CGRG Bibliography of Canadian Geomorphology
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Author : Cuven, S.
Date : 2005.
Title : Spatial and temporal variability in sedimentation in an High Arctic lake.
Publication : 35th Annual International Arctic Workshop. March 9-12, 2005. Timms Centre for the Arts, University of Alberta, Edmonton, Alberta, Canada.
Issue :
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Abstract
Two annually laminated lakes at Cape Bounty, Melville Island, Nunavut, are the subject of an interdisciplinary investigation lead by Queen’s University. The main objectives of the research project are to investigate present and past sedimentary processes within the watershed and the lakes, in order to evaluate changes of the hydrology and the climate of this region of the High Arctic. Our specific objective is to build a map of the spatial and temporal variations of sedimentary fluxes at an annual resolution. We investigate eight short cores (50 cm) sampled along two transects in West lake. In all the cores, the sediment is exclusively terrigeneous, forming ± 2 mm thick laminations that consist of alternating silt and clay layers. Here, we present preliminary data from MSCL (Multi Sensor Core Logger), mainly Gamma Ray Attenuation Porosity Evaluator (GRAPE) and point sensor magnetic susceptibility, and X-ray computed tomography (CT-scans) from the eight cores. Magnetic susceptibility profiles, along with lamination thicknesses allow the correlation between the cores. A 137Cs profile from another core (Queen’s Team) provides an absolute time control. To calculate annual sedimentary fluxes for each core, we need to determine the annual bulk density of the sediment. Because analytical resolution of GRAPE is larger than the average lamination thickness, we use relative density information provided by CT-scans that has a much high spatial resolution, i.e. 1 mm. Then, we attempt to calibrate numerical X-ray computed tomography (CT) values with wet bulk density inferred from GRAPE in order to obtain absolute density values. A calibration on homogeneous marine sediments was previously developed by Orsi and Anderson (1999) with a strong correlation (R2=0.98), but high frequency variation of the terrigeneous input considerably influence the scanner response. Finally, we observe time intervals with strong fluctuations in relative density curve, and other intervals with little variation, which
Bibliography of Canadian Geomorphology