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TitleTiming, rates and geomorphic controls on Holocene loess and aeolian sand deposition using multiple chronometric methods, southeastern Cordillera, Alberta, Canada
AuthorWolfe, S AORCID logo; Lian, O B
SourceAeolian Research vol. 50, 100687, 2021 p. 1-16,
Alt SeriesNatural Resources Canada, Contribution Series 20200054
Mediapaper; on-line; digital
File formatpdf; html
NTS82O; 82N/09; 82N/15; 82N/16; 83B/03; 83B/04; 83B/05; 83B/06; 83B/11; 83B/12; 83B/13; 83B/14; 83C; 83D; 83E; 83F; 83G/04; 83G/05
Lat/Long WENS-120.0000 -114.0000 54.0000 51.0000
Subjectssurficial geology/geomorphology; geochronology; Science and Technology; Nature and Environment; Holocene; loess; eolian deposits; tephrochronology; radiocarbon dating; Canadian Cordillera; Climate change; Phanerozoic; Cenozoic; Quaternary
Illustrationslocation maps; tables; ternary diagrams; plots; photographs; stratigraphic columns; schematic sections
ProgramClimate Change Geoscience Permafrost
Released2021 03 06
AbstractGlacier-fed river systems represent potentially significant sediment sources for aeolian processes owing to sediment production, flow seasonality, and winds within mountain settings. We investigate the timing and rates of Holocene loess and aeolian sand deposition in three major river valleys (Bow, North Saskatchewan and Athabasca) of the southeastern Canadian Cordillera through aeolian stratigraphy and dating of sedimentary materials. Source sediments are glacially-derived, seasonally-exposed alluvial deposits. Variation in river morphology promotes source-sediment deposition influenced by bedrock configuration, tributary stream deposition and alluvial fans. Two main settings for aeolian deposition are source-proximal valley-bottom sites and more distal lower-valley sites in sub-alpine and montane forest ecozones. Dating is well-constrained by radiocarbon ages and tephrochronology. Quartz optical dating is complicated, likely owing to minimal recycling of grains and quartz provenance. Mass accumulation rates (MARs) indicate that aeolian deposition was initiated soon after deglaciation and has occurred nearly continuously for at least 10000 years. Loess MARs ranged between 100 and 2500 g?m?? 2?a?? 1 during the Holocene. Rates in the last 3000 years are generally two to three times higher than those observed for earlier periods, and are highest in most recent times. We attribute Holocene accumulation at these sites in general to fluvial source sediment availability and the efficacy of forested valleys as sediment traps. The late Holocene increase in MARs is primarily attributed to increased glacial silt and alluvial sediment supply during neoglacial fluctuations including the Little Ice Age.
Summary(Plain Language Summary, not published)
This study documents eolian deposition along rivers of the southern Canadian Cordillera. Rates of deposition are generally higher than previously considered. River systems with shallow depositional basins are sediment sources. Eolian deposition has occurred due to consistent localized sediment sources. Recent increased rates of deposition may be attributed to increased silt from glaciers.

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