1887

Abstract

Summary

A combination of audiomagnetotelluric (AMT) ground and borehole measurements can be expected to reduce the ambiguity in models of electrical resistivity as compared to models computed from ground data. We consider a synthetic 2-D model with a dipping mineralisation zone of ~ 1 Ohmm resistivity and 1.5 km depth extent embedded in a resistive host of 10000 Ohmm underneath weathered overburden of 100 Ohmm. 2-D inversion models derived from combinations of surface impedance measurements and borehole measurements in the form of horizontal magnetic transfer functions and vertical magnetic and electric transfer functions are compared. We observed that combinations of ground and borehole AMT measurements yield inversion models that have better pronounced resistivity contrasts at depth than models computed exclusively from surface measurements. To record the types of borehole AMT data suggested by us, 3-component borehole magnetometers sufficiently sensitive to the AMT magnetic field need to be developed. A miniaturised 3-component SQUID magnetometer may be a promising solution.

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/content/papers/10.3997/2214-4609.201602103
2016-09-04
2024-03-29
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References

  1. Chouteau, M., Zhang, P., Dion, D.J., Giroux, B., Morin, R. and Krivochieva, S.
    [1997] Delineating mineralization and imaging the regional structure with magnetotellurics in the region of Chibougamau (Canada). Geophysics, 62(3), 730–748.
    [Google Scholar]
  2. Garcia Juanatey, M.d.l.A., Hübert, J., Tryggvason, A. and Pedersen, L.B.
    [2013a] Imaging the Kristineberg mining area with two perpendicular magnetotelluric profiles in the Skellefte Ore District, northern Sweden. Geophys. Prospect., 61(1), 200–219.
    [Google Scholar]
  3. Garcia Juanatey, M.d.l.A., Tryggvason, A., Juhlin, C., Bergström, U., Hübert, J. and Pedersen, L.B.
    [2013b] MT and reflection seismics in northwestern Skellefte Ore District, Sweden. Geophysics, 78(2), B65–B76.
    [Google Scholar]
  4. Hübert, J., Garcia Juanatey, M.d.l.A., Malehmir, A., Tryggvason, A. and Pedersen, L.B.
    [2013] The upper crustal 3-D resistivity structure of the Kristineberg area, Skellefte district, northern Sweden revealed by magnetotelluric data. Geophys. J. Int., 192(2), 500–513.
    [Google Scholar]
  5. Jones, A.G.
    [1983] A passive natural-source twin-purpose borehole technique vertical gradient magnetometry (VGM). J. Geomagn. Geoelectr., 35(11–12), 473–490.
    [Google Scholar]
  6. Jones, A.G. and Garcia, X.
    [2003] Okak Bay AMT data-set case study: Lessons in dimensionality and scale. Geophysics, 68(1), 70–91.
    [Google Scholar]
  7. Kalscheuer, T., Garcia Juanatey, M.d.l.A., Meqbel, N. and Pedersen, L.B.
    [2010] Non-linear model error and resolution properties from two-dimensional single and joint inversions of direct current resistivity and radiomagnetotelluric data. Geophys. J. Int., 182(3), 1174–1188.
    [Google Scholar]
  8. Livelybrooks, D., Mareschal, M., Blais, E. and Smith, J.T.
    [1996] Magnetotelluric delineation of the Trillabelle massive sulfide body in Sudbury, Ontario. Geophysics, 61(4), 971–986.
    [Google Scholar]
  9. Sasaki, Y., Yoneda, Y. and Matsuo, K.
    [1992] Resistivity imaging of controlled-source audiofrequency magnetotelluric data. Geophysics, 57(7), 952–955.
    [Google Scholar]
  10. Schmucker, U., Spitzer, K. and Steveling, E.
    [2009] An electromagnetic sounding experiment in Germany using the vertical gradient of geomagnetic variations observed in a deep borehole. Geophys. J. Int., 178(3), 1273–1288.
    [Google Scholar]
  11. West, R.C. and Ward, S.H.
    [1988] The borehole controlled-source audiomagnetotelluric response of a three-dimensional fracture zone. Geophysics, 53(2), 215–230.
    [Google Scholar]
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