Witwatersrand basin
Encyclopedia
| Gold Production on the Witwatersrand 1898 to 1910 | ||||
|---|---|---|---|---|
| Year | No. of Mines |
Gold output (fine ounces) |
Value (GB£ Pound sterling The pound sterling , commonly called the pound, is the official currency of the United Kingdom, its Crown Dependencies and the British Overseas Territories of South Georgia and the South Sandwich Islands, British Antarctic Territory and Tristan da Cunha. It is subdivided into 100 pence... ) |
Relative 2010 value (GB£ Pound sterling The pound sterling , commonly called the pound, is the official currency of the United Kingdom, its Crown Dependencies and the British Overseas Territories of South Georgia and the South Sandwich Islands, British Antarctic Territory and Tristan da Cunha. It is subdivided into 100 pence... ) |
| 1898 | 77 | 4,295,608 | £15,141,376 | £6,910,000,000 |
| 1899 (Jan-Oct) | 85 | 3,946,545 | £14,046,686 | £6,300,000,000 |
| 1899 (Nov- 1901 Apr) | 12 | 574,043 | £2,024,278 | £908,000,000 |
| 1901 (May-Dec) | 12 | 238,994 | £1,014,687 | £441,000,000 |
| 1902 | 45 | 1,690,100 | £7,179,074 | £3,090,000,000 |
| 1903 | 56 | 2,859,482 | £12,146,307 | £5,220,000,000 |
| 1904 | 62 | 3,658,241 | £15,539,219 | £6,640,000,000 |
| 1905 | 68 | 4,706,433 | £19,991,658 | £8,490,000,000 |
| 1906 | 66 | 5,559,534 | £23,615,400 | £9,890,000,000 |
| 1907 | 68 | 6,220,227 | £26,421,837 | £10,800,000,000 |
| 1908 | 74 | 6,782,538 | £28,810,393 | £11,700,000,000 |
| 1909 | 72 | 7,039,136 | £29,900,359 | £12,200,000,000 |
| 1910 | 63 | 7,228,311 | £30,703,912 | £12,400,000,000 |
The Witwatersrand Basin is a geological formation in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
holding the world's largest known gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
reserves and having produced over 1.5 billion ounces. The basin straddles the old provinces of Transvaal
Transvaal Province
Transvaal Province was a province of the Union of South Africa from 1910 to 1961, and of its successor, the Republic of South Africa, from 1961 until the end of apartheid in 1994 when a new constitution subdivided it.-History:...
and the Orange Free State
Orange Free State
The Orange Free State was an independent Boer republic in southern Africa during the second half of the 19th century, and later a British colony and a province of the Union of South Africa. It is the historical precursor to the present-day Free State province...
and is of the same period as the Vredefort impact
Vredefort crater
Vredefort crater is the largest verified impact crater on Earth. It is located in the Free State Province of South Africa and named after the town of Vredefort, which is situated near its centre. The site is also known as the Vredefort dome or Vredefort impact structure...
of 2.023 Ga ago, and the Bushveld Igneous Complex
Bushveld igneous complex
The Bushveld Igneous Complex is a large layered igneous intrusion within the Earth's crust which has been tilted and eroded and now outcrops around what appears to be the edge of a great geological basin, the Transvaal Basin. Located in South Africa, the BIC contains some of the richest ore...
.
Nearly half of all the gold ever mined has come from the extensive Witwatersrand Basin that was first found near Johannesburg
Johannesburg
Johannesburg also known as Jozi, Jo'burg or Egoli, is the largest city in South Africa, by population. Johannesburg is the provincial capital of Gauteng, the wealthiest province in South Africa, having the largest economy of any metropolitan region in Sub-Saharan Africa...
in 1886. The gold occurs in reefs, or thin bands, that are mined at depths of down to 4,000 m - Mponeng gold mine currently being the world's deepest. Although many of the older mines are now nearly exhausted, the Witwatersrand Basin still produces most of South Africa's gold and much of the total world output. Silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
and iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
are recovered as gold-refining byproducts, and the basin also has coal mines, although they are bit players in the overall mining of the Basin.
