Sedimentary pellets as an icecover proxy in a Hig

Authors: Jessica D Tomkins Scott F Lamoureux Dermot Antoniades Warwick F Vincent

Publish Date: 2008/10/01

Volume: 41, Issue: 1, Pages: 225-242

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Abstract

Sediment aggregates “sedimentary pellets” within the sedimentary record of Lake A 83°00′ N 75°30′ W Ellesmere Island Canada are used to construct a 1000 year proxy record of icecover extent and dynamics on this perennially icecovered High Arctic lake These pellets are interpreted to form during fall or early winter when littoral sediment adheres to ice forming around the lake’s periphery or during summer through the development of anchor ice The sediment likely collects in ice interstices and is concentrated in the upper ice layers through summer surface ice melt and winter basal ice growth The pellets remain frozen in the ice until a summer or series of summers with reduced ice cover allows for their deposition across the lake basin Sedimentary pellet frequency within multiple sediment cores is used to develop a chronology of icecover fluctuations This proxy icecover record is largely corroborated by a record of unusual sedimentation in Lake A involving ironrich darkorange to red laminae overlying more diffuse laminae with a lighter hue This sediment sequence is hypothesized to represent years with reduced ice cover through increased chemocline ventilation and iron deposition During the past millennium the most notable period of inferred reduced ice cover is ca 1891 AD to present Another period of ice cover mobility is suggested ca 1582–1774 AD while persistent ice cover is inferred during the 1800s and prior to 1582 AD The proxy icecover record corresponds well with most regional meltseason proxy temperature and paleoecological records especially during the 1800s and 1900sThis research was funded by the Natural Sciences and Engineering Research Council of Canada ArcticNet a Canadian Network of Centres of Excellence the Canada Research Chair program and the International Polar Year program Logistical support from Polar Continental Shelf Project Natural Resources Canada and Parks Canada is gratefully acknowledged Additional support from the Northern Scientific Training Program Royal Canadian Geographical Society Association of Canadian Universities for Northern Studies Canadian Northern Studies Trust Ontario Graduate Scholarship program Queen’s University and le fonds québécois de la recherche sur la nature et les technologies is greatly appreciated We also thank Jérémie Pouliot Julie Veillette Denis Sarrazin Université Laval Eric Bottos McGill University and John Ennis United Helicopters for their excellent field assistance Dr Raymond Bradley provided access to analyse thin sections created from previous studies of Lakes A B C1 C2 and C3 Dr Derek Mueller University of Alaska Fairbanks shared satellite imagery observations of lake ice extents and Dr Claude Belzile Université Laval shared field observations Constructive comments from Dr Rod Smith Geological Survey of Canada Natural Resources Canada and three anonymous reviewers improved this manuscript This is Polar Continental Shelf Project contribution number 01408

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