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Jensen, B.J.L., 2007

Tephrochronology of middle to late Pleistocene loess in east-central Alaska

Bibliographic Reference

Jensen, B.J.L., 2007, Tephrochronology of middle to late Pleistocene loess in east-central Alaska: Edmonton, Alberta, Canada, University of Alberta, M.S. thesis, 237 p.


Chester Bluff, in east-central Alaska, is a middle to late Pleistocene loess record with interbedded tephra. Old Crow tephra (~140 ka) and VT tephra (~80 ka), two regional stratigraphic markers, GI tephra (~560 ka) of Fairbanks and Preido Hill tephra of the Klondike are found at Chester Bluff. Presence of these beds will aid in correlating disparate paleoenvironmental records across eastern Beringia. There are 15 new beds, 12 from the Wrangell volcanic field and/or Hayes volcano, one from the Aleutian-Arc/Alaska Peninsula and three unclassified beds. Chester Bluff is normally magnetized, indicating a Bruhnes age (less than 780 ka). A minimum of two interglacials, one late-Middle Pleistocene, the other early-Middle Pleistocene, and five organic horizons representing interstadials or interglacials, are present. Collectively, sediments at Chester Bluff span most of the middle to late Pleistocene (~780 to <~80 ka). The bluffs represent the most extensive middle-to-late Pleistocene sedimentary record yet established for Yukon or Alaska.

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