Seafloor geomorphology and glacimarine sedimentation associated with fast-flowing ice sheet outlet glaciers in Disko Bay, West Greenland

Katharina Streuff, Colm Ó. Cofaigh, Kelly Hogan, Anne Jennings, Jeremy M. Lloyd, Riko Noormets, Tove Nielsen, Antoon Kuijpers, Julian A. Dowdeswell, Wilhelm Weinrebe

Research output: Contribution to journalArticleResearchpeer-review

19 Citations (Scopus)

Abstract

Fast-flowing outlet glaciers currently drain the Greenland Ice Sheet (GIS), delivering ice, meltwater and debris to the fjords around Greenland. Although such glaciers strongly affect the ice sheet's mass balance, their glacimarine processes and associated products are still poorly understood. This study provides a detailed analysis of lithological and geophysical data from Disko Bay and the Vaigat Strait in central West Greenland. Disko Bay is strongly influenced by Jakobshavn Isbræ, Greenland's fastest-flowing glacier, which currently drains ∼7% of the ice sheet. Streamlined glacial landforms record the former flow of an expanded Jakobshavn Isbræ and adjacent GIS outlets through Disko Bay and the Vaigat Strait towards the continental shelf. Thirteen vibrocores contain a complex set of lithofacies including diamict, stratified mud, interbedded mud and sand, and bioturbated mud deposited by (1) suspension settling from meltwater plumes and the water column, (2) sediment gravity flows, and (3) iceberg rafting and ploughing. The importance of meltwater-related processes to glacimarine sedimentation in West Greenland fjords and bays is emphasised by the abundance of mud preserved in the cores. Radiocarbon dates constrain the position of the ice margin during deglaciation, and suggest that Jakobshavn Isbræ had retreated into central Disko Bay before 10.6 cal ka BP and to beyond Isfjeldsbanken by 7.6–7.1 cal ka BP. Sediment accumulation rates were up to 1.7 cm a −1 for ice-proximal glacimarine mud, and ∼0.007–0.05 cm a −1 for overlying distal sediments. In addition to elucidating the deglacial retreat history of Jakobshavn Isbræ, our findings show that the glacimarine sedimentary processes in West Greenland are similar to those in East Greenland, and that variability in such processes is more a function of time and glacier proximity than of geographic location and associated climatic regime.

Original languageEnglish
Pages (from-to)206-230
Number of pages25
JournalQuaternary Science Reviews
Volume169
DOIs
Publication statusPublished - 1 Aug 2017

Keywords

  • Deglaciation
  • Glacial geomorphology
  • Greenland
  • Holocene
  • Sedimentology
  • Tidewater glaciers

Programme Area

  • Programme Area 3: Energy Resources

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