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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, BA
We 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 Letters

Volume

401

Pagination

57-69

ISSN

0012-821X

Department/School

Institute for Marine and Antarctic Studies

Publisher

Elsevier Science Bv

Place of publication

Po Box 211, Amsterdam, Netherlands, 1000 Ae

Rights statement

Copyright 2014 Elsevier B.V

Repository Status

  • Restricted

Socio-economic Objectives

Effects of climate change on Antarctic and sub-Antarctic environments (excl. social impacts)

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