Aeolian stratigraphy describes ice-age paleoenvironments in unglaciated Arctic Alaska

QUATERNARY SCIENCE REVIEWS

卷:182

Article

Gaglioti, Benjamin V.¹  Mann, Daniel H.²  Groves, Pamela³  Kunz, Michael L.⁴  Farquharson, Louise M.²  Reanier, Richard E.⁵  Jones, Benjamin M.⁶  Wooller, Matthew J.^7,8 

[1] Columbia Univ, Lamont Doherty Earth Observ, 61 Route 9w, Palisades, NY 10964 USA

[2] Univ Alaska Fairbanks, Dept Geosci, 900 Yukon Dr, Fairbanks, AK 99775 USA

[3] Univ Alaska Fairbanks, Inst Arctic Biol, 902 North Koyukuk Dr, Fairbanks, AK 99775 USA

[4] Univ Alaska Fairbanks, Sch Nat Resources & Extens, POB 757140, Fairbanks, AK 99775 USA

[5] Reanier & Associates Inc, 1215 SW 170th St, Seattle, WA 98166 USA

[6] US Geol Survey, Alaska Sci Ctr, 4210 Univ Dr, Anchorage, AK 99508 USA

[7] Univ Alaska Fairbanks, Water & Environm Res Ctr, 306 Tanana Dr, Fairbanks, AK 99775 USA

[8] Univ Alaska Fairbanks, Sch Fisheries & Ocean Sci, 306 Tanana Dr, Fairbanks, AK 99775 USA

关键词: Ice age;    Arctic;    Alaska;    North slope;    Pleistocene;    Loess;    Permafrost;    Yedoma;    Sand sheet;    Sand sea;    Paleoenvironments;    stratigraphy;    Mammoth steppe;   

DOI  :  10.1016/j.quascirev.2018.01.002

来源: Elsevier

【 摘 要 】

Terrestrial paleoenvironmental records with high dating resolution extending into the last ice age are rare from the western Arctic. Such records can test the synchronicity and extent of ice-age climatic events and define how Arctic landscapes respond to rapid climate changes. Here we describe the stratigraphy and sedimentology of a yedoma deposit in Arctic Alaska (the Carter Section) dating to between 37,000 and 9000 calibrated radiocarbon years BP (37-9 ka) and containing detailed records of loess and sand-sheet sedimentation, soil development, carbon storage, and permafrost dynamics. Alternation between sand-sheet and loess deposition provides a proxy for the extent and activity of the Ikpikpuk Sand Sea (ISS), a large dune field located immediately upwind. Warm, moist interstadial times (ca. 37, 36.3-32.5, and 15-13 ka) triggered floodplain aggradation, permafrost thaw, reduced loess deposition, increased vegetation cover, and rapid soil development accompanied by enhanced carbon storage. During the Last Glacial Maximum (LGM, ca. 28-18 ka), rapid loess deposition took place on a landscape where vegetation was sparse and non-woody. The most intense aeolian activity occurred after the LGM between ca. 18 and 151 a when sand sheets fringing the ISS expanded over the site, possibly in response to increasingly droughty conditions as summers warmed and active layers deepened. With the exception of this lagged LGM response, the record of aeolian activity at the Carter Section correlates with other paleoenvironmental records from unglaciated Siberia and Alaska. Overall, rapid shifts in geomorphology, soils, vegetation, and permafrost portray an ice-age landscape where, in contrast to the Holocene, environmental change was chronic and dominated by aeolian processes. (C) 2018 Elsevier Ltd. All rights reserved.

【 授权许可】

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