A Review of the Witwatersrand Basin - The World’s Greatest Goldfield

Tucker, Rodney F.; Viljoen, R. P.; Viljoen, M. J.

doi:10.18814/epiiugs/2016/v39i2/95771

Cited by 60 publications

(32 citation statements)

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“…Notably, the exposed impact structure is centered within the Witwatersrand gold fields, which extend approximately 400 km in diameter (Tucker et al. ).…”

Section: Geological Settingmentioning

confidence: 99%

“…The initial diameter of the crater is estimated to be up to 300 km based on geophysical modeling (Henkel and Reimold 1998) and structural geology and microstructural constraints (Therriault et al 1997b), although numerical modeling suggested an original diameter of 170-180 km (Ivanov 2005). Notably, the exposed impact structure is centered within the Witwatersrand gold fields, which extend approximately 400 km in diameter (Tucker et al 2016).…”

Section: Geological Settingmentioning

confidence: 99%

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Geophysical characterization of the Daskop granophyre dyke and surrounding host rocks, Vredefort impact structure, South Africa

Fourie

Huber

Kovaleva

2019

Meteorit & Planetary Scien

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Granophyre dykes in the central part of the Vredefort impact structure are believed to be the remnants of the impact melt sheet, which intruded downwards along the fractures in the crater floor. Little is known about their original penetration depth, dip, structural relationships with the host rocks, and their general geophysical characteristics. This information is critical to understand the emplacement history of the granophyre dykes, as it relates to the formation and modification of large impact structures. We conducted magnetic and resistivity surveys across the Daskop granophyre dyke (DGD), one of the impact melt dykes in the structure's core. The magnetic survey revealed that the DGD gives a strong magnetic response at positions where the dyke outcrop exceeds the surface topography, but a very weak response where the outcrop is nearly at the same elevation as the surrounding topography. The magnetic anomaly is thus predominantly due to the outcrop protruding above ground level, suggesting a limited volume of dyke material in the subsurface and a small penetration depth. The resistivity survey performed on two profiles, set perpendicularly across the DGD, indicated a shallow penetration depth (<3 m), consistent with the magnetic interpretation. Thus, our geophysical study demonstrates that the DGD is currently at the very bottom of its original emplacement. This may either be an erosional coincidence, or it may be controlled by a fundamental process of impact cratering. Further studies are warranted to determine if other granophyre dykes at Vredefort are similarly at their lowermost terminations.

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“…Notably, the exposed impact structure is centered within the Witwatersrand gold fields, which extend approximately 400 km in diameter (Tucker et al. ).…”

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Geophysical characterization of the Daskop granophyre dyke and surrounding host rocks, Vredefort impact structure, South Africa

Fourie

Huber

Kovaleva

2019

Meteorit & Planetary Scien

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“…The Au occurred in association with pyrite, carbon, and uranium, and most of it has been subsequently modified during later hydrothermal activity [36]. Although debate is ongoing as to whether the genesis of the Witwatersrand Au deposits can be attributed to a paleo-placer source or a hydrothermal source, the modified placer process (a combination of the two sources) is thought to be more plausible [40] (Figure 3). The mining target reefs are both the Ventersdorp Contact Reef (VCR) and the Upper Elsburg formation conglomerates [36].…”

Section: Sedimentary Au Deposits (Witwatersrand Au Fields)mentioning

confidence: 99%

Invisible Gold in Pyrite from Epithermal, Banded-Iron-Formation-Hosted, and Sedimentary Gold Deposits: Evidence of Hydrothermal Influence

et al. 2019

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“Invisible gold” in pyrite is defined as an Au solid solution of the pyrite lattice, sub-microscopic Au nanoparticles (NPs) in the pyrite, or other chemisorption complexes of Au. Because the relationship between the Au and As concentrations in pyrite could indicate the genesis of the deposit, the purpose of this study is to assess the micro-analytical characteristics of the Au–As relationship in pyrite from epithermal and hydrothermally affected sedimentary Au deposits by secondary ion mass spectrometry. The Au and As concentrations in pyrite vary from 0.04 to 30 ppm and from 1 to 1000 ppm, respectively, in the high-sulfidation Nansatsu-type epithermal deposits; these concentrations are both lower than those of the low-sulfidation epithermal Hishikari deposit. The Au concentrations in pyrrhotite and pyrite reach 6 and 0.3 ppm, respectively, in the Kalahari Goldridge banded-iron-formation-hosted gold deposit, and Au in pyrrhotite may sometimes exist as NPs, whereas As concentrations in pyrrhotite and pyrite are both low and lie in a narrow range from 6 to 22 ppm. Whether Au is present as NPs is important in ore dressing. The Au and As concentrations in pyrite from the Witwatersrand gold field range from 0.02 to 1.1 ppm and from 8 to 4000 ppm, respectively. The shape of the pyrite grains might prove to be an indicator of the hydrothermal influence on deposits of sedimentary origin, which implies the genesis of the deposits.

