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Englacial seismic reflectivity: imaging crystal-orientation fabric in West Antarctica

  • Huw J. Horgan (a1) (a2), Sridhar Anandakrishnan (a2) (a3), Richard B. Alley (a2) (a3), Peter G. Burkett (a2) (a3) and Leo E. Peters (a2) (a3)...

Abrupt changes in crystal-orientation fabric (COF), and therefore viscosity, are observed near the base of the ice sheet throughout West Antarctica. We report on active-source seismic observations from WAIS Divide, mid-stream and downstream on Thwaites Glacier, and the onset region of Bindschadler Ice Stream. These data reveal a prevalence of englacial seismic reflectivity in the bottom quarter of the ice sheet. The observed seismic reflectivity is complex but largely bed-conformable, with long-spatial-wavelength features observed in the flow direction and short-wavelength features observed across flow. A correspondence of englacial structures with bed features is also observed. We determine the origin of the reflectivity to be abrupt changes in the COF of ice, based on the following: (1) observations of englacial reflectivity are consistent with current knowledge of COF within ice sheets, (2) englacial reflectivity caused by COF contrasts requires the simplest genesis, especially at ice divides, and (3) amplitude analysis shows that the observed englacial reflectivity can be explained by contrasts in seismic velocity due to COF changes. We note that the downstream increase in the quantity and complexity of observations indicates that direct observations of COF at ice divides likely underestimate the role that fabric plays in ice-sheet dynamics.

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Aki, K. and Richards, P.G.. 1980. Quantitative seismology. Second edition. Sausalito, CA, University Science Books.
Alley, R.B. 1988. Fabrics in polar ice sheets: development and prediction. Science, 240(4851), 493495.
Alley, R.B. 1992. Flow-law hypotheses for ice-sheet modeling. J. Glaciol., 38(129), 245256.
Alley, R.B., Perepezko, J.H. and Bentley, C.R.. 1986a. Grain growth in polar ice: I. Theory. J. Glaciol., 32(112), 415424.
Alley, R.B., Perepezko, J.H. and Bentley, C.R.. 1986b. Grain growth in polar ice: II. Application. J. Glaciol., 32(112), 425433.
Alley, R.B., Gow, A.J., Meese, D.A., Fitzpatrick, J.J., Waddington, E.D. and Bolzan, J.F.. 1997. Grain-scale processes, folding and stratigraphic disturbance in the GISP2 ice core. J. Geophys. Res., 102(C12), 26,81926,830.
Anandakrishnan, S. 1996. Seismic reflections from an internal layer: fabric change or moraine? Eos, 77(17), S150, Spring Meet. Suppl.
Anandakrishnan, S., Fitzpatrick, J.J., Alley, R.B., Gow, A.J. and Meese, D.A.. 1994. Shear-wave detection of asymmetric c-axis fabrics in the GISP2 ice core, Greenland. J. Glaciol., 40(136), 491496.
Bender, M.L., Burgess, E., Alley, R.B., Barnett, B. and Clow, G.D.. 2010. On the nature of the dirty ice at the bottom of the GISP2 ice core. Earth Planet. Sci. Lett., 299(3–4), 466473.
Bennett, H.F. 1968. An investigation into velocity anisotropy through measurements of ultrasonic-wave velocities in snow and ice cores from Greenland and Antarctica. (PhD thesis, University of Wisconsin–Madison.)
Bentley, C.R. 1971a. Seismic anisotropy in the West Antarctic ice sheet. In Crary, A.P., ed. Antarctic snow and ice studies II. Washington, DC, American Geophysical Union, 131177.
Bentley, C.R. 1971b. Seismic evidence for moraine within the basal Antarctic ice sheet. In Crary, A.P., ed. Antarctic snow and ice studies II. Washington, DC, American Geophysical Union, 89 129.
Bentley, C.R. 1972. Seismic-wave velocities in anisotropic ice: a comparison of measured and calculated values in and around the deep drill hole at Byrd Station, Antarctica. J. Geophys. Res., 77(23), 44064420.
