ABSTRACT: Modeling and interpretation of glaciotectonized sediment in southern and central Alberta: Intergrating GIS, geophysics and geomorphology.

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Abstract

Large-scale glaciotectonic deformation is the faulting and folding of sediments and bedrock due to the compressional and extensional forces imposed by an ice mass. Large-scale features can be observed with the use of air photos and remote sensing where surface expression has been preserved. However, many deformed areas may not have surface expression because subsequent glacial overriding truncated the features. Our goals are (1) to identify the style of glaciotectonism in the three-dimensional subsurface and (2) to isolate important environmental variables that can be used to predict the presence of glaciotectonized sediment where surface expression is absent or altered. Initially, we characterize glaciotectonics in a prairie setting using information gained from sedimentary descriptions of two-dimensional exposures and three-dimensional Electrical Resistivity Imaging (ERI). ERI measures the degree to which a material resists the flow of electrical current introduced into the ground. Electrical resistivity is a function of porosity, saturation, material texture, and resistivity of the pore fluids and the solid phase. For these reasons ERI is especially useful in settings dominated by fine-grained sediments that render other shallow geophysical techniques, such as Ground Penetrating Radar (GPR), ineffective. Several sites were selected to perform ERI along the shores of Travers and McGregor reservoirs in southern Alberta where glaciotectonism is prevalent and exposures accessible. These data allow us to extend the interpretation based on the sedimentary data into three dimensions, therefore, linking the form and process. The ability to map deformed structures away from exposures strengthens our ability to develop conceptual models that are the basis for the second stage of the research. In the second stage of this research we incorporate the information gained from the local sedimentary and geophysical investigations into a regional Geographic Information Systems (GIS) model. The purpose is to create a predictive model for a larger geographical area showing where glaciotectonism is most likely to be present. The model uses multiple variables including data for Quaternary and bedrock geology, and surficial and bedrock topography. This data was selected to investigate the extent to which topography and geology controlled large-scale deformation in central and southern Alberta. The modeling process consists of several steps. First is identifying the relevant variables and to identify the relationships between those attributes. Second is to distinguish between the topographic and geologic characteristics of deformed and undeformed zones in order to determine the likelihood of where glaciotectonism can be expected. Finally, these results are validated with the information gathered from traditional field investigations and ERI data.

Bibliography of Canadian Geomorphology