A4 Article in conference proceedings
3D traveltime tomography and reflection imaging for mine planning and exploration in the Kevitsa Ni-Cu-PGE Mine, Finland




List of Authors: Alireza Malehmir, Ari Tryggvason, Chris Wijns, Teemu Lindqvist, Pietari Skyttä, Emilia Anna-Liisa Koivisto, Markku Montonen
Publisher: European Association of Geoscientists and Engineers, EAGE
Publication year: 2016
Book title *: The Techcnical Programme for the 22nd European Meeting of Environmental and Engineering Geophysics: First Conference on Geophysics for Mineral Exploration and Mining
Journal name in source: 1st Conference on Geophysics for Mineral Exploration and Mining, Near Surface Geoscience 2016
ISSN: 2214-4609

Abstract

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.


Last updated on 2019-29-01 at 22:46