CGRG Bibliography of Canadian Geomorphology
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Author : Fox, T.; and Jiskoot, H.
Date : 2011.
Title : Structural glaciology upglacier of a tributary-trunk junction.
Publication : 2011 Annual Meeting of the Western Division of the Canadian Association of Geographers. March 10-12, 2011. Simon Fraser University, Burnaby, BC.
Issue :
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Abstract
Glacier systems are often dendritic, thus composed of a main trunk joined by tributary glaciers. At the confluence of tributaries and trunks a dynamic interaction can take place, resulting in distinct stress fields. An example of this is blocking by a bulging or overriding tributary, commonly observed in surge-type glaciers (Kargel et al., 2005). These stress fields are reflected in specific types of ‘structural glaciology’ (crevasses, faults, foliation, and folding). In order to investigate the blocking potential of a tributary glacier on its trunk we analysed structural glaciological data on Shackleton Glacier, a large valley glacier in the Canadian Rockies. In an area upstream of a tributary-trunk junction we measured the location, orientation (strike/dip), width, depth, length, density, and type of structures for 93 crevasses, 36 crevasse traces, 9 sediment squeezes, and one ‘fountain’. Using GIS analysis, we mapped and evaluated the spatial pattern of the structures. The general ice flow pattern in the study region ranges from slightly extensional (parallel crevasses forming perpendicular to ice flow) to compressive (closing crevasses and crevasse traces, sediment squeezes) to extensional due to a major downstream icefall. Upstream of the active tributary the crevasses are mainly parallel and oriented perpendicular to the incoming tributary, while in the trunk’s flow unit opposite the tributary the crevasses are mostly splayed and oriented perpendicular to oblique to the centre flowline. Combined with 5 years of ice flow measurements at ablation stakes, this study contributes to the prediction of the dynamic effects of glacier recession-related glacier fragmentation.
Bibliography of Canadian Geomorphology