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Regional geoelectrical complexity of the Western Canada Basin from magnetotelluric tensor invariants

Abstract

Magnetotelluric data from 323 sites in the Western Canada Basin have provided impedance tensors from which invariants based on Mohr circle analysis are calculated. From thresholds determined from an initial examination of the data, the invariant responses are used to explore the dimensionalities of subsurface structures. This leads to a classification of the electrical structure of the region with respect to dimensionality wherein zones with sites of similar nature are delineated, and demonstrates that the invariants can be used as a dimensionality indicator to infer regional geoelectrical complexity. It is observed that the dimensionality appears to increase with period and this result is consistent with the response from sounding a zone of increasing areal extent and may indicate more laterally complex structure at depth, but may also be due to fundamental limitations of galvanic distortion analysis.

References

  1. Agarwal, A. K. and J. T. Weaver, Magnetic distortion of the magnetotelluric tensor: a numerical study, Earth Planets Space, 52, 347–353, 2000.

    Article  Google Scholar 

  2. Bahr, K., Geological noise in magnetotelluric data: a classification of distortion types, Phys. Earth Planet. Inter, 66, 24–38, 1991.

    Article  Google Scholar 

  3. Boerner, D. E., J. A. Craven, R. D. Kurtz, G. M. Ross, and F. W. Jones, The Great Falls Tectonic Zone: suture or intracontinental shear zone?, Can. J. Earth Sci., 35, 175–183, 1998.

    Article  Google Scholar 

  4. Boerner, D. E., R. D. Kurtz, J. A. Craven, G. M. Ross, and F. W. Jones, A synthesis of electromagnetic studies in the Lithoprobe Alberta Basin Transect: constraints on Paleoproterozoic indentation tectonics, Can. J. Earth Sci., 37, 1509–1534, 2000.

    Article  Google Scholar 

  5. Craven, J. A., D. E. Boerner, R. D. Kurtz, G. M. Ross, and F. W. Jones, Electrical anisotropy beneath the Western Canada Sedimentary Basin, 2000 (in preparation).

  6. Groom, R. W. and R. C. Bailey, Decomposition of magnetotelluric impedance tensor in the presence of local three-dimensional galvanic distortion, J. Geophys. Res., 94, 1913–1925, 1989.

    Article  Google Scholar 

  7. Lilley, F. E. M., Diagrams for magnetotelluric data, Geophysics, 41, 766–770, 1976.

    Article  Google Scholar 

  8. Lilley, F. E. M., Magnetotelluric analysis using Mohr Circles, Geophysics, 58, 1498–1506, 1993a.

    Article  Google Scholar 

  9. Lilley, F. E. M., Mohr circles in magnetotelluric interpretation (i) simple static shift; (ii) Bahr’s analysis, J. Geomag. Geoelectr, 45, 833–839, 1993b.

    Article  Google Scholar 

  10. Lilley, F. E. M. (Ted), Three-dimensionality of the BC87 magnetotelluric data set studied using Mohr Circles, J. Geomag. Geoelectr, 45, 1107–1113, 1993c.

    Article  Google Scholar 

  11. Weaver, J. T., A. K. Agarwal, and F. E. M. Lilley, Characterization of the magnetotelluric tensor in terms of its invariants, Geophys. J. Int., 141, 321–336, 2000.

    Article  Google Scholar 

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Correspondence to F. W. Jones.

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Jones, F.W., Munro, R.A., Craven, J.A. et al. Regional geoelectrical complexity of the Western Canada Basin from magnetotelluric tensor invariants. Earth Planet Sp 54, 899–905 (2002). https://doi.org/10.1186/BF03352437

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Keywords

  • Canada Basin
  • Tensor Element
  • Invariant Response
  • Magnetotelluric Data
  • Mohr Circle