Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland ...

• Main Authors: Hofstede, Coen, Christoffersen, P, Hubbard, Bryn, Doyle, Samuel, Young, Tun Jan, Diez, Anja, Eisen, Olaf, Hubbard, Alun
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell 2018
• Subjects: subglacial; sliding; deformation; anisotropy; patches; seismic; Greenland; Uummannaq Fjord; glacier; Ice Sheet; Uummannaq
• Online Access: https://dx.doi.org/10.17863/cam.21073; https://www.repository.cam.ac.uk/handle/1810/274391

Outlet glaciers of the Greenland Ice Sheet transport ice from the interior to the ocean and contribute directly to sea level rise because because discharge and ablation often exceed the accumulation. To develop a better understanding of these fast flowing glaciers, we investigate the basal conditions of Store Glacier, a large outlet glacier flowing into Uummannaq Fjord in West Greenland. We use two crossing seismic profiles acquired near the centreline, 30 km upstream of the calving front, to interpret the physical nature of the ice and bed. We identify one notably englacial and two notably subglacial seismic reflections on both profiles. The englacial reflection represents a change in crystal orientation fabric, interpreted to be the Holocene–Wisconsin transition. From Amplitude Versus Angle (AVA) analysis we infer that the deepest 80 m of ice of the parallel-flow profile below this reflection is anisotropic with an enhancement of simple shear of 2. The ice is underlain by 45 m of unconsolidated sediments, ...