Bentley, C.R. and Clough, J.W.. 1972. Antarctic subglacial structure from seismic refraction measurements. In Adie, R.J., ed. Antarctic geology and geophysics. Symposium on Antarctic Geology and Solid Earth Geophysics, 6–15 August 1970, Oslo. Oslo, Universitetsforlaget, 683691.
Bentley, C.R. and Kohnen, H.. 1976. Seismic refraction measurements of internal friction in Antarctic ice. J. Geophys. Res., 81(8), 15191526.
Bentley, C.R. and Ostenso, N.A., 1961. Glacial and subglacial topography of West Antarctica. J. Glaciol., 3(29), 882911.
Blankenship, D.D. and Bentley, C.R.. 1987. The crystalline fabric of polar ice sheets inferred from seismic anisotropy. IAHS Publ. 170 (Symposium at Vancouver 1987 – The Physical Basis of Ice Sheet Modelling), 1728.
Blankenship, D.D., Bentley, C.R., Rooney, S.T. and Alley, R.B.. 1987. Till beneath Ice Stream B. 1. Properties derived from seismic travel times. J. Geophys. Res., 92(B9), 89038911.
Blunier, T. and Brook, E.J.. 2001. Timing of millennial-scale climate change in Antarctica and Greenland during the last glacial period. Science, 291(5501), 109112.
Budd, W.F. and Jacka, T.H.. 1989. A review of ice rheology for ice sheet modelling. Cold Reg. Sci. Technol., 16(2), 107144.
Burkett, P.G. 2000. Ice fabric and active seismology: an investigation and interpretation in central West Antarctica. (MSc thesis, Pennsylvania State University.)
Conway, H. and Rasmussen, L.A.. 2009. Recent thinning and migration of the Western Divide, central West Antarctica. Geophys. Res. Lett., 36(12), L12502. (10.1029/2009GL038072.)
DiPrinzio, C.L., Wilen, L.A., Alley, R.B., Fitzpatrick, J.J., Spencer, M.K. and Gow, A.J.. 2005. Fabric and texture at Siple Dome, Antarctica. J. Glaciol., 51(173), 281290.
Eisen, O., Hamann, I., Kipfstuhl, S., Steinhage, D. and Wilhelms, F.. 2007. Direct evidence for continuous radar reflector originating from changes in crystal-orientation fabric. Cryosphere, 1(1), 110.
Fujita, S. and 6 others. 1999. Nature of radio-echo layering in the Antarctic ice sheet detected by a two-frequency experiment. J. Geophys. Res., 104(B6), 13,01313,024.
Gow, A.J. and Meese, D.A.. 2007a. The distribution and timing of tephra deposition at Siple Dome, Antarctica: possible climatic and rheologic implications. J. Glaciol., 53(183), 585596.
Gow, A.J. and Meese, D.A.. 2007b. Physical properties, crystalline textures and c-axis fabrics of the Siple Dome (Antarctica) ice core. J. Glaciol., 53(183), 573584.
Gow, A.J. and Williamson, T.. 1976. Rheological implications of the internal structure and crystal fabrics of the West Antarctic ice sheet as revealed by deep core drilling at Byrd Station. Geol. Soc. Am. Bull., 87(12), 16651677.
Gow, A.J. and 6 others. 1997. Physical and structural properties of the Greenland Ice Sheet Project 2 ice cores: a review. J. Geophys. Res., 102(C12), 26,55926,575.
Hallet, B., Hunter, L.E. and Bogen, J.. 1996. Rates of erosion and sediment evacuation by glaciers: a review of field data and their implications. Global Planet. Change, 12(1–4), 213235.
Herron, S.L., Langway, C.C. Jr and Brugger, K.A.. 1985. Ultrasonic velocities and crystalline anisotropy in the ice core from Dye 3, Greenland. In Greenland ice core: geophysics, geochemistry, and the environment. Washington, DC, American Geophysical Union, 2331.
Hobbs, P.V. 1974. Ice physics. Oxford, etc., Clarendon Press.
Holland, C.W. and Anandakrishnan, S.. 2009. Subglacial seismic reflection strategies when source amplitude and medium attenuation are poorly known. J. Glaciol., 55(193), 931937.
