Modeled tephra ages from lake sediments, base of Redoubt Volcano, Alaska
Quaternary Geochronology
By: C.J. Schiff, D. S. Kaufman, K.L. Wallace, A. Werner, T.-L. Ku, and T. A. Brown
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Abstract
A 5.6-m-long lake sediment core from Bear Lake, Alaska, located 22 km southeast of Redoubt Volcano, contains 67 tephra layers deposited over the last 8750 cal yr, comprising 15% of the total thickness of recovered sediment. Using 12 AMS 14C ages, along with the 137Cs and 210Pb activities of recent sediment, we evaluated different models to determine the age-depth relation of the core, and to determine the age of each tephra deposit. The selected age model is based on a mixed-effect regression that was passed through the adjusted tephra-free depth of each dated layer. The estimated age uncertainty of the 67 tephras averages ??105 yr (95% confidence intervals). Tephra-fall frequency at Bear Lake was among the highest during the past 500 yr, with eight tephras deposited compared to an average of 3.7/500 yr over the last 8500 yr. Other periods of increased tephra fall occurred 2500-3500, 4500-5000, and 7000-7500 cal yr. Our record suggests that Bear Lake experienced extended periods (1000-2000 yr) of increased tephra fall separated by shorter periods (500-1000 yr) of apparent quiescence. The Bear Lake sediment core affords the most comprehensive tephrochronology from the base of the Redoubt Volcano to date, with an average tephra-fall frequency of one every 130 yr. ?? 2007 Elsevier Ltd. All rights reserved.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Modeled tephra ages from lake sediments, base of Redoubt Volcano, Alaska |
| Series title | Quaternary Geochronology |
| DOI | 10.1016/j.quageo.2007.05.001 |
| Volume | 3 |
| Issue | 1-2 |
| Year Published | 2008 |
| Language | English |
| Contributing office(s) | Volcano Hazards Program |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Quaternary Geochronology |
| First page | 56 |
| Last page | 67 |
| Google Analytic Metrics | Metrics page |