Witwatersrand (meaning 'white water ridge' in Afrikaans
Afrikaans
Afrikaans is a West Germanic language, spoken natively in South Africa and Namibia. It is a daughter language of Dutch, originating in its 17th century dialects, collectively referred to as Cape Dutch .Afrikaans is a daughter language of Dutch; see , , , , , .Afrikaans was historically called Cape...
) is often called simply "the Rand," and is located in the Gauteng province (formerly a part of Transvaal
Transvaal Province
Transvaal Province was a province of the Union of South Africa from 1910 to 1961, and of its successor, the Republic of South Africa, from 1961 until the end of apartheid in 1994 when a new constitution subdivided it.-History:...
) of South Africa.
This sedimented craton
Craton
A craton is an old and stable part of the continental lithosphere. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates. They are characteristically composed of ancient crystalline basement rock, which may be covered by...
ic basin covers an elliptical area with a 300 km long major axis from Delmas
Delmas, Mpumalanga
Delmas is a small farming town situated east of Johannesburg in Mpumalanga, South Africa. The farms in the region produce maize, wheat, potatoes and chickens. The town was laid out in 1907 on the farm Witklip . The farm was owned by a Frenchman Frank Dumat, who decided to call the town "de le mas" ....
in the north-east to Theunissen
Theunissen
Theunissen is a small town that has the only wine estate, the Theunissen Wine Farm, in the Free State province of South Africa. It was founded by Boer War Commandant Helgaardt Theunissen...
in the south-west, with a small subsidiary basin at Kinross
Kinross, Mpumalanga
Kinross is a small gold mining town in Mpumalanga, South Africa with four gold mines in the region. The town, named after Kinross in Scotland, was established in 1915....
. Dotted outside the basin are older Archaean granites of between 3 and 3.2 Ga, some of which are exposed while others are covered by the much younger Karroo System. The Witwatersrand System is a sequence of shales, quartzites and conglomerates ranging in age from 2.7 Ga for the Hospital Hill subgroup to 2.4 Ga for the Turffontein subgroup. The Lower Witwatersrand is composed mainly of argillaceous clays and shales with occasional banded ironstone
Banded iron formation
Banded iron formations are distinctive units of sedimentary rock that are almost always of Precambrian age. A typical BIF consists of repeated, thin layers of iron oxides, either magnetite or hematite , alternating with bands of iron-poor shale and chert...
, a tillite and an intercalated lava flow, while the Upper Witwatersrand consists almost entirely of quartzites and conglomerates, with its own volcanic horizon.
Gold mines operating in the Witwatersrand Basin
On the East Rand, Ergo is run by East Rand Gold and Uranium Company South Africa Ltd., a company involved in the extraction of gold and uranium residue from slimes dams and sand dumps on the Central, East and Far East Rand, and to produce sulphuric acid.On the West Rand, Mponeng, Savuka and TauTona
TauTona
The TauTona Mine or Western Deep No.3 Shaft, is a gold mine in South Africa. At some deep it is currently home to the world's deepest mining operations.-Overview:...
, formerly known as Western Deep Levels, are managed by AngloGold Ashanti
AngloGold Ashanti
AngloGold Ashanti Limited is a global gold mining company. It was formed in 2004 by the merger of AngloGold and the Ashanti Goldfields Corporation.AngloGold Ashanti Limited is now a global gold producer with 21 operations on four continents...
, and Kusasalethu (previously Elandsrand) and Doornkop Mines are managed by Harmony Gold. South Deep, Kloof and Driefontein mines are operated by Goldfields
In the Vaal River
Vaal River
The Vaal River is the largest tributary of the Orange River in South Africa. The river has its source in the Drakensberg mountains in Mpumalanga, east of Johannesburg and about 30 km north of Ermelo and only about 240 km from the Indian Ocean. It then flows westwards to its conjunction...
area, AngloGold Ashanti operate Great Noligwa, Kopanang, Tau Lekoa and Moab Khotsong.
In the Free State Province, Harmony Gold runs Bambanani, Tshepong, Phakisa, Target, Masimong and Joel mines.
External links
- http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V72-48CGKPP-7&_user=10&_coverDate=01%2F01%2F1990&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1467112250&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b46f960443a1bee1344abf3a416a8bcf&searchtype=aRelationships between the Vredefort structure and the Witwatersrand basin within the tectonic framework of the Kaapvaal craton as interpreted from regional gravity and aeromagnetic data]
- River of the Crater