The Saaiplaas Quartzite Member: A Braided System of Gold‐ and Uranium‐Bearing Channel Placers within the Proterozoic Witwatersrand Supergroup of South Africa

Buck, S. G.

doi:10.1002/9781444303773.ch43

Cited by 10 publications

(8 citation statements)

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“…These areas include the relatively coarsegrained troughs of the bedload sheets (Table 3), small-scale scours associated with pebble clusters (see Bennett, 1992;Bennett & Bridge, 1995), and on the erosional bed surfaces following degradation (Table 3). The concentration of heavy minerals in bedform troughs has been noted in other studies (Minter, 1978;Buck, 1983;Kuhnle, 1986;Kuhnle & Southard, 1990). In addition, heavy minerals were observed in large concentrations on the bottom of the flume channel when re-homogenizing the sediment between runs.…”

Section: Heavy Mineral Entrainment and Sortingsupporting

confidence: 78%

“…All notation used herein is consistent with Bennett (1992). see Minter, 1978;Buck, 1983) but was selected to facilitate heavy mineral identification and recovery (see also Kuhnle, 1986). Bedload transport rate was determined by collecting the sediment discharge (which was all bedload) at the downstream end of the flume in a 0.045-m" nylon sample bag secured to the inside of a 0.18-m3, nylon-lined steel basket.…”

Section: Experimental Equipment and Proceduresmentioning

confidence: 99%

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An experimental study of flow, bedload transport and bed topography under conditions of erosion and deposition and comparison with theoretical models

Bennett

Bridge

1995

Sedimentology

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The nature of flow, sediment transport and bed texture and topography was studied in a laboratory flume using a mixed size-density sediment under equilibrium and non-equilibrium (aggradational, degradational) conditions and compared with theoretical models. During each experiment, water depth, bed and water surface elevation, flow velocity, bed shear stress, bedload transport and bed state were continuously monitored. Equilibrium, uniform flow was established with a discharge of about 0.05 m3 s ~ ', a flow depth of about 0-01 m, a flow velocity of about 0-81-0.88 m s *Present address: Department of Earth Sciences, University of Leeds, Leeds LS2 9JT, UK. 1 1 7 118 S. J. Bennett and J. S. Bridgeand non-equilibrium flow conditions, total and fractional bedload transport rates and changes in bed topography and texture very well.

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Section: Heavy Mineral Entrainment and Sortingsupporting

confidence: 78%

Section: Experimental Equipment and Proceduresmentioning

confidence: 99%

An experimental study of flow, bedload transport and bed topography under conditions of erosion and deposition and comparison with theoretical models

Bennett

Bridge

1995

Sedimentology

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“…The reworking of such fan deposits is a well-documented mechanism for the concentration of heavy minerals (e.g. Buck 1983;Buck & Minter 1985).…”

Section: Goldmentioning

confidence: 99%

Geomorphological controls on the distribution of placer deposits

Sutherland¹

1985

JGS

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The objective of this paper is to show that the global distribution of placer deposits is largely a product of variation (both at present and in the recent geological past) in geomorphological processes acting at the earth's surface, given suitable primary mineral sources. The distribution of known placers of diamonds and gold as well as certain littoral placers is considered in relation to the occurrence and tectonic setting of the primary sources of the various minerals. Climatic controls of the many variables that are relevant to placer formation (e.g. weathering, rate of erosion, nature of sediment supply, opportunities for sediment reworking) are discussed in terms of broad morphogenetic regions. Five such regions are identified on the basis of distinctive combinations of the geomorphological processes responsible for placer formation. Global changes in climate and accompanying changes in the surface processes responsible for placer formation during both the Tertiary and, more particularly, the Quaternary have been important in producing the alternation between erosional and depositional conditions that is especially suitable to placer formation. Primary source tectonic setting and morphogenetic processes all interact to allow the identification of regions in which placer formation is favoured.

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“…Sedimentological studies have also concentrated more on placers in the Witwatersrand Supergroup (e.g. Minter, 1978;Smith & Minter, 1980;Tankard et al, 1982;Buck, 1983), and less is known in detail about the Ventersdorp placers.…”

Section: Introductionmentioning

confidence: 99%

The Ventersdorp Contact placer: a gold‐pyrite placer of stream and debris‐flow origins from the Archaean Witwatersrand Basin of South Africa

Krapež

1985

Sedimentology

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Five local varieties of the Ventersdorp Contact placer at the East Driefontein Gold Mine, Carletonville, are distinguished by clast‐type assemblage, reflecting discrete provenances. The placer further comprises six lithofacies which are not restricted to specific provenance‐varieties. The six lithofacies are: massive, matrix‐supported conglomerate (facies Gms): massive, or crudely bedded, clast‐supported conglomerate (facies Gm); channel‐based conglomerate (facies Gt); single clast layers (facies Glag); horizontally stratified sandstone (facies Sh); and trough cross‐stratified sandstone (facies St). Facies Gms represents debris‐flow deposits, whereas the other facies are stream deposits. Lithofacies and provenance‐varieties are complexly interrelated in local environments, which are themselves complexly related to geomorphic elements of a degradation surface. The maximum thickness of the placer is 7 m. The placer was deposited on a hard, i.e. non‐alluvial, bedrock surface, suggesting that it is a pediment mantle. It owes its preservation to a capping of conformably overlying basalts. Economic gold mineralization is present in all the conglomerate facies and all the provenance‐varieties. Gold concentrations are high in gravel‐bar deposits and channel fills but are not restricted to these environments. A major feature of gold concentration is its variability between provenance‐controlled varieties. The gold concentration of a specific primary source is interpreted to be a major control on gold concentration in the final deposit. The origin of the placer as a pediment mantle, and its subsequent preservation by lava‐flows, suggests that there was little potential for selective reworking of heavy minerals. Nevertheless, the Ventersdorp Contact placer on the Carletonville Goldfield is one of the richest gold placers in the Witwatersrand Basin.

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The Saaiplaas Quartzite Member: A Braided System of Gold‐ and Uranium‐Bearing Channel Placers within the Proterozoic Witwatersrand Supergroup of South Africa

Cited by 10 publications

References 0 publications

An experimental study of flow, bedload transport and bed topography under conditions of erosion and deposition and comparison with theoretical models

An experimental study of flow, bedload transport and bed topography under conditions of erosion and deposition and comparison with theoretical models

Geomorphological controls on the distribution of placer deposits

The Ventersdorp Contact placer: a gold‐pyrite placer of stream and debris‐flow origins from the Archaean Witwatersrand Basin of South Africa

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