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Dilatant till facilitates ice-stream flow in northeast Greenland
journal contribution
posted on 2023-05-18, 13:41 authored by Christianson, K, Peters, LE, Alley, RB, Anandakrishnan, S, Jacobel, RW, Riverman, KL, Muto, A, Keisling, BAWe present radio-echo sounding (RES), global positioning system (GPS), and active-source seismic data across the central portion of the Northeast Greenland Ice Stream (NEGIS). NEGIS widens downglacier from a small region of high geothermal flux near the ice divide. Our data reveal high-porosity (40+%) water-saturated till lubricating the ice stream. Ice accelerates and thins as it flows into NEGIS, producing marginal troughs in surface topography. These troughs create steep gradients in the subglacial hydropotential that generate parallel “sticky” and “slippery” bands beneath the shear margins. The low-porosity “sticky” sediment bands limit ice entrainment across the margins and thus restrict further widening, producing the long, narrow, and relatively stable ice stream. However, the observed relations among surface elevation, basal water routing, broad sedimentary drape, and till dilatancy suggest that rapid shifts in ice dynamics are possible, including rapid transmission of ocean forcing inland. The source and routing of the subglacial till are unclear, but our data help constrain hypotheses.
History
Publication title
Earth and Planetary Science LettersVolume
401Pagination
57-69ISSN
0012-821XDepartment/School
Institute for Marine and Antarctic StudiesPublisher
Elsevier Science BvPlace of publication
Po Box 211, Amsterdam, Netherlands, 1000 AeRights statement
Copyright 2014 Elsevier B.VRepository Status
- Restricted