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Electromagnetic images of regional structure in the southern Canadian Cordillera
Author(s) -
Jones Alan G.,
Gough D. Ian,
Kurtz Ron D.,
DeLaurier Jon M.,
Boerner David E.,
Craven James A.,
Ellis Rob G.,
McNeice Gary W.
Publication year - 1992
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/92gl01457
Subject(s) - magnetotellurics , geology , foreland basin , transect , crust , basement , seismology , geomorphology , paleontology , tectonics , oceanography , electrical resistivity and conductivity , geography , archaeology , electrical engineering , engineering
As part of Lithoprobe's Southern Cordilleran transect investigations, magnetotelluric (MT) soundings were made at 160 sites providing unprecedented coverage from the Rockies to the west coast. Striking lateral variation, which spatially correlates with the morphogeological belt boundaries, is apparent at periods sensing the lower crust (≈10 s). For the Rockies, MT phases are around 35°, indicative of a moderately resistive (100's – 1000's Ω·m) North American Basement. Foreland belt phases are transitional and increase from 60° in the east to 70° in the west. Omineca and Coast belt phases are high (75°), implying a conductive (10–30 Ω·m) lower crust, whereas Intermontane belt phases are more than 10° lower (equivalent to ≈150 Ω·m). The regional variation in conductivity correlates to first order with surface heat flow changes along the profile and is also correlative with coincident seismic reflection sections in some aspects.