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Application of the surface azimuthal electrical resistivity survey method to determine patterns of regional joint orientation in glacial tills

Environmental Geosciences

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DOI: 10.1306/eg.04061010002

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Abstract

Joints within unconsolidated material such as glacial till can be primary avenues for the flow of electrical charge, water, and contaminants. To facilitate the siting and design of remediation programs, a need exists to map anisotropic distribution of such pathways within glacial tills by determining the azimuth of the dominant joint set. The azimuthal survey method uses standard resistivity equipment with a Wenner array rotated about a fixed center point at selected degree intervals that yields an apparent resistivity ellipse. From this ellipse, joint set orientation can be determined. Azimuthal surveys were conducted at 21 sites in a 500-km2 (193 mi2) area around Milwaukee, Wisconsin, and more specifically, at sites having more than 30 m (98 ft) of glacial till (to minimize the influence of underlying bedrock joints). The 26 azimuthal surveys revealed a systematic pattern to the trend of the dominant joint set within the tills, which is approximately parallel to ice flow direction during till deposition. The average orientation of the joint set parallel with the ice flow direction is N77??E and N37??E for the Oak Creek and Ozaukee tills, respectively. The mean difference between average direct observation of joint set orientations and average azimuthal resistivity results is 8??, which is one fifth of the difference of ice flow direction between the Ozaukee and Oak Creek tills. The results of this study suggest that the surface azimuthal electrical resistivity survey method used for local in situ studies can be a useful noninvasive method for delineating joint sets within shallow geologic material for regional studies. Copyright ?? 2010 The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Application of the surface azimuthal electrical resistivity survey method to determine patterns of regional joint orientation in glacial tills
Series title:
Environmental Geosciences
DOI:
10.1306/eg.04061010002
Volume
17
Issue:
4
Year Published:
2010
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental Geosciences
First page:
175
Last page:
192