Hooke, R.LeB. 1973. Structure and flow in the margin of the Barnes Ice Cap, Baffin Island, NWT, Canada. J. Glaciol., 12(66), 423438.
Horgan, H.J. and 6 others. 2008. Complex fabric development revealed by englacial seismic reflectivity: Jakobshavn Isbræ, Greenland. Geophys. Res. Lett., 35(10), L10501. (10.1029/2008GL033712.)
Joughin, I. and 6 others. 2009. Basal conditions for Pine Island and Thwaites Glaciers, West Antarctica, determined using satellite and airborne data. J. Glaciol., 55(190), 245257.
Kohnen, H. 1974. The temperature dependence of seismic waves in ice. J. Glaciol., 13(67), 144147.
Lüthi, A., Funk, M. and Iken, A.. 2003. Indication of active overthrust faulting along the Holocene–Wisconsin transition in the marginal zone of Jakobshavn Isbræ. J. Geophys. Res., 108(B11), 2543. (10.1029/2003JB002505.)
Matsuoka, K. and 6 others. 2003. Crystal-orientation fabrics within the Antarctic ice sheet revealed by a multi-polarization-plane and dual frequency radar survey. J. Geophys. Res., 108(B10), 2499. (10.1029/2002JB002425.)
Medwin, H. and Clay, C.S.. 1977. Acoustical oceanography: principles and applications. New York, Wiley.
Peters, L.E. 2009. A seismic investigation of basal conditions in glaciated regions. (PhD thesis, Pennsylvania State University.)
Peters, L.E. and 6 others. 2006. Subglacial sediments as a control on the onset and location of two Siple Coast ice streams, West Antarctica. J. Geophys. Res., 111(B1), B01302. (10.1029/2005JB003766.)
Peters, L.E., Anandakrishnan, S., Alley, R.B. and Smith, A.M.. 2007. Extensive storage of basal meltwater in the onset region of a major West Antarctic ice stream. Geology, 35(3), 251254.
Rigsby, G.P. 1958. Effect of hydrostatic pressure on velocity of shear deformation on single ice crystals. J. Glaciol., 3(24), 273278.
Ronen, J. and Claerbout, J.F.. 1985. Surface-consistent residual statics estimation by stack-power maximization. Geophysics, 50(12), 27592767.
Röthlisberger, H. 1972. Seismic exploration in cold regions. CRREL Monogr. II-A2a.
Rüger, A. 1997. P-wave reflection coefficients for transversely isotropic models with vertical and horizontal axis of symmetry. Geophysics, 62(3), 713722.
Russell-Head, D.S. and Budd, W.F.. 1979. Ice-sheet flow properties derived from bore-hole shear measurements combined with ice-core studies. J. Glaciol., 24(90), 117130.
Shearer, P.M. 2009. Introduction to seismology. Second edition. Cambridge, etc., Cambridge University Press.
Smith, A.M. 1996. Ice shelf basal melting at the grounding line, measured from seismic observations. J. Geophys. Res., 101(C10), 22,74922,755.
Smith, A.M. 2007. Subglacial bed properties from normal-incidence seismic reflection data. J. Environ. Eng. Geophys., 12(1), 313.
Song, M., Cole, D.M. and Baker, I.. 2005. Creep of granular ice with and without dispersed particles. J. Glaciol., 51(173), 210218.
Thomsen, L. 1986. Weak elastic anisotropy. Geophysics, 51(10), 19541966.
Thorsteinsson, T., Kipfstuhl, J. and Miller, H.. 1997. Textures and fabrics in the GRIP ice core. J. Geophys. Res., 102(C12), 26,58326,599.
Van der Veen, C.J. and Whillans, I.M.. 1994. Development of fabric in ice. Cold Reg. Sci. Technol., 22(2), 171195.
Wilson, C.J.L., Russell-Head, D.S. and Sim, H.M.. 2003. The application of an automated fabric analyzer system to the textural evolution of folded ice layers in shear zones. Ann. Glaciol., 37, 717.
Yilmaz, Ö. 1987. Seismic data processing. Third edition. Tulsa, OK, Society of Exploration Geophysicists.
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