Submarine glacial-landform distribution across the West Greenland margin: a fjord–shelf–slope transect through the Uummannaq system (70–71° N)

Abstract

Today, the Greenland Ice Sheet reaches the sea via a number of fast-flowing outlet glaciers that are fed by ice draining from huge interior basins (Rignot & Kanagaratnam 2006). At the Last Glacial Maximum (LGM), the ice sheet expanded to reach the continental shelf break around much of Greenland (O Cofaigh et al. 2013 a ). In the Uummannaq area at c. 70–71° N (Fig. 1a) there is now a 400 km distance between the terminus of Rink Glacier, which drains about 30 000 km2 of the ice sheet, and the shelf edge. This provides a transect from the modern glacier front, through a deep fjord system and adjacent cross-shelf trough, to the continental slope in Baffin Bay. The seafloor is now exposed along this transect and the landforms produced by past glacial activity can be examined using marine-geophysical methods. Deglaciation from the LGM was underway at the shelf edge in Uummannaq Trough by 14.8 kyr ago and from the mid-shelf by 10.9 kyr, and ice had probably retreated back into the fjord system by 9.3 kyr ago (O Cofaigh et al. 2013 a ; Roberts et al. 2013). Fig. 1. Regional bathymetry and shelf architecture of the Uummannaq fjord–shelf–slope system, West Greenland. The location of subsequent figures is also shown. ( a ) Multibeam-bathymetric coverage of the Uummannaq system (located as a red box on the inset location map of Greenland). UI, Ubekendt Island; RF, Rink Fjord. Regional bathymetry from IBCAO v. 3.0. ( b ) Dip-line seismic-reflection profile (130 km long) showing West Greenland continental shelf architecture comprising prograding sedimentary units. ( c ) 110 km long strike profile showing a Late Quaternary glacial trough where erosion has truncated pre-existing reflectors (black arrows). The reflections marked bPP represent the lower boundary of Plio-Pleistocene erosion and glacier-influenced sediments; (b) and (c) are located in (a) …