The role of meltwater in high-latitude trough-mouth fan development: The Disko Trough-Mouth Fan, West Greenland
journal contributionposted on 2018-04-10, 08:18 authored by Colm O Cofaigh, K.A. Hogan, Anne E. Jennings, S. Louise Callard, Julian A. Dowdeswell, R. Noormets, Jeffrey EvansJeffrey Evans
The Disko Trough-Mouth Fan (TMF) is a major submarine sediment fan located along the central west Greenland continental margin offshore of Disko Trough. The location of the TMF at the mouth of a prominent cross-shelf trough indicates that it is a product of repeated glacigenic sediment delivery from former fast-flowing outlets of the Greenland Ice Sheet, including an ancestral Jakobshavn Isbrae, which expanded to the shelf edge during successive glacial cycles. This study focuses on the uppermost part of the fan stratigraphy and analyses multibeam swath bathymetry and sub-bottom profiler records, supplemented by a series of vibrocores up to 6 m in length. The swath bathymetry data show that the surface of the fan is prominently gullied and channelled with channels extending downslope from a series of shelf-edge incising gullies. Sub-bottom profiles from across- and down-fan show that the fan sediments are often acoustically stratified. Glacigenic-debris flows (GDFs) were recovered in sediment cores from the uppermost slope but they are absent in cores from elsewhere on the fan. Instead, glacimarine lithofacies in the Disko TMF are dominated by turbidites, hemipelagic sediments and IRD. The gullied and channelled surface of the fan implies erosion at the base of dense, sediment-laden, turbidity currents related to the delivery of meltwater and sediment from an ice sheet grounded at the shelf edge. Such meltwater-related fans have been documented previously on mid-latitude, glacier-influenced margins, but they have rarely been described from high-latitude settings. Although GDFs are often regarded as the building blocks of TMFs, the morphology and sedimentary architecture of the uppermost, Late Quaternary part of the Disko TMF indicates that it represents a clear example of a fan in which sediment delivery is strongly influenced by meltwater. This implies that there is a spectrum of TMFs on glaciated continental margins that reflects the relative dominance of meltwater processes vs. GDFs. It highlights the variability in fan morphology and mechanisms of sediment delivery on high-latitude TMFs and shows that the classic Polar North Atlantic model of GDF dominated fans is but one of a number of styles for such large-scale, high-latitude glacimarine sedimentary depocentres.
The data for this study were collected during cruise JR175 of the RSS James Clark Ross to West Greenland in 2009 which was funded by Natural Environment Research Council (NERC) grants NE/D001951/1 and NE/D001986/1. Funding for this research was also provided by the United States National Science Foundation awards: NSF OPP-0713755 and NSF P2C2-1203492 to the University of Colorado. KAH was supported by the British Antarctic Survey ‘Polar Science for Planet Earth’ programme, also funded by NERC.
- Social Sciences
- Geography and Environment
Published inMarine Geology
CitationO COFAIGH, C. ... et al, 2018. The role of meltwater in high-latitude trough-mouth fan development: The Disko Trough-Mouth Fan, West Greenland. Marine Geology, 402, pp.17-32.
- AM (Accepted Manuscript)
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NotesThis paper was accepted for publication in the journal Marine Geology and the definitive published version is available at https://doi.org/10.1016/j.margeo.2018.02.001