An improved proximal tephrochronology for Redoubt Volcano, Alaska

Caleb J. Schiff, Darrell S. Kaufman, Kristi L. Wallace, Michael E. Ketterer

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Sediment cores from lakes in volcanically active regions can be used to reconstruct the frequency of tephra-fall events. We studied sediment cores from two lakes within 25. km of the summit of Redoubt Volcano, western Cook Inlet, to develop a robust age model for the Holocene tephrochronology, and to assess the extent to which the tephrostratigraphies were correlative between the two nearby lakes. Visually distinct tephra layers were correlated among cores from Bear and Cub lakes, located within 17. km of each other, to construct a composite age model, which incorporates two Pu-activity profiles and 27 radiocarbon ages, and extends the record back to 11,540. cal a BP. The age model was used to interpolate the ages and quantify the uncertainties of ages for all tephras at least 1. mm thick. Between -55 and 3850. a BP, 31 tephras were deposited in Bear Lake and 41 tephras in Cub Lake. Bear Lake contains an additional 38 tephras deposited between 11,540 and 3850. a BP. During the period of overlap, (-55 to 3850. a BP), 24 tephras are of significantly different ages, including nine from Bear Lake and 17 from Cub Lake. The presence of these unique tephras indicates that ejecta plumes erupted from Redoubt Volcano can be highly directional, and that sediment cores from more than one lake are needed for a comprehensive reconstruction of tephra-fall events. Unlike distal lakes in south Alaska, where geomorphic and limnological factors dominate the quality of the tephrostratigraphic record, the variability in tephra-fall trajectory near a Redoubt Volcano appears to be a major control on the number of tephras contained in the sediment of proximal lakes.

Original languageEnglish (US)
Pages (from-to)203-214
Number of pages12
JournalJournal of Volcanology and Geothermal Research
Volume193
Issue number3-4
DOIs
StatePublished - Jun 1 2010

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Keywords

  • Alaska
  • Cook Inlet region
  • Lake sediments
  • Redoubt Volcano
  • Tephra
  • Tephrochronology
  • Tephrostratigraphy

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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