The physiography of High Arctic cross-shelf troughs

A comprehensive inventory of High Arctic cross-shelf troughs is compiled from International Bathymetric Chart of the Arctic Ocean (IBCAO) bathymetric data (v. 3.0). The location of 75 cross-shelf troughs is presented alongside a synthesis of their key physiographic characteristics and available glacial-geological evidence. The troughs are interpreted to have been occupied intermittently and eroded by marine-terminating ice streams that traversed the shelf during at least one, and often many Quaternary full-glacial periods. Considerable variation in cross-shelf trough physiography exists in the High Arctic; trough lengths range between 35 and 1400 km, widths from 12 to 260 km, and maximum depths from 200 to 1000 m. The longest cross-shelf troughs extend through inter-island channels on the Beaufort Sea, Queen Elizabeth Islands and Barents-Kara Sea margins. The gradient of the upper-slope beyond High Arctic glacial troughs, which ranges between 0.3° and 13°, is shown to have a negative relationship with palaeo-ice stream drainage basin area and trough length. Glacial-sedimentary depocentres or trough-mouth fans (TMFs) are inferred on the basis of bathymetric and, where available, seismic evidence, to exist beyond the majority of High Arctic cross-shelf troughs. Evidence of shelf progradation or TMF development is absent from the slope beyond several High Arctic troughs, probably as a result of limited sediment supply to the margin and/or sediment by-passing of the upper-slope. On the South Greenland continental margin, it is likely that steep slopes prevented the development of significant glacial-sedimentary depocentres beyond cross-shelf troughs or that glacigenic debris has been removed from the upper-slope by submarine slope failure.