Holocene Avulsion History of the Lower Saskatchewan Fluvial System, Cumberland Marshes, Saskatchewan–Manitoba, Canada

  1. N. D. Smith2 and
  2. J. Rogers3
  1. G. S. Morozova1 and
  2. N. D. Smith2

Published Online: 17 MAR 2009

DOI: 10.1002/9781444304213.ch18

Fluvial Sedimentology VI

Fluvial Sedimentology VI

How to Cite

Morozova, G. S. and Smith, N. D. (1999) Holocene Avulsion History of the Lower Saskatchewan Fluvial System, Cumberland Marshes, Saskatchewan–Manitoba, Canada, in Fluvial Sedimentology VI (eds N. D. Smith and J. Rogers), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304213.ch18

Editor Information

  1. 2

    Department of Geosciences, 214 Bessey Hall, University of Nebraska, Lincoln, NE 68588-0340, USA

  2. 3

    Cape Town, South Africa

Author Information

  1. 1

    University of Illinois at Chicago, Department of Earth & Environmental Sciences (m/c 186), 845 West Taylor Street, Chicago, IL 60607-7059, USA

  2. 2

    Department of Geosciences, 214 Bessey Hall, University of Nebraska, Lincoln, NE 68588-0340, USA

Publication History

  1. Published Online: 17 MAR 2009
  2. Published Print: 7 OCT 1999

ISBN Information

Print ISBN: 9780632053544

Online ISBN: 9781444304213

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Keywords:

  • Holocene avulsion history of lower Saskatchewan fluvial system Cumberland Marshes, Saskatchewan–Manitoba, Canada;
  • Holocene avulsion history and alluvial stratigraphy of lower Saskatchewan fluvial system;
  • Cumberland Marshes - the ‘Saskatchewan Delta’;
  • climatic and hydrological setting;
  • stratigraphy and facies of holocene alluvium;
  • deposition of upper complex;
  • avulsion styles;
  • holocene alluvial history of Saskatchewan River at Cumberland marshes;
  • major controls of alluvial history

Summary

The Holocene avulsion history and alluvial stratigraphy of the lower Saskatchewan fluvial system in the Cumberland Marshes, central Canada, were studied from nearly 200 boreholes. These data, together with 48 radiocarbon dates of organic-rich deposits, allowed access to fluvial history back to c. 5400 yr BP. Throughout the middle and late Holocene, repeated avulsions, the most recent initiated in the 1870s, have formed prominent channel belts, most of which now stand as abandoned alluvial ridges separated by floodbasin depressions. Nine principal avulsions have occurred in the past 5400 yr. Most avulsions originated near the western edge of the Cumberland Marshes, where the Saskatchewan River undergoes an abrupt reduction in gradient. Major channel belts were active for up to 2400 yr, indicating that channel belts at times coexisted. Holocene sediments show evidence of two basic avulsion styles, channel reoccupation and splay-complex progradation. Avulsion styles and alluvial stratigraphy were affected by climate change, which influenced levels and areal extents of floodplain lakes and wetlands. Climate changes also influenced the discharge, flood regime and sediment load of the Saskatchewan River. Holocene alluvium that formed before c. 5400 yr BP is composed of mainly silty and sandy sediments and represents drier and warmer climates of the Hypsithermal Interval. Following a change toward cooler and wetter conditions between 5400 and c. 2600 yr BP, floodplain lakes became higher and more extensive, resulting in widespread deposition of a middle layer of lacustrine and wetland deposits. Beginning approximately 2600 yr BP, the lakes became increasingly filled by fluvial deposits, resulting in the formation of an upper complex of silty and sandy deposits. Avulsion by splay-complex progradation characterized floodplain evolution during the period of lake-level rise between 5400 and 2600 yr BP, whereas avulsions since then involved both reoccupation and splay-complex progradation.