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Determination of near-surface, crustal and lithospheric structures in the Canadian Precambrian Shield using time-domain electromagnetic and magnetotelluric methods

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dc.contributor.author Wu, Xianghong en_US
dc.date.accessioned 2007-05-22T15:11:05Z
dc.date.available 2007-05-22T15:11:05Z
dc.date.issued 2001-08-01T00:00:00Z en_US
dc.identifier.uri http://hdl.handle.net/1993/1961
dc.description.abstract Two electromagnetic methods were used to analyse the geoelectric structure of the subsurface of regions of the Precambrian Shield in Canada: the magnetotelluric (MT) and time-domain electromagnetic (TEM) methods. Magnetotelluric soundings were made at 60 sites in the southwestern Northwest Territories, Canada, along the LITHOPROBE SNORCLE Transect Corridor 1 and 1A, in the summer of 1996. The sites are located in southwestern Northwest Territories, Canada, between latitudes 60-65N and longitudes 110-125W, and cross the Archean Slave Province, the Proterozoic Buffalo Head, Great Bear Magmatic Arc, Hottah, Fort Simpson and Nahanni terranes, and the Great Slave Lake Shear Zone. Phanerozoic sedimentary rocks overlie the Proterozoic terranes. The main object of this project is to map the fracture zones and fresh/saline water interface in Precambrian granitic rocks using the surface TEM method. The TEM surveys were completed at Sites B, D, URL and A. A GEONICS PROTEM47 system with a 100 m transmitter loop wasused. The data were collected for receiver offsets ranging from 0-280 m on four sides of transmitter loop. Analysis of the TEM and borehole log data indicates a basic three-layer structure: a thin conductive surface layer, a thick resistive second layer with an embedded conductive layer at some stations, and a conductive bottom layer. The results of this study show the TEM method can be used to investigate the fracture zones and groundwater salinity distribution in the Precambrian granitic rocks and contribute to site investigations for nuclear waste deposit. The TEM study in the Lac du Bonnet Batholith was successful in demonstrating the potential of the TEM methods in mapping groundwater salinity in granitic batholith. The PROTEM47 instrument, in combination with a 100 m transmitter loop, provides a suitable TEM system for mapping the resistivity structure of the Lac du Bonnet batholith down to a depth of 300-400 m. For deeper penetration and more accurate results in areas of fracture zones, other TEM systems with greater transmitter power and/or larger transmitter loops will be required. (Abstract shortened by UMI.) en_US
dc.format.extent 18675344 bytes
dc.format.extent 184 bytes
dc.format.mimetype application/pdf
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dc.language en en_US
dc.language.iso en_US
dc.rights info:eu-repo/semantics/openAccess
dc.title Determination of near-surface, crustal and lithospheric structures in the Canadian Precambrian Shield using time-domain electromagnetic and magnetotelluric methods en_US
dc.type info:eu-repo/semantics/doctoralThesis
dc.type doctoral thesis en_US
dc.degree.discipline Geological Sciences en_US
dc.degree.level Doctor of Philosophy (Ph.D.) en_US


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