Special Issue: Electromagnetic Induction in the Earth
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Analysis of magnetotelluric data along the Lithoprobe seismic line 21 in the Blake River Group, Abitibi, Canada
Earth, Planets and Space volume 54, pages 575–589 (2002)
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.
References
Adam, E., B. Milkereit, M. Mareschal, A. E. Barnes, C. Hubert, and M. Salisbury, The application of reflection seismology to the investigation of the geometry of near-surface units and faults in the Blake River Group, Abitibi belt, Quebec, Canadian Journal of Earth Sciences, 29, 2038–2045, 1992.
Bahr, K., Interpretation of the magnetotelluric impedance tensor: regional induction and local telluric distortion, J. Geophys., 62, 119–127, 1988.
Bahr, K., Geologic noise in magnetotelluric data: a classification of distortion types, Phys. Earth Planet. Inter., 66, 24–38, 1991.
Bellefleur, G., Contribution of potential methods to the geological and the deep structure cartography in the Blake River Group, Abitibi, Master’s thesis, École Polytechnique de Montréal, 101 pp., 1992 (in French).
Bitri, A., J. P. Brun, J. Chantraine, P. Guennoc, G. Marquis, J. M. Marthelot, J. Perrin, F. Pivot, B. Tournerie, and C. Truffert, Crustal structure of the Cadomian block in the north Brittany (France): seismic reflection and magnetotelluric sounding (Geofrance 3D—Armor project), Comptes Rendus de l’Academie des Sciences de Paris, 325, 171–177, 1997 (in French).
Camiré, G. and D. H. Watkinson, Volcanic stratigraphy and structure in the Hunter-Creek fault area, Rouyn-Noranda, Quebec, Canadian Journal of Earth Sciences, 27, 1348–1358, 1990.
Chakridi, R., Magnetotelluric interpretation in complex environments, Ph.D. thesis, Ecole Polytechnique de Montréal, 253 pp., 1991 (in French).
Chown, E. H., R. Daigneault, and W. Mueller, Tectonic evolution of the Northern Volcanic Zone, Abitibi belt, Quebec, Canadian Journal of Earth Sciences, 29, 2211–2225, 1992.
Clowes, R. M., A. J. Calvert, D. W. Eaton, Z. Hajnal, J. Hall, and G. M. Ross, Lithoprobe reflection studies of Archean and Proterozoic crust in Canada, Tectonophys., 264, 65–88, 1996.
Cook, F. A. and A. G. Jones, Seismic reflections and electrical conductivity: A case of Holmes’ curious dog?, Geology, 23, 141–144, 1995.
Deschamps, F., M. Chouteau, and D. J. Dion, Geological interpretation of aeromagnetic and gravimetric data in the region located at the west part of the Rouyn-Noranda city, in Etudes geophysiques recentes de certains secteurs de la ceinture volcanosedimentaire de l’Abitibi, edited by D.-J. Dion, Ministère des Ressources Naturelles, Québec, DV-93-10, 55 pp., 1993 (in French).
Dumas, I., Interpretation of line 21 seismic reflection data, Blake River Group, Abitibi (Canada), Master’s thesis, École Polytechnique de Montréal, 111 pp., 1995 (in French).
Eisel, M. and K. Bahr, Electrical anisotropy in the lower crust of British Columbia: an interpretation of a magnetotelluric profile after tensor decomposition, J. Geomag. Geoelectr., 45, 1115–1126, 1993.
Gamble, T. D., W. M. Goubau, and J. Clarke, Magnetotellurics with a remote magnetic reference, Geophysics, 44, 53–68, 1979.
Gough, D. I., Seismic reflectors, conductivity, water and stress in the continental crust, Nature, 323, 143–144, 1986.
Green, A. G., B. Milkereit, L. J. Mayrand, J. N. Ludden, C. Hubert, S. J. Jackson, R. H. Sutcliffe, G. F. West, P. Verpaelst, and A. Simard, Deep structure of an Archean greenstone terrane, Nature, 344, 327–330, 1990.
Groom, R. W. and R. C. Bailey, Decomposition of magnetotelluric impedance tensors in the presence of local three-dimensional galvanic distortion, J. Geophys. Res., 94, 1913–1925, 1989.
Groom, R. W., R. D. Kurtz, A. G. Jones, and D. E. Boerner, A quantitative methodology to extract regional magnetotelluric impedances and determine the dimension of the conductivity structure, Geophysical Journal International, 115, 1095–1118, 1993.
Hobbs, B. A., Terminology and symbols for use in studies of electromagnetic induction in the Earth, Surveys in Geophysics, 13, 489–515, 1992.
Hubert, C., P. Trudel, and L. Gelinas, Archean wrench fault tectonics and structural evolution of the Blake River Group, Abitibi belt, Quebec, Canadian Journal of Earth Sciences, 21, 1024–1032, 1984.
Jackson, S. L. and A. R. Cruden, Formation of the Abitibi greenstone belt by arc-trench migration, Geology, 23, 471–474, 1995.
