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TitreRates and environmental controls of aeolian dust accumulation, Athabasca River valley, Canadian Rocky Mountains
AuteurHugenholtz, C H; Wolfe, S A
SourceGeomorphology vol. 121, issue 3-4, 2010 p. 274-282,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20090280
ÉditeurElsevier BV
Documentpublication en série
Mediapapier; en ligne; numérique
RégionMontagnes Rocheuses; Jasper Lake; Rivière Athabasca
Lat/Long OENS-118.5000 -118.0000 53.2500 53.0000
Sujetsdépôts éoliens; sables; milieu hydrologique; climat; végétation; sols; loess; bassins versants; géologie des dépôts meubles/géomorphologie; Nature et environnement
Illustrationscartes de localisation; photographies; histogrammes; graphiques; coupes transversales
ProgrammeGéosciences de changements climatiques, Études paléo-environnementales sur les changements climatiques
Diffusé2010 05 06
Résumé(disponible en anglais seulement)
Despite an abundance of sedimentary archives of mineral dust (i.e. loess) accumulations from cold, humid environments, the absence of contemporary process investigations limits paleoenvironmental interpretations in these settings. Dust accumulations measured at Jasper Lake, a seasonally-filled reach of the glaciallyfed Athabasca River in the Canadian Rocky Mountains, are some of the highest contemporary rates recorded to date. High deposition rates, including a maximum of 27,632 kg ha-1 month-1, occur during river lowflow periods, but even the lowest deposition rates, occurring during bankfull periods, exceed other contemporary rates of deposition. High rates of dust deposition may be attributed to geomorphic and climatic controls affecting sediment supply, availability and transport, and biologic factors affecting accumulation. Localized confinement of the Jasper River by tributary river alluvial fans has caused channel expansion upstream, and formation of the shallow depositional basin known as Jasper Lake. This localized sedimentary basin, coupled with large seasonal water level fluctuations and suitably high wind speeds, favors seasonal dust production. In addition, a dense source-proximal coniferous forest stand encourages high dust accumulation, via increased aerodynamic roughness and airflow deceleration. The forest stand also appears to act as an efficient dust filter, with the interception and storage of dust by the forest canopy playing a significant role with regards to secondary fallout and sediment accumulation. Overall, these results provide new insights on the environmental controls of dust entrainment and accumulation in cold, humid settings, and help clarify controls on the formation of Holocene river-sourced loess deposits.