10.007

• Journal Article Type: Article
• Online Publication Date: Jan 20, 2017
• Publication Date: 2008-01
• Deposit Date: Nov 13, 2014
• Journal: Quaternary Research
• Print ISSN: 0033-5894
• Publisher: Cambridge University Press
• Peer Reviewed: Peer Reviewed
• Volume: 69
• Issue: 1
• Pages: 42-55
• DOI: https://doi.org/10.1016/j.yqres.2007.10.007
• Keywords: Tephra; Cryptotephra; Radiocarbon; White River Ash; Mt Churchill; Aniakchak; Alaska; Holocene
• Public URL: https://hull-repository.worktribe.com/output/470861
• Publisher URL: https://www.cambridge.org/core/journals/quaternary-research/article/using-cryptotephras-to-extend-regional-tephrochronologies-an-example-from-southeast-alaska-and-implications-for-hazard-assessment/9E3371B16DDD14EEA321F38692D0A76A
• Contract Date: Nov 13, 2014