Interpretation of the Western Ultra Deep Levels 3-D seismic survey

Gibson, Mark A. S.; Jolley, Stephen J.; Barnicoat, A. C.

doi:10.1190/1.1438704

Cited by 22 publications

(26 citation statements)

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“…Reflection seismic methods were implemented in the 1980s, rejuvenating exploration activities and contributing to the discovery of the South Deep orebody (Haslett, 1994) and new resources in the Bothaville Gap Tucker et al, 1994). The adaptation of reflection seismic technology to the hard-rock environment over the last quarter century has been described by several authors, e.g., Campbell and Peace (1984), Durrheim (1986), Pretorius et al (1989), Campbell (1990), Campbell and Crotty (1990), ), Campbell (1994), De Wet and Hall (1994, Pretorius et al (1994), Weder (1994), Pretorius and Trewick (1997), Gibson et al (2000), Stuart et al (2000), Pretorius et al (2000), and Gillot et al (2005). A comprehensive review of the use of reflection seismology to map the Witwatersrand Basin is provided by Pretorius et al (2003).…”

Section: Africamentioning

confidence: 99%

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

et al. 2012

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Due to high metal prices and increased difficulties in finding shallower deposits, the exploration for and exploitation of mineral resources is expected to move to greater depths. Consequently, seismic methods will become a more important tool to help unravel structures hosting mineral deposits at great depth for mine planning and exploration. These methods also can be used with varying degrees of success to directly target mineral deposits at depth. We review important contributions that have been made in developing these techniques for the mining industry with focus on four main regions: Australia, Europe, Canada, and South Africa. A wide range of case studies are covered, including some that are published in the special issue accompanying this article, from surface to borehole seismic methods, as well as petrophysical data and seismic modeling of mineral deposits. At present, high-resolution 2D surveys mostly are performed in mining areas, but there is a general increasing trend in the use of 3D seismic methods, especially in mature mining camps.

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Section: Africamentioning

confidence: 99%

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

et al. 2012

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“…The fault forms a subvertical zone and extends from about 1 km to at least 5 km below the surface and is exposed in the TauTona mine at a depth of 3.6 km, and Mponeng mine at depth of 2.8 km (GIBSON et al, 2000a). Underground mapping suggests that the Pretorius fault is an oblique right-lateral fault with horizontal displacement of about 200 m and vertical displacement, south side thrown up, up to 100 m (D. KERSHAW, personal communication, 2005) and up to 30 m at the NELSAM site.…”

Section: The Pretorius Faultmentioning

confidence: 99%

“…8). GIBSON et al (2000a) suggested that the Pretorius fault was reactivated by gravitational collapse and extension during the Platberg rifting and/or the Vredefort impact. The features in Fig.…”

Section: Cataclasite-bearing Segmentsmentioning

confidence: 99%

Earthquake Rupture at Focal Depth, Part I: Structure and Rupture of the Pretorius Fault, TauTona Mine, South Africa

Heesakkers

Murphy

Reches

2011

Pure Appl. Geophys.

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We analyze the structure of the Archaean Pretorius fault in TauTona mine, South Africa, as well as the rupture-zone that recently reactivated it. The analysis is part of the Natural Earthquake Laboratory in South African Mines (NELSAM) project that utilizes the access to 3.6 km depth provided by the mining operations. The Pretorius fault is a *10 km long, oblique-strikeslip fault with displacement of up to 200 m that crosscuts fine to very coarse grain quartzitic rocks in TauTona mine. We identify here three structural zones within the fault-zone: (1) an outer damage zone, *100 m wide, of brittle deformation manifested by multiple, widely spaced fractures and faults with slip up to 3 m; (2) an inner damage zone, 25-30 m wide, with high density of anastomosing conjugate sets of fault segments and fractures, many of which carry cataclasite zones; and (3) a dominant segment, with a cataclasite zone up to 50 cm thick that accommodated most of the Archaean slip of the Pretorius fault, and is regarded as the 'principal slip zone' (PSZ). This fault-zone structure indicates that during its Archaean activity, the Pretorius fault entered the mature fault stage in which many slip events were localized along a single, PSZ. The mining operations continuously induce earthquakes, including the 2004, M2.2 event that rejuvenated the Pretorius fault in the NELSAM project area. Our analysis of the M2.2 rupture-zone shows that (1) slip occurred exclusively along four, pre-existing large, quasi-planer segments of the ancient fault-zone; (2) the slipping segments contain brittle cataclasite zones up to 0.5 m thick; (3) these segments are not parallel to each other; (4) gouge zones, 1-5 mm thick, composed of white 'rock-flour' formed almost exclusively along the cataclasite-host rock contacts of the slipping segments; (5) locally, new, fresh fractures branched from the slipping segments and propagated in mixed shear-tensile mode; (6) the maximum observed shear displacement is 25 mm in oblique-normal slip. The mechanical analysis of this rupture-zone is presented in Part II (HEESAKKERS et al.,

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“…The geology and structural setting of the Witwatersrand basin is documented by many authors, including Coward et al (1995), Gibson et al (2000), Jolley et al (2004), Beach and Smith (2007), and Dankert and Hein (2010). In summary, the Witwatersrand Supergroup unconformably overlies the Dominion Group.…”

Section: Geologic Settingmentioning

confidence: 89%

“…However, there are many fault traces that can be confidently projected from the VCR to the BLR horizons. These may represent faults that were reactivated during the post-BLR deformation event described by Coward et al (1995), Gibson et al (2000), and Dankert and Hein (2010). According to D' Agostino et al (1998) and Jackson et al (2006), many structures in extensional basins are reactivated during later deformational events.…”

Section: Fault Mappingmentioning

confidence: 90%

3D edge detection seismic attributes used to map potential conduits for water and methane in deep gold mines in the Witwatersrand basin, South Africa

et al. 2012

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Inrushes of ground water and the ignition of flammable gases pose risks to workers in deep South African gold mines. Large volumes of water may be stored in solution cavities in dolomitic rocks that overlie the Black Reef (BLR) Formation, while there are several possible sources for methane, namely, coal seams, kerogen found in some gold ore bodies, or methane introduced by igneous intrusions. Potential conduits that may transport water and methane to underground workings were mapped using 3D reflection seismic data. Edge detection attributes successfully identified many faults, some with displacements as small as 10 m. Faults that displace the Ventersdorp Contact Reef (VCR) and the BLR horizons were of special interest, as known occurrences of fissure water and methane in underground workings show a good correlation with faults that were imaged on the VCR and BLR horizons. Because there are uncertainties in determining the linkage of faults with aquifers and methane sources, it is considered prudent to assume that all structures that displace the VCR and BLR horizons are potential conduits.

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Interpretation of the Western Ultra Deep Levels 3-D seismic survey

Cited by 22 publications

References 0 publications

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

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

Earthquake Rupture at Focal Depth, Part I: Structure and Rupture of the Pretorius Fault, TauTona Mine, South Africa

3D edge detection seismic attributes used to map potential conduits for water and methane in deep gold mines in the Witwatersrand basin, South Africa

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