Borehole-Based Characterization of Deep Mixed-Mode Crevasses at a Greenlandic Outlet Glacier ...

• Main Authors: Hubbard, Bryn, Christoffersen, Poul, Doyle, Samuel H, Chudley, Thomas R, Schoonman, Charlotte M, Law, Robert, Bougamont, Marion
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union (AGU) 2021
• Subjects: borehole; crevasse; deep crevasse; glacier; Greenland Ice Sheet; optical televiewer; Greenland; greenlandic; Ice Sheet
• Online Access: https://dx.doi.org/10.17863/cam.70842; https://www.repository.cam.ac.uk/handle/1810/323384

Funder: Aberystwyth University Capital Equipment Fund ... : AbstractOptical televiewer borehole logging within a crevassed region of fast‐moving Store Glacier, Greenland, revealed the presence of 35 high‐angle planes that cut across the background primary stratification. These planes were composed of a bubble‐free layer of refrozen ice, most of which hosted thin laminae of bubble‐rich “last frozen” ice, consistent with the planes being the traces of former open crevasses. Several such last‐frozen laminae were observed in four traces, suggesting multiple episodes of crevasse reactivation. The frequency of crevasse traces generally decreased with depth, with the deepest detectable trace being 265 m below the surface. This is consistent with the extent of the warmer‐than‐modeled englacial ice layer in the area, which extends from the surface to a depth of ∼400 m. Crevasse trace orientation was strongly clustered around a dip of 63° and a strike that was offset by 71° from orthogonal to the local direction of principal extending strain. The traces’ antecedent crevasses ...