Subglacial melt channels and fracture in the floating part of Pine Island Glacier, Antarctica
| Autor: | Pierre Dutrieux, Hugh F. J. Corr, David G. Vaughan, Duncan J. Wingham, Adrian Jenkins, R. Bindschadler, Patricia Vornberger, G. Hilmar Gudmundsson, T. Newman |
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| Rok vydání: | 2012 |
| Předmět: |
Atmospheric Science
010504 meteorology & atmospheric sciences Ice stream Soil Science Aquatic Science Oceanography 01 natural sciences Ice shelf 010305 fluids & plasmas law.invention Crevasse Geochemistry and Petrology law 0103 physical sciences Earth and Planetary Sciences (miscellaneous) 14. Life underwater Geomorphology 0105 earth and related environmental sciences Earth-Surface Processes Water Science and Technology geography geography.geographical_feature_category Ecology Paleontology Forestry Glacier Subglacial stream Glaciology Geophysics Space and Planetary Science Fracture (geology) Hydrostatic equilibrium Geology |
| Zdroj: | Journal of Geophysical Research: Earth Surface. 117 |
| ISSN: | 0148-0227 |
| DOI: | 10.1029/2012jf002360 |
| Popis: | [1] A dense grid of ice-penetrating radar sections acquired over Pine Island Glacier, West Antarctica has revealed a network of sinuous subglacial channels, typically 500 m to 3 km wide, and up to 200 m high, in the ice-shelf base. These subglacial channels develop while the ice is floating and result from melting at the base of the ice shelf. Above the apex of most channels, the radar shows isolated reflections from within the ice shelf. Comparison of the radar data with acoustic data obtained using an autonomous submersible, confirms that these echoes arise from open basal crevasses 50–100 m wide aligned with the subglacial channels and penetrating up to 1/3 of the ice thickness. Analogous sets of surface crevasses appear on the ridges between the basal channels. We suggest that both sets of crevasses were formed during the melting of the subglacial channels as a response to vertical flexing of the ice shelf toward the hydrostatic condition. Finite element modeling of stresses produced after the formation of idealized basal channels indicates that the stresses generated have the correct pattern and, if the channels were formed sufficiently rapidly, would have sufficient magnitude to explain the formation of the observed basal and surface crevasse sets. We conclude that ice-shelf basal melting plays a role in determining patterns of surface and basal crevassing. Increased delivery of warm ocean water into the sub-ice shelf cavity may therefore cause not only thinning but also structural weakening of the ice shelf, perhaps, as a prelude to eventual collapse. |
| Databáze: | OpenAIRE |
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