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TitleSediment accumulation rates in subarctic lakes: insights into age-depth modeling from 22 dated lake records from the Northwest Territories, Canada
AuthorCrann, C A; Patterson, R T; Macumber, A L; Galloway, J M; Roe, H M; Blaauw, M; Swindles, G T; Falck, H
SourceQuaternary Geochronology vol. 27, 2015 p. 131-144,
Alt SeriesEarth Sciences Sector, Contribution Series 20140362
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories; Nunavut
NTS75J; 75K; 75L; 75M; 75N; 75O; 76B; 76C; 76D; 76E; 76F; 76G; 76J; 76K; 76L; 85I; 85J; 85O; 85P; 86A
AreaContwoyto Lake
Lat/Long WENS-116.0000 -105.0000 68.0000 62.0000
Subjectssurficial geology/geomorphology; geochronology; sedimentation; lake sediments; sedimentation rates; lake sediment cores; Cenozoic; Quaternary
Illustrationslocation maps; photographs; tables; profiles
Programenvironmental impacts and adaptation in the northern environment, Environmental Geoscience
AbstractAge-depth modeling using Bayesian statistics requires well-informed prior information about the behavior of sediment accumulation. Here we present average sediment accumulation rates for lakes in an Arctic setting, and we examine the variability across space (intra- and inter-lake) and time (late Holocene). The dataset is comprised of over 100 radiocarbon dates, primarily on bulk sediment, from 22 sediment cores obtained from 18 lakes spanning the boreal to tundra ecotone gradients in subarctic Canada. There are four to twenty-five dated horizons per core, depending on the length and character of the sediment records. Accumulation rates were calculated at 100-year intervals from age-depth models constructed using the ¿classical¿ age-depth modeling software Clam. Lakes in boreal settings have the most rapid accumulation rates (mean 20 ? 10 SD years), whereas lakes in tundra settings accumulate at moderate (mean 70 ? 10 SD years) to very slow rates, (>100 yr/cm). Many of the age-depth models demonstrate fluctuations in accumulation that coincide with lake evolution and post-glacial climate change. Ten of our sediment cores obtained sediments as old as c. 9,000 cal BP (BP = years before AD 1950). From between c. 9,000 cal BP and c. 6,000 cal BP, sedimentation was relatively rapid (accumulation rate of 20 to 60 yr/cm). Accumulation rate slowed between c. 5,500 and c. 4,000 cal BP as vegetation expanded northward in response to warming. A short period of rapid accumulation occurred near 1,200 cal BP at three lakes. Our research will assist in the development of age-depth models using Bayesian techniques that require a priori knowledge of how sediment accumulated at a site.
Summary(Plain Language Summary, not published)
Twenty-two sediment cores were collected from 18 lakes along the Tibbitt to Contwoyto Winter Road in the central Northwest Territories, Canada. This route spans boreal forest to tundra ecotones. Establishing the age of the sediments contained in the cores is of critical importance to paleoecological interpretations. We use Bayesian statistics on over 100 radiocarbon dates to constrain and interpret the sediment accumulation rates of the study lakes. Lakes in boreal settings have the most rapid sediment accumulation rates whereas tundra lakes accumulate sediments are very slow rates. From ~9000 years before now sediment accumulated relatively rapidly and slowed between ~5000-4000 before now when climate warmed. A brief period of rapid sediment accumulation occurred near 1200 before now due to a pulse of cooling that resulted in increased erosion.