Jackson, S. L., R. H. Sutcliffe, J. N. Ludden, C. Hubert, A. G. Green, B. Milkereit, L. J. Mayrand, G. F. West, and P. Verpaelst, Southern Abitibi greenstone belt: Archean crustal structure from seismic-reflection profiles, Geology, 18, 1086–1090, 1990.
Jones, A. G., MT and reflection: an essential combination, Geophys. J. Roy. Astr. Soc., 89, 7–18, 1987.
Jones, A. G., Static shift of magnetotelluric data and its removal in sedimentary basin environment, Geophysics, 53, 967–978, 1988.
Jones, A. G. and R. W. Groom, Strike-angle determination from the magnetotelluric impedance tensor in the presence of noise and local distortion: Rotate at your peril!, Geophysical Journal International, 113, 524–534, 1993.
Jones, A. G., R. W. Groom, and R. D. Kurtz, Decomposition and modelling of the BC87 dataset J. Geomag. Geoelectr., 45, 1127–1150, 1993.
Kellett, R. L., M. Chouteau, R. D. Kurtz, and M. Mareschal, A magnetotelluric transect from the Grenville to the Northern Abitibi, Lithoprobe Report, 25, 55–58, 1992a.
Kellett, R. L., M. Mareschal, and R. D. Kurtz, A model of lower crustal electrical anisotropy for the Pontiac Subprovince of the Canadian Shield, Geophysical Journal International, 111, 141–150, 1992b.
Kellett, R. L., A. E. Barnes, and M. Rive, The deep structure of the Grenville Front: a new perspective from western Quebec, Canadian Journal of Earth Sciences, 31, 282–292, 1994.
Kurtz, R. D., M. Mareschal, F. Richard, R. L. Kellett, and R. Bailey, Crustal structure from magnetotelluric soundings along a profile from the Kapuskasing zone to the Pontiac Subprovince, Lithoprobe Report, 25, 59–63, 1992.
Kurtz, R. D., J. A. Craven, E. R. Niblett, and R. A. Stevens, The conductivity of the crust and mantle beneath the Kapuskasing Uplift: electrical anisotropy in the upper mantle, Geophysical Journal International, 113, 483–498, 1993.
Ludden, J. N., C. Hubert, and C. Gariépy, The tectonic evolution of the Abitibi greenstone belt of Canada, Geological Magazine, 123, 153–166, 1986.
Mareschal, M., R. L. Kellett, R. D. Kurtz, J. N. Ludden, S. Ji, and R. C. Bailey, Archean cratonic roots, mantle shear zones and deep electrical anisotropy, Nature, 375, 134–137, 1995.
Marquis, G., A. Jones, and R. D. Hyndman, Coincident conductive and reflective middle and lower crust in southern British Columbia, Geophysical Journal International, 120, 111–131, 1995.
MRN, Airborne EM survey using INPUT MK VI, Noranda region, Relevés Géophysiques inc. Ministère des Ressources Naturelles, Québec, DP-86-17, 1986 (in French).
Pek, J. and T. Verner, Finite difference modelling of magnetotelluric fields in 2-D anisotropic media, Geophysical Journal International, 128, 505–521, 1997.
Perron, G. and A. J. Calvert, Shallow, high-resolution seismic imaging at the Ansil mining camp in the Abitibi greenstone belt, Geophysics, 63, 379–391, 1998.
Singer, B. S., Correction for distortions of magnetotelluric fields: Limits of validity of the static approach, Surveys in Geophysics, 13, 309–340, 1992.
Smith, J. T., Understanding telluric distortion matrices, Geophysical Journal International, 122, 219–226, 1995.
Smith, J. T. and J. R. Booker, Rapid inversion of two- and three-dimensional magnetotelluric data, J. Geophys. Res., 96, 3905–3922, 1991.
Tournerie, B. and M. Chouteau, Deep conductivity structure in Abitibi using long dipole magnetotelluric measurements, Geophys. Res. Lett., 25, 2317–2320, 1998.
Verpaelst, P., A. S. Peloquin, E. Adam, A. E. Barnes, J. N. Ludden, D. J. Dion, C. Hubert, B. Milkereit, and M. Labrie, Seismic reflection profiles across the “Mine Series” in the Noranda Camp of the Abitibi belt, eastern Canada, Canadian Journal of Earth Sciences, 32, 167–176, 1995.
Zhang, P., L. B. Pedersen, M. Mareschal, and M. Chouteau, Channeling contribution to tipper vectors: a magnetic equivalent to electrical distortion, Geophysical Journal International, 113, 693–700, 1993.
Zhang, P., M. Chouteau, M. Mareschal, R. Kurtz, and C. Hubert, High-frequency magnetotelluric investigation of crustal structure in northern central Abitibi, Quebec, Canada, Geophysical Journal International, 120, 406–418, 1995.
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Tournerie, B., Chouteau, M. Analysis of magnetotelluric data along the Lithoprobe seismic line 21 in the Blake River Group, Abitibi, Canada. Earth Planet Sp 54, 575–589 (2002). https://doi.org/10.1186/BF03353046
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DOI: https://doi.org/10.1186/BF03353046