REGIONAL-SCALE MAGNETOTELLURIC SURVEY OF THE YELLOWKNIFE FAULT

Xavier Garcia, Alan G. Jones
Geological Survey of Canada
615 Booth St., Ottawa, Ontario, K1A 0E9, Canada
garcia@cg.NRCan.gc.ca    

During the 1996 Lithoprobe magnetotelluric, MT, survey measurements 
were made at sites from west of Yellowknife -Northwest Territories, 
Canada- across the Yellowknife fault to the east. The 2D 
interpretation of this profile showed the most anomalous response at 
the site located north of Yellowknife virtually on the Yellowknife 
fault. We undertook two other profiles across the fault as part of an 
initiative to extend knowledge of the gold mines in the area.  The 
first MT study carried out during winter 2000 was located 10 km north 
of the previous profile, on a profile extending 20 km with variable 
station spacing from the Yellowknife fault. The main objective of this 
study is the study of the Yellowknife fault as a regional feature and 
the possible relation of the enhanced conductivity with the gold 
deposits.  The second MT study realized in the area consisted of two 
short AMT profiles located south of the city of Yellowknife, close to 
the Kamex islands. The first profile consists on 8 stations and is 
located over a shear zone that contains a gold deposit. The second one 
consists on 5 stations and is located south of the first profile over 
the same shear zone where no mineral has been found. Different 
geophysical studies realized in the area failed to locate the mineral 
deposit. The main objective of this study is whether the MT method is 
valid to locate gold deposits in the Yellowknife area and an 
understanding of this shear zone and its relation with the Yellowknife 
fault.  In this work we present the 2D modeling of these three 
profiles, and come to conclusions regarding the 3D nature of the 
Yellowknife fault, which may have controlled ore deposition.