9. Seismic Imaging of Precious and Base-Metal Deposits in Southern Africa

Abstract

Reflection seismology has been widely used to explore for gold, platinum, and base-metal deposits in southern Africa, and for mine planning purposes. The geological structure of the Witwatersrand basin has been mapped, enabling areas where gold-bearing reefs occur at mineable depths to be identified. Within the Bushveld Complex, seismic stratigraphic techniques have been used to distinguish areas of "pothole" reef, that may present mining difficulties, from areas of "normal" platinum-bearing Merensky Reef. The mine-seismicprofiling (MSP) method, which makes use of sensors deployed in boreholes drilled from mine workings, has been developed to delineate structures that are too small to be detected from the surface but may present mining problems. Reflection seismology has also been used to explore for base metal deposits associated with buried paleokarst features in northern Namibia. Lastly, reflection seismology has been used to map the downdip extension of massive sulfide "shoots" at Otjihase Mine in the Matchless Amphibolite Belt of Namibia.

Seismic methods in mineral exploration and mine planning: A general overview of past and present case histories and a look into the future

“…Outside South Africa, Gold Fields conducted a series of reflection seismic surveys in Namibia in support of their exploration and mining activities (Stevenson et al, 2003). One survey was conducted to search for Pb-Cu-Zn ore bodies, where mineralization is controlled by a pipelike paleokarst structure in a moderately folded dolomitic succession.…”

“…It clearly shows the potential of reflection seismic methods for imaging of large-scale structures hosting the mineralization in the area, e.g., the UG2 layer. The application of 2D and 3D reflection seismics in the Bushveld Complex has been described in the literature and reports (Campbell, 1990;Durrheim and Maccelari, 1991;Odgers et al, 1993;Davison and Chunnett, 1999;Larroque et al, 2002;Stevenson et al, 2003;Trickett et al, 2005Trickett et al, , 2007Trickett et al, , 2009. A comprehensive review is published by Campbell (2011).…”

“…The Deep Mine research program (Durrheim, 2007) sought to develop technologies to map reef displacements exceeding 2 m within 200 m of mining. A technology scan indicated that borehole radar and mine seismic profiling (MSP) stood the greatest chances of success (Stevenson et al, 2003). MSP is essentially the application of VSP techniques applied underground in boreholes with arbitrary orientations, including upholes.…”

3D reflection seismic imaging for open-pit mine planning and deep exploration in the Kevitsa Ni-Cu-PGE deposit, northern Finland

“…Although a series of studies are currently being conducted, there are not many published accounts on the use of 3D reflection seismic methods for the purpose of deep mine planning in the crystalline environment, especially in Europe. Three-dimensional reflection seismic methods have been used in South Africa with encouraging results, allowing imaging of fault systems that in turn control the geometry of the ore horizon (Pretorius et al, 2003;Stevenson et al, 2003). To our knowledge, there is no 3D reflection seismic survey conducted for deep open-pit mine planning.…”

3D reflection seismic investigation for mine planning and exploration in the Kevitsa Ni‐Cu‐PGE deposit, northern Finland

“…There are not many published accounts of the use of 3D reflection seismic methods in mine planning in the crystalline environment, especially in Europe. 3D reflection seismic methods have been used in South Africa with encouraging results, allowing imaging of fault systems that in turn control the geometry of the ore horizon (Stevenson et al, 2003). Nevertheless, 3D reflection seismic surveys have been used for the exploration of deep-seated deposits with several examples from Canada and Australia (e.g., Milkereit et al, 2000;Adam et al, 2003;Malehmir and Bellefleur, 2009;Harrison and Urosevic, 2009).…”