<  Back to the Polytechnique Montréal portal

Analysis of magnetotelluric data along the Lithoprobe seismic line 21 in the Blake River Group, Abitibi, Canada

Benoit Tournerie and Michel Chouteau

Article (2002)

[img]
Preview
Published Version
Terms of Use: Creative Commons Attribution.
Download (911kB)
Cite this document: Tournerie, B. & Chouteau, M. (2002). Analysis of magnetotelluric data along the Lithoprobe seismic line 21 in the Blake River Group, Abitibi, Canada. Earth, Planets and Space, 54(5), p. 575-589. doi:10.1186/bf03353046
Show abstract Hide abstract

Abstract

Magnetotelluric sounding data have been collected along the Lithoprobe seismic line 21 as a complement to seismic reflection in order to better constrain the structure of the Blake River Group and of the underlying crust. The presence of shallow conductive heterogeneities in an otherwise highly resistive environment typical of the Canadian Shield generates large galvanic distortion that affects the estimates of the impedance tensor. Distortion analysis and tensor decomposition techniques show that MT data support a model represented by a 2D regional model over a 2D deep structure with two different strikes direction and distorted by shallow heterogeneities. The residual static shift affecting each mode for each sounding site is determined using a combination of techniques: shifting the apparent resistivity curves to a reference curve obtained by the authors in the region using 100 km long dipoles, a shallow resistivity estimate using TDEM sounding, 2D minimum structure inversion with free static shift factors. The resulting model does not satisfy both TE and TM modes. A better fit is found by trial and error using a 2D anisotropic model. The Blake River Group is represented as an highly anisotropic resistive layer with a possible decrease in thickness from northwest to southeast. The middle crust is moderately conductive and isotropic, The lower crust and upper mantle is found to be anisotropic and conductive. The geometry of the Blake River Group obtained from the MT data is in agreement with previous gravity and seismic studies.

Uncontrolled Keywords

Earth Sciences; general; Geology; Geophysics/Geodesy

Open Access document in PolyPublie
Subjects: 1000 Génie civil > 1000 Génie civil
4300 Géophysique > 4302 Séismologie
Department: Département des génies civil, géologique et des mines
Research Center: Non applicable
Date Deposited: 06 Nov 2018 13:25
Last Modified: 07 Nov 2018 01:20
PolyPublie URL: https://publications.polymtl.ca/3376/
Document issued by the official publisher
Journal Title: Earth, Planets and Space (vol. 54, no. 5)
Publisher: SpringerOpen
Official URL: https://doi.org/10.1186/bf03353046

Statistics

Total downloads

Downloads per month in the last year

Origin of downloads

Dimensions

Repository Staff Only