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“…Figure shows that four of the five TSFs studied in South Africa (hereafter referred to as TSFs 1–4) are located in Witwatersrand, Johannesburg, Gauteng, while the fifth TSF (hereafter referred to as TSF 5) is located in Klerksdorp, North‐West. These five TSFs are located within the major goldfields of the Witwatersrand basin, which is known as the world's greatest gold deposit . The Witwatersrand basin extends from the east of Johannesburg (East Rand goldfield) throughout the central (Central Rand goldfield) and western parts of Johannesburg (West Rand and West Wits goldfields) before finally reaching the Klerksdorp goldfield 40 km south‐west of the West Wits goldfield and lastly the Welkom goldfield further down south of the Klerksdorp goldfield .…”

Section: Methodsmentioning

confidence: 99%

“…These five TSFs are located within the major goldfields of the Witwatersrand basin, which is known as the world's greatest gold deposit . The Witwatersrand basin extends from the east of Johannesburg (East Rand goldfield) throughout the central (Central Rand goldfield) and western parts of Johannesburg (West Rand and West Wits goldfields) before finally reaching the Klerksdorp goldfield 40 km south‐west of the West Wits goldfield and lastly the Welkom goldfield further down south of the Klerksdorp goldfield . The Witwatersrand basin is located on a granite‐greenstone basement known as the Kaapvaal Craton and consists of a white quartzite ridge, which forms the lowermost stratigraphic layer of the basin …”

Section: Methodsmentioning

confidence: 99%

Ambient PM₁₀ and Respirable Dust Levels Near Gold Mine Tailings Storage Facilities in South Africa

Dekker¹,

Gulumian

2019

CLEAN Soil Air Water

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Gold mine tailings storage facilities (TSFs) contribute largely to high dust levels in the Gauteng and North‐West provinces, South Africa, and are seen as a public health concern. Currently, the South African National Ambient Air Quality Standard for PM10 is 75 μg m−3 (24 h) and no limits have yet been set for respirable PM4 levels. This study investigates the ambient PM10 levels close to three TSFs as well as respirable PM4 levels of school learners at various distances from five TSFs during the dry and wet season. The results show that the ambient PM10 levels exceeded the current limit to a large degree between three and five times during the sampling period at the three TSFs studied. Analysis of wind speed, direction, and frequency show that emissions from two of the three TSFs could have been a possible dust source contributing to some of these exceedances. The respirable PM4 levels ranged from 10–130 μg m−3 (wet season) to 3–173 μg m−3 (dry season). For two TSFs studied, sampling sites close to the TSFs showed significantly higher PM4 levels compared to those further away, which was, however, likely not the result of TSF emissions but rather from other dust‐generating sources. Overall, these results reveal high PM10 levels in surrounding communities, which should be monitored and investigated further.

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A Review of the Witwatersrand Basin - The World’s Greatest Goldfield

Cited by 60 publications

References 0 publications

Geophysical characterization of the Daskop granophyre dyke and surrounding host rocks, Vredefort impact structure, South Africa

Geophysical characterization of the Daskop granophyre dyke and surrounding host rocks, Vredefort impact structure, South Africa

Invisible Gold in Pyrite from Epithermal, Banded-Iron-Formation-Hosted, and Sedimentary Gold Deposits: Evidence of Hydrothermal Influence

Ambient PM₁₀ and Respirable Dust Levels Near Gold Mine Tailings Storage Facilities in South Africa

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A Review of the Witwatersrand Basin - The World’s Greatest Goldfield

Cited by 60 publications

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Geophysical characterization of the Daskop granophyre dyke and surrounding host rocks, Vredefort impact structure, South Africa

Geophysical characterization of the Daskop granophyre dyke and surrounding host rocks, Vredefort impact structure, South Africa

Invisible Gold in Pyrite from Epithermal, Banded-Iron-Formation-Hosted, and Sedimentary Gold Deposits: Evidence of Hydrothermal Influence

Ambient PM10 and Respirable Dust Levels Near Gold Mine Tailings Storage Facilities in South Africa

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Product

Resources

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Ambient PM₁₀ and Respirable Dust Levels Near Gold Mine Tailings Storage Facilities in South Africa