Laboratory observations of sediment entrainment by freezing supercooled water

Simon James Cook, Peter G. Knight, Deborah A. Knight, Richard I. Waller

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Basal ice produced by glaciohydraulic supercooling is typically characterised by high proportions of silt, and has previously been attributed to the preferential filtering of silt from sediment-laden water percolating through frazil ice. Silt-dominance has come to be considered as diagnostic of supercooling. We test the hypothesis that freezing sediment-laden supercooled water necessarily produces ice that is dominated by silt by simulating two freezing processes simultaneously under laboratory conditions: (1) percolation of sediment-laden water through frazil ice; and (2) turbulent supercooling and subsequent freezing of sediment-laden water. In experiments using unmixed sand, silt or clay particle sizes both processes entrained sand most effectively and silt least effectively. In experiments using a sediment mixture dominated by medium to coarse silt, both processes produced ice facies dominated by particle sizes between fine sand and coarse silt. Our results indicate that silt-dominance should therefore not be expected for supercooled freeze-on, and is not a diagnostic signature for supercooling. The silt-dominated character of basal ice types associated with supercooling may owe their silt-dominance to a silt-dominated sediment supply, rather than to the freezing process.
Original languageEnglish
Pages (from-to)351–362
JournalGeografiska Annaler: Series A, Physical Geography
Volume94
Issue number3
DOIs
Publication statusPublished - Sept 2012

Keywords

  • basal ice
  • freezing processes
  • laboratory experiments
  • sediment entrainment
  • supercooling

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