Duane G. Froese^1,*, Grant D. Zazula², John A. Westgate³, Shari J. Preece³, Paul T. Sanborn⁴, Alberto V. Reyes⁵, Nicholas J.G. Pearce⁶

1 Dept. of Earth and Atmospheric Sciences, Univ. of Alberta, Edmonton, Alberta T6G 2E3
2 Yukon Palaeontology Program, Whitehorse, Yukon Territory Y1A 2C6
3 Dept. of Geology, Univ. of Toronto, Toronto, Ontario M5S 3B1
4 Ecosystem Science and Management Program, Univ. of Northern British Columbia, Prince George, British Columbia V2N 4ZN
5 Dept. of Earth and Atmospheric Sciences, Univ. of Alberta, Edmonton, Alberta T6G 2E3
6 Inst. of Geography and Earth Science, University of Wales, Aberystwyth SY23 3DB, UK

The Klondike goldfields of Yukon, Canada, contain a key record of Pleistocene Beringia, the region of Alaska, Siberia, and Yukon that remained largely unglaciated during the late Cenozoic. A concentration of mining exposures, with relict permafrost that is locally more than 700,000 years old, provides exceptional preservation of paleoenvironmental archives and a new perspective on the nature of paleoenvironments during the Pleistocene. A critical feature is the stratigraphic association of distal tephra beds with these paleoenvironmental archives, which facilitates their regional correlation and, in many cases, provides independent ages for the paleoenvironmental assemblages. Paleoenvironmental analyses of fossil arctic ground-squirrel middens and buried vegetation indicate the presence of cryoxerophilous (“steppe-tundra”) vegetation growing on well-drained substrates with deep active layers (seasonal thaw depths) during cold intervals of the Pleistocene. Studies of full-glacial paleosols and cryostratigraphic relations of associated ground ice indicate the importance of active loess deposition and surface vegetation cover in maintaining the functionally distinct mammoth-steppe biome, which supported grazing mega-fauna populations, including mammoth, horse, and bison.

Manuscript received 15 April 2009; accepted 27 May 2009.

doi: 10.1130/GSATG54A.1

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