A late-Middle Pleistocene (Marine Isotope Stage 6) vegetated surface buried by Old Crow tephra at the Palisades, interior Alaska

A.V. Reyes, B.J.L. Jensen, G.D. Zazula, T.A. Ager, S. Kuzmina, C. La Farge, D.G. Froese

    Research output: Contribution to journalArticle

    29 Citations (Scopus)

    Abstract

    A 40 cm thick primary bed of Old Crow tephra (131 ± 11 ka), an important stratigraphic marker in eastern Beringia, directly overlies a vegetated surface at Palisades West, on the Yukon River in central Alaska. Analyses of insect, bryophyte, and vascular plant macrofossils from the buried surface and underlying organic-rich silt suggest the local presence of an aquatic environment and mesic shrub-tundra at the time of tephra deposition. Autochthonous plant and insect macrofossils from peat directly overlying Old Crow tephra suggest similar aquatic habitats and hydric to mesic tundra environments, though pollen counts indicate a substantial herbaceous component to the regional tundra vegetation. Trace amounts of arboreal pollen in sediments associated with the tephra probably reflect reworking from older deposits, rather than the local presence of trees. The revised glass fission-track age for Old Crow tephra places its deposition closer to the time of the last interglaciation than earlier age determinations, but stratigraphy and paleoecology of sites with Old Crow tephra indicate a late Marine Isotope Stage 6 age. Regional permafrost degradation and associated thaw slumping are responsible for the close stratigraphic and paleoecological relations between Old Crow tephra and last interglacial deposits at some sites in eastern Beringia.
    Original languageEnglish
    Pages (from-to)801-811
    Number of pages11
    JournalQuaternary Science Reviews
    Volume29
    Issue number5-6
    DOIs
    Publication statusPublished - 01 Mar 2010

    Bibliographical note

    Copyright 2010 Elsevier B.V., All rights reserved.

    ASJC Scopus subject areas

    • Ecology, Evolution, Behavior and Systematics
    • Geology
    • Global and Planetary Change

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