Open AccessA magnetotelluric survey on Manitoulin Island and Bruce Peninsula along GLIMPCE seismic line J: black shales mask the Grenville Front
Author(s) -
Mareschal M.,
Kurtz R. D.,
Chouteau M.,
Chakridi R.
Publication year - 1991
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1991.tb03453.x
Subject(s) - magnetotellurics , geology , phanerozoic , peninsula , seismology , tectonics , front (military) , paleontology , geophysics , structural basin , electrical resistivity and conductivity , oceanography , archaeology , cenozoic , electrical engineering , history , engineering
SUMMARY The results of a magnetotelluric survey extending southeast from Manitoulin Island to Bruce Peninsula across the Grenville Front Tectonic Zone are presented. A cover of Phanerozoic sediments, including a highly conductive layer of black shales of limited extent, precludes the exact definition of electrical features at depth; thus a comparison with the seismic reflections observed on GLIMPCE line J is impossible. However, the interpretation of the electromagnetic data proves to be an excellent illustration of electrical distortion and attenuation in 3‐D environments. We show in particular that features originally interpreted as due to a thin conductor at mid‐crustal depth are actually representative of edge effects related to the sedimentary cover. A schematic 2‐D model of the region along selected profiles including the Phanerozoic sediments also helps to reconciliate electromagnetic observations at East Bull Lake (Krutz, Ostrowski & Niblett 1986) with those of the present survey.