Late Quaternary tephrostratigraphy, Ahklun Mountains, SW Alaska

摘要: Radiocarbon-dated sediment cores from six lakes in the Ahklun Mountains, south-western Alaska, were used to interpolate ages of late Quaternary tephra beds ranging age 25.4 0.4 ka. The are located downwind Aleutian Arc and Alaska Peninsula volcanoes northern Bristol Bay area between 159° 161°W at around 60°N. Sedimentation-rate models for each lake based on a published spline-fit procedure that uses Monte Carlo simulation determine model uncertainty. In all, 62 14C construct models, including 23 presented here first time. Lone Spruce Pond is 18 ages, currently best-resolved Holocene available region, with an average 2σ uncertainty about ± 109 years over past 14.5 ka. sedimentary sequence contains seven beds, more than previously found any other area. Of 26 radiocarbon-dated soil pit, correlated two or sites their ages. major-element geochemistry glass shards most these supports age-based correlations. remaining appear be present only one site unique age. 5.8 ka similar widespread Aniakchak [3.7 ± 0.2 (1σ) ka], but can distinguished conclusively its trace-element geochemistry. 3.1 0.4 ka tephras have major- geochemical compositions indistinguishable prominent tephra, might represent redeposited beds. Only all lakes: (3.7 ± 0.2 ka) Tephra B (6.1 ± 0.3 ka). as chronostratigraphic markers sequences Cascade Sunday lakes, which undated analyzed this study correlate new regional tephrostratigraphy. Copyright © 2012 John Wiley & Sons, Ltd.