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A simple model for the influence of push-morainal banks on the calving and stability of glacial tidewater termini

  • Mark P. Fischer (a1) and Ross D. Powell (a1)

Abstract

Push-morainal banks at the grounding lines of tidewater termini of temperate glaciers are the source of two types of restraining forces operating at the glacier terminus. Horizontal normal forces derive from the lateral support and transport of the bank of sediment at the terminus, whereas a horizontal shear force operates along the base of a bank pushed in front of an advancing glacier. The simple model we present suggests that bank-related restraining forces are significantly larger than the restraining force derived from the hydrostatic pressure of water adjacent to the submerged terminus of a glacier. During glacier advance, restraining forces continually increase, resulting in decreasing flow rates, glacier thickening and the eventual cessation of advance. During retreat, restraining forces continually decrease, resulting in increasing flow rates, glacier thinning and the potential for unstable, rapid, sustained retreat. The normal, seasonal, oscillatory advance retreat cycle of a glacier is moderated by restraining forces associated with push moraines. Unstable retreat is likely initiated when bank-related restraining forces fall below some threshold value during the seasonal retreat cycle. Calving is not a primary cause of glacier retreat, but is more likely a short-term response to increased flow rates. Increased flow rates result in glacier thinning and an approach toward buoyancy, both of which fluctuate seasonally in accordance with bank-related restraining forces.

