Chronology and sedimentology of a new 2.9 ka annually laminated record from South Sawtooth Lake, Ellesmere Island

QUATERNARY SCIENCE REVIEWS

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Article

Lapointe, Francois^1,2  Francus, Pierre^2,3  Stoner, Joseph S.⁴  Abbott, Mark B.⁵  Balascio, Nicholas L.⁶  Cook, Timothty L.¹  Bradley, Raymond S.¹  Forman, Steven L.⁷  Besonen, Mark⁸  St-Onge, Guillaume^3,9 

[1] Univ Massachusetts, Climate Sci Ctr, Dept Geosci, Amherst, MA 01003 USA

[2] Canada Res Chair Environm Sedimentol, Inst Natl Rech Sci, Ctr Eau Terre Environm, Quebec City, PQ G1K 9A9, Canada

[3] Univ Quebec, Geotop, Montreal, PQ H3C 3P8, Canada

[4] Oregon State Univ, Coll Earth Ocean & Atmospher Sci, Corvallis, OR 97331 USA

[5] Univ Pittsburgh, Dept Geol & Planetary Sci, Pittsburgh, PA 15260 USA

[6] Coll William & Mary, Dept Geol, 251 Jamestown Rd, Williamsburg, VA 23187 USA

[7] Baylor Univ, Coll Arts & Sci, Dept Geol, One Bear Pl 97354, Waco, TX 76798 USA

[8] Texas A&M Univ, Harte Res Inst Gulf Mexico Studies, Corpus Christi, TX 78412 USA

[9] Univ Quebec, Canada Res Chair Marine Geol, Inst Sci Mer Rimouski, 310 Allee Ursulines, Rimouski, PQ G5L 3A1, Canada

关键词: Holocene;    Arctic climate;    Varves;    Paleoclimatology;    Chronology;    Paleomagnetism;   

DOI  :  10.1016/j.quascirev.2019.105875

来源: Elsevier

【 摘 要 】

Few annually laminated (varved) lacustrine records exist in the Arctic, but these high-resolution climate archives are needed to better understand abrupt climate change and the natural mode of climate variability of this sensitive region. This paper presents a new high-resolution 2900-year long varved lake sediment record from the Fosheim Peninsula, Ellesmere Island. The varve chronology is based on multiple varve counts made on high-resolution scanning electron microscope images of overlapping sediment thin sections, and is supported by several independent dating techniques, including Cs-137 and( 210)Pb analysis, one optically stimulated luminescence age located close to the bottom of the composite sequence, and comparison between paleomagnetic variations of this record and the longest High-Arctic varve record, Lower Murray Lake, which confirms the reliability of the Sawtooth chronology. High-resolution backscattered images examined under a scanning electron microscope (SEM) were crucial to giving a more detailed view of sedimentation processes in the lake and thus help to delineate varves more precisely than in conventional image analysis. Fine-scale geochemical analysis reveals that lake sedimentation is mainly clastic and that elemental geochemistry is influenced by grain-size. Principal component analysis of multiple proxies and the coarse grain-size fraction of South Sawtooth Lake display similar fluctuations to the nearby Agassiz Ice Cap delta O-18 record, including lower values during the Little Ice Age cold period. These results show this new high-resolution and continuous record has a reliable varve chronology and is sensitive to temperature variability. South Sawtooth Lake's mean sedimentation rate of 1.67 mm a(-1) is higher than any other sedimentary sequence in the High Arctic providing a unique opportunity for extracting new, high-resolution paleoclimatological and paleoenvironmental record in a region where few other records currently exist. (C) 2019 Elsevier Ltd. All rights reserved.

【 授权许可】

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