Geoelectric structure of the Great Slave Lake shear zone in northwest Alberta: implications for structure and tectonic history

The study of ancient plate boundaries can provide insights into the past and present-day tectonic processes. Here, we describe a magnetotellurics (MT) study of the Precambrian basement of the Hay River Fault (HRF) in northwest Alberta, which is the southwest segment of the Great Slave Lake shear zon...

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Bibliographic Details
Published in:Canadian Journal of Earth Sciences
Main Authors: Wang, Enci, Unsworth, Martyn, Chacko, Thomas
Format: Article in Journal/Newspaper
Language:English
Published: Canadian Science Publishing 2018
Subjects:
General Earth and Planetary Sciences
Canada
Great Slave Lake
Hay River
Buffalo Head
Kiskatinaw
Ksituan
Slave Lake
Online Access:http://dx.doi.org/10.1139/cjes-2017-0067
http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjes-2017-0067
http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2017-0067
Description
Summary:The study of ancient plate boundaries can provide insights into the past and present-day tectonic processes. Here, we describe a magnetotellurics (MT) study of the Precambrian basement of the Hay River Fault (HRF) in northwest Alberta, which is the southwest segment of the Great Slave Lake shear zone. New broadband MT data were collected to give a clearer image of the crustal structure. The Western Canada Sedimentary Basin was imaged as a low-resistivity layer above the resistive crystalline basement. Four basement conductors were defined, and correlate with the terrane boundaries delineated with aeromagnetic data. These are (1) a major conductor in the Kiskatinaw domain, (2) a conductor on the boundary of the Ksituan and Chinchaga domains, (3) a conductor on the boundary of the Chinchaga and Buffalo Head domains, and (4) a conductor near the HRF. Both (1) and (2) correspond to areas of high seismic reflectivity. The low resistivity can be explained by interconnected grain boundary graphite or sulfide phases deposited by metamorphic fluid migration. The HRF was not definitively located in previous studies. The new data show that the HRF could be thin (1 km) or wide (10 km) and located at the boundary of the contrasting aeromagnetic anomalies or further to the north. Various tectonic processes are proposed to interpret the possible locations of the HRF. No electrical anisotropy structure is required to interpret the MT data in this study.

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