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References

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Alley, R. B. 1991. Sedimentary processes may cause fluctuations of tidewater glaciers. Ann. Glaciol., 15, 119124.
Brown, C. S., Meier, M. F. and Post, A.. 1982. Calving speed of Alaska tidewater glaciers, with application to Columbia Glacier. U.S. Geol. Surv. Prof. pap. 1258-C.
Cai, J., Powell, R. D., Cowan, E. A. and Carlson, P. R.. In press. Substantiating seismic reflection interpretations of temperate glacimarine sediment (Alaska) by comparison with known depositional processes and lithofacies. Mar. Geol.
Chapple, W. M. 1978. Mechanics of thin-skinned fold and thrust belts. Geol. Soc. Am. Bull., 89(8), 11891198.
Cowan, E. A. and Powell, R. D.. 1991. Ice-proximal sediment accumulation rates in a temperate glacial fjord, southeastern Alaska. In Anderson, J. B. and Ashley, G. M., eds. Glacial marine sedimentation; paleoclimatic significance. Boulder, CO, Geological Society of America, 6173. (GSA Special Paper 261.)
Dackombe, R. V. and Gardiner, V. 1983. Geomorphological field manual. London, Allen and Unwin.
Dahlen, F. A. 1984. Noncohesive critical Coulomb wedges: an exact solution. J. Geophys. Res., 89(B2). 10, 12510,133.
Davis, D., Suppe, J. and Dahlen, F. A.. 1983. Mechanics of fold-and-thrust bells and accretionary wedges. J. Geophys. Res.,. 88(B2), 11531172.
Elliott, D. 1976. The energy balance and deformation mechanisms of thrust sheets. Philos. Trans. R. Soc. London, Ser. A, 238, 289312.
Hubbert, M. K. and Rubey, W. W.. 1959. Role of fluid pressure in mechanics of overthrust faulting. 1. Mechanics of fluid-filled porous solids and its application to overthurst faulting. Geol. Soc. Am. Bull., 70(2), 115166.
Hughes, T. 1992. Theoretical calving rates from glaciers along ice walls grounded in water of variable depths. F. Glaciol., 38 (129), 282294.
Hunter, L. E. 1994. Grounding-line systems and glacier mass balance of modern temperate glaciers and their effect on glacier stability. (Ph.D. thesis, Northern Illinois University.)
Hunter, L. E., Powell, R. D. and Smith, G. W.. 1996a. Facies architecture and ground-line fan processes of morainal banks during the deglaciation of coastal Maine, U.S.A. Geol. Soc, Am. Bull., 108(8), 10221038.
Hunter, L. E., Powell, R. D. and Lawson, D. E.. 1996b. Morainal-bank sediment budgets and their influence on the stability of tidewater termini of valley glaciers entering Glacier Bay, Alaska, U.S.A. Ann. Glaciol., 22, 211216.
Jaeger, J. C. and Cook, N. G. W.. 1979. Fundamentals of rock mechanics. Third edition. London, Chapman and Hall.
Kamb, B. 1987. Glacier surge mechanism based on linked cavity configuration of the basal water conduit system. J. Geophys. Res., 92(B9), 90839100.
Krimmel, R. M. and Vaughn, B. H.. 1987. Columbia Glacier, Alaska: changes in velocity 1977-1986. J. Geophys. Res., 92(B9), 89618968.
Lambe, T. W. and Whitman, R. V.. 1969. Soil mechanics. New York, etc., John Wiley and Sons.
Mayo, L. R. 1988. Advance of Hubbard Glacier and closure of Russell Fiord, Alaska-environmental effects and hazards in the Yakutat area. U.S. Geol. Surv. Circ. 1016, 416.
Meier, M. F. and Post, A.. 1987. Fast tidewater glaciers. J. Geophys. Res., 92(B9),90519058.
Meier, M. F., Rasmussen, L. A. and Miller, D. S.. 1985a. Columbia Glacier In 1984: disintegration under way. U.S. Geol. Surv. Open File Rep. 8581,
Meier, M. F., Rasmussen, L. A., Krimmel, R. M., Olsen, R. W. and Frank, D.. 1985b, Photogrammetric determination of surface altitude, terminus position, and ice velocity of Columbia Glacier, Alaska, U.S. Geol. Surv. Prof. Pap. 1258-F.
Meier, M. and 9 others. 1994. Mechanical and hydrologie basis for the rapid motion of a large tidewater glacier. 1. Observations. J. Geophys. Res., 99(B8), 15, 21915,229.
Post, A. 1975. Preliminary hydrography and historic terminal changes of Columbia Glacier, Alaska. U.S. Geol. Surv. Hydrol. Invest. Atlas HA-559.
Powell, R. D. 1983. Glacial-marine sedimentation processes and lithofacies of temperate tidewater glaciers, Glacier Bay, Alaska, In Molnia, B. F., ed. Glacial-marine sedimentation. New York, etc., Plenum Press, 185232.
Powell, R. D. 1988. Processes and facies of temperate and sub-polar glaciers with tidewater fronts. Boulder, CO, Geological Society of America. (Geological Society of America Short Course Notes.)
Powell, R. D. 1991. Grounding-line systems as second-order controls on fluctuations of tidewater termini of temperate glaciers. In Anderson, J. B. and Ashley, G. M., eds. Glacial marine sedimentation; paleoclimatic significance. Boulder, CO, Geological Society of America, 7593. (GSA Special Paper 261).
Seramur, K. C., Powell, R. D., Carlson, P. R. and Cowan, E. A.. 1997. Muir Inlet morainal bank complex. Glacier Bay, S. E. Alaska. In Davies, T. A. and others, eds, Glaciated continanal margins: an atlas of acoustic images. London, Chapman and Hall, 99293.
Van der Veen, C.J. 1996. Tidewater calving. J. Glacial., 42(141), 375385.
Van der Wateren, D. 1986. Structural geology and sedimentology of the Dammer Berge push moraine, FRG. In Van der Meer, J. J. M., ed. Tills and glacioteconics. Rotterdam and Boston, A. A. Balkema, 157182.
Van der Wateren, F. M. 1994. Processes of glaciotectonism. In Mailman, A., ed. The geological deformation of sediments. New York, Chapman and Hall, 309335.
Zoback, M. D. and Healy, J. H.. 1984. Friction, faulting and in situ stress. Annales Geophysicae, 2, 689698.

A simple model for the influence of push-morainal banks on the calving and stability of glacial tidewater termini

  • Mark P. Fischer (a1) and Ross D. Powell (a1)

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