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Full-glacial paleosols in perennially frozen loess sequences, Klondike goldfields, Yukon Territory, Canada |
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| Authors: | Paul T Sanborn CA Scott Smith Grant D Zazula |
| Institution: | a Ecosystem Science and Management Program, University of Northern British Columbia, 3333 University Way, Prince George, BC, Canada V2N 4Z9 b Agriculture and Agri-Food Canada, PARC Summerland, 4200 Hwy 97, Summerland, BC, Canada V0H 1Z0 c Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E1 d Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6 e Department of Geology, University of Toronto, Toronto, ON, Canada M5S 3B1 |
| Abstract: | Perennially frozen loess deposits in the Klondike goldfields include paleosols formed in full-glacial environments, correlated by Alaskan distal tephra with Marine Isotope Stages (MIS) 2 and 4. Patterns of organic and inorganic carbon and clay distribution, microstructures, and profile morphologies indicate that soil formation occurred in a base-rich environment in which organic matter accreted predominantly as root detritus. At sites approximately 20 km apart, the expression of cryoturbation and ice wedge development decreases in strength upward in loess-paleosol sequences correlated with MIS 4, suggesting increasing aridity. Configurations of cryoturbation features and ice-wedge thaw unconformities, the presence of numerous ground squirrel burrows, and an absence of peat accumulation suggest that these substrates were predominantly well-drained, with active layers of equal or greater thickness than in modern soils on similar sites in the west-central Yukon. Some characteristics of these paleosols are similar to those of modern steppe and tundra soils, consistent with plant macrofossil evidence for local ecological diversity during full-glacial conditions in eastern Beringia. |
| Keywords: | Beringia Cryoturbation Loess Paleosols Permafrost Soil micromorphology Steppe Tephra Tundra |
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