- Title
- The sedimentology and depositional model of VS5 reef at Beatrix mine and surrounding areas of the Freestate Goldfield, South Africa
- Creator
- Shivambu, Steven
- Date Issued
- 2017
- Date
- 2017
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10962/4942
- Identifier
- vital:20745
- Description
- Historically, placers of economic importance at Sibanye Gold's Beatrix No. 3 Shaft were Beatrix Reef, Aandenk Reef and Composite of the two reefs. Recently, the VS5 placer has emerged to be a significant contributor of ore tonnages mined on the Shaft as mining advances into deeper levels towards the northern portion of the mine lease area. Gold concentration in the VS5 Reef is highly variable from uneconomic, through marginal to economic gold values. A good knowledge of the sedimentological framework of the VS5 Reef was considered necessary in order to interpret the variable distribution of the gold within the VS5 placer. The aim of this study was to determine the depositional environments that played a major role during the formation of the VS5 placer by means of investigating the macroscopic sedimentological parameters of this particular reef. These sedimentological parameters were used as the basis for the subdivision of VS5 Reef into different facies recognized in the mine and surrounding areas. It was recognized that the VS5 placer was formed in a distal, braided fluvial environment by the reworking of the pre-existing Aandenk Reef by new materials containing significant amount of nondurable materials (see definition on page xii) such as shale detritus. Where there is no evidence of reworking of the older Aandenk Reef, the VS5 Reef occurs as poorly sorted, polymictic conglomerate with abundance of non-durable detritus. This is referred to as the Immature (IV) VS5 facies and occurs in the northern portion of the study area. The degree of reworking of the gravel bars by waves and current action resulted in the formation of well sorted, oligomictic conglomerates of the Beatrix facies in the southern portion of the mine. At the boundaries between the Immature VS5 and Beatrix facies occurs the Transitional (Sub-mature) VS5 facies, characterized by reef comprising a polymictic upper portion and a basal more mature oligomictic unit. The Transitional VS5 facies extends across the current central northern mining faces of Beatrix No. 3 Shaft with a northwest-southeast trend. There is a strong correlation between the VS5 lithofacies and distribution of gold mineralization. The Immature VS5 facies is poorly mineralized, with gold values averaging 200 c.m.g/t and lower. The Transitional (Sub-mature) VS5 facies has elevated gold values, ranging from 300 c.m.g/t to 1500 cm.g/t. Mineralization in this unit tend to be bottom loaded as well as at the base of each cyclic unit. The Beatrix facies records the highest grades averaging >1500 cmg/t. The improved understanding of the VS5 lithofacies made it possible to predict gold mineralization and aid planning to mine into viable VS5 areas.
- Format
- 78 leaves
- Format
- Publisher
- Rhodes University
- Publisher
- Faculty of Science, Geology
- Language
- English
- Rights
- Shivambu, Steven
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RU Department of Geology
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | Microsoft Word - S.Shivambu - Final Library Copy (17Aug2016).docx | 8 MB | Adobe Acrobat PDF | View Details Download |