Origin of last-glacial loess in the western Yukon-Tanana Upland, central Alaska, USA

Quaternary Research
By: , and 

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Abstract

Loess is widespread over Alaska, and its accumulation has traditionally been associated with glacial periods. Surprisingly, loess deposits securely dated to the last glacial period are rare in Alaska, and paleowind reconstructions for this time period are limited to inferences from dune orientations. We report a rare occurrence of loess deposits dating to the last glacial period, ~19 ka to ~12 ka, in the Yukon-Tanana Upland. Loess in this area is very coarse grained (abundant coarse silt), with decreases in particle size moving south of the Yukon River, implying that the drainage basin of this river was the main source. Geochemical data show, however, that the Tanana River valley to the south is also a likely distal source. The occurrence of last-glacial loess with sources to both the south and north is explained by both regional, synoptic-scale winds from the northeast and opposing katabatic winds that could have developed from expanded glaciers in both the Brooks Range to the north and the Alaska Range to the south. Based on a comparison with recent climate modeling for the last glacial period, seasonality of dust transport may also have played a role in bringing about contributions from both northern and southern sources.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Origin of last-glacial loess in the western Yukon-Tanana Upland, central Alaska, USA
Series title Quaternary Research
DOI 10.1017/qua.2018.11
Volume 89
Issue 3
Year Published 2018
Language English
Publisher Cambridge University Press
Contributing office(s) Geosciences and Environmental Change Science Center
Description 23 p.
First page 797
Last page 819
Country United States
State Alaska