Controls on the formation of turbidity current channels associated with marine-terminating glaciers and ice sheets.

Submarine channels, and the sediment density flows which form them, act as conduits for the transport of sediment, macro-nutrients, fresher water and organic matter from the coast to the deep sea. These systems are therefore significant pathways for global sediment and carbon cycles. However, the conditions that permit or preclude submarine channel formation are poorly understood, especially when in association with marine-terminating glaciers. Here, using swath-bathymetric data from the inner shelf and fjords of northwest and southeast Greenland, we provide the first paper to analyse the controls on the formation of submarine channels offshore of numerous marine-terminating glaciers. These data reveal 37 submarine channels: 11 offshore of northwest Greenland and 26 offshore of southeast Greenland. The presence of channels is nearly always associated with: (1) a stable glacier front, as indicated by the association with either a moraine or grounding-zone wedge; and (2), a consistent seaward sloping gradient. In northwest Greenland, turbidity current channels are also more likely to be associated with larger glacier catchments with higher ice and meltwater fluxes which provide higher volumes of sediment delivery. However, the factors controlling the presence of channels in northwest and southeast Greenland are different, which suggest some complexity about predicting the occurrence of turbidity currents in glacier-influenced settings. Future work on tidewater glacier sediment delivery rates by different subglacial processes, and the role of grain size and catchment/regional geology is required to address uncertainties regarding the controls on channel formation. • Most complete inventory of submarine channels offshore Greenland • Submarine channels are more common offshore of southeast Greenland. • Controls on channel formation are defined and used to construct conceptual model. • Observations from other glacier-influenced settings show support for these criteria. [ABSTRACT FROM AUTHOR]