You have entered the website of the Water and Environmental Research Institute of the Western Pacific (WERI) at the University of Guam. We are currently six faculty and five staff and our mission is to seek solutions through research, teaching and outreach programs, to issues and problems associated with the location, production, distribution and management of freshwater resources in Guam, the CNMI and the FSM.
Interdisciplinary study of the potential role of subglacial sediment in ice sheet movement.
Background
Exposure of glacial till layers in bluffs above the Nelson River, northern Manitoba, from which specimens of the Sky Pilot Till, deposited by the Laurentide Ice Sheet, were obtained.
We have recently completed a set of geotechnical experiments (Sane et al., 2008) using the Disturbed State Concept (DSC) model (Desai, 2001) to evaluate the rheology of two regionally significant North American Pleistocene tills (Carlson et al., 2004). The results suggest that soft beds could, at certain stages of deformation–assuming sufficiently strong coupling at the ice-till interface–support shear stresses of about 20 kPa, substantially greater than the residual strengths measured in other tills by Kamb (1991) and Iverson et al (1997; Iverson et al., 1998) (<3 kPa). Having thus developed the DSC model for the fully-coupled case (in which there is assumed to be no “sliding” or “slippage” between the basal ice and the underlying bed of “soft” (i.e., water-saturated) till, the research team proposes now to extend the application of the DSC model to the mechanics of relative motion at the interface between the basal ice and underlying till. The proposed work will utilize the specialized Cyclic Multi-Degree-of-Freedom (CYMDOF) shear device at the University of Arizona´s Constitutive Modeling Laboratory, which has been developed and proven in previous advanced geotechnical research applications. The CYMDOF test box will be modified to accommodate ice-till interface specimens with controlled configurations guided by insights gained from continued field study by the research team and from previous observations published by others. The model will be validated by independent tests and then implemented in numerical simulations to predict the motion resulting from the combined effects of interface motion and deformation in the till and ice. The proposed work will take advantage of previously proven methodology and the mathematical and numerical models developed and tested in the previous project.
Applications of the research
Ice sheet modelers have long sought a reliable model for soft-bedded ice sheet movement. Despite the important role of slip in ice movement,however, no truly predictive models have yet been developed for slip of ice over a till surface. The results of this project will be an important contribution toward the ultimate development of sophisticated ice sheet models that could provide reliable predictions of growth, decay, and stability of glaciers and ice sheets–both Pleistocene and modern–and their interaction with climate. Such models may also yield new insights into landscape evolution in glacial terrains, such as whether soft-bed deformation could have mobilized sufficient sediment flux to account for the large volumes of till in the Midwestern United States or the large deposits of glacigenic material in the Barents Sea. Answers to such questions have applications to important economic activities in glaciated regions, including water resource management and mineral prospecting and mining.
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