1887

Abstract

Summary

Kevitsa disseminated Ni-Cu-PGE deposit in northern Finland is hosted by a major high velocity (6000–7500 m/s) gabbroic intrusion. The deposit is currently being mined using open-pit mining method at already over 100 m depth, and the final pit will extend to about 400–500 m depth in about 20 years, hence justifying a 3D seismic survey for its careful planning. The 3D seismic survey was carried out in 2010, before mining activities commenced, and resulted in a reflection volume rich in reflectivity, however, poor near the surface likely due to the survey setup and extremely high bedrock velocities. 3D first break tomography was performed with the main objective of linking near-surface geological information with the reflection seismic volume allowing to find a major low-velocity linear zone in the bedrock within the first 50 m depth. This was associated with a gently-dipping reflector with the same strike at 150 m depth and extending to about 500 m depth. The low-velocity zone striking in NE-SW, and originating from a gently-dipping fracture system, may contribute towards the formation of wedge blocks within the northern side of the planned open pit, which can be critical for its stability in the near future.

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/content/papers/10.3997/2214-4609.201602126
2016-09-04
2024-04-25
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References

  1. Lindqvist, T.
    [2014] 3D characterization of brittle fracture zones in Kevitsa open pit excavation, northern Finland. MSC thesis, University of Helsinki, Finland, 87 p.
    [Google Scholar]
  2. Koivisto, E., Malehmir, A., Hellqvist, N., Voipio, T. and Wijns, C.
    [2015] Building a 3D model of lithological contacts and near-mine structures in the Kevitsa mining and exploration site, northern Finland: constraints from 2D and 3D reflection seismic data. Geophysical Prospecting, 63, 754–773.
    [Google Scholar]
  3. Koivisto, E., Malehmir, A., Heikkinen, P., Heinonen, S. and Kukkonen, I.
    [2012] 2D reflection seismic investigations in the Kevitsa Ni-Cu-PGE deposit, northern Finland. Geophysics, 77, WC149–WC162.
    [Google Scholar]
  4. Kukkonen, I., Lahti, I., Heikkinen, P., and HIRE Working Group of the Geological Survey of Finland
    [2009] HIRE Seismic Reflection Survey in the Kevitsa Ni-PGE deposit, North Finland. GTK Report Q 23/2008/59, 38 pp.
    [Google Scholar]
  5. Malehmir, A., Juhlin, C., Wijns, C., Urosevic, M., Valasti, P. and Koivisto, E.
    [2012] 3D reflection seismic investigation for open-pit mine planning and exploration in the Kevitsa Ni-Cu-PGE deposit, Northern Finland. Geophysics, 77, WC95–WC108.
    [Google Scholar]
  6. Malehmir, A., Koivisto, E., Manzi, M., Cheraghi, S., Durrheim, R., Bellefleur, G., Wijns, C., Hein, K. and King, N.
    [2014] A review of reflection seismic investigations in three major metallogenic regions: the Kevitsa Ni-Cu-PGE district (Finland), Witwatersrand goldfields (South Africa), and the Bathurst Mining Camp (Canada). Ore Geology Reviews, 56, 423–441.
    [Google Scholar]
  7. Tryggvason, A., Rögnvaldsson, S. Th. and Flóvenz, Ó.G.
    [2002] Three-dimensional imaging of the P-and S-wave velocity structure and earthquake locations beneath Southwest Iceland. Geophys. J. Int., 151, 848–866.
    [Google Scholar]
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