eW/FS/WE/001
The water environment
Physiography: Geology
South Africa has a long and complex geological history which goes
back some 3.7 billion years, and the country is blessed with an
amazing array of mineral resources of various ages. South Africa
ranks second only to the United States in production of the greatest
variety of mineral commodities in the world. Only two strategic
minerals are not available in adequate amounts in the country: crude
oil and commercially viable bauxite, the principal ore of aluminium.
The more than 65 mineral commodities known to occur within South
Africa continue to be vital for the growth of the country’s economy.
http://www.geotimes/org
South Africa not only hosts some of the oldest rocks in the world,
(source of South Africa’s great mineral wealth) but also some of the
oldest known fossils. The famous Bushveld Complex, the earth’s
largest ore deposit, hosts the largest platinum, chromium and
vanadium deposits in the world. http://www.gssa.org.za/
Large sedimentary basins of the Kaapvaal Craton hold some of
South Africa’s richest mineral resources. It is also the keystone on
and around which the rest of the geological formations of South Africa
have developed. It underlies the north eastern part of the country. It
is made up largely of Archean gneisses and granitoids, along with
lesser volumes of metamorphosed volcanic and sedimentary rocks
known as greenstone belts — the best known of which is the
Barberton greenstone belt, from which more than 10.93 million
ounces of gold have been produced.
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AA3
The Premier diamond pipe near Pretoria is the oldest productive
diamond-bearing kimberlite in South Africa; it was intruded into the
Kaapvaal Craton 1.3 billion years ago. The Venetia kimberlites, from
which the largest quantities of diamonds in South Africa are currently
produced, are significantly younger at 560 million years old, while the
bulk of the productive kimberlites were emplaced less than 200 million
years ago, during the breakup of Gondwanaland. It is widely believed
that for kimberlites to host diamonds, and bring them to the surface,
they must be intruded at great depths into thick, stable crustal zones,
such as the Kaapvaal Craton.
The auriferous (gold-containing) sedimentary strata of the
Witwatersrand Supergroup are confined to a basin south of
Johannesburg, measuring some 320 kilometers by 160 kilometers,
and were deposited between about 3.1 and 2.7 billion years ago. The
reefs vary widely, but the majority are conglomerate, with pebbles of
quartz and chert in a matrix of quartz grains, silicate and various
sulphides, mainly pyrite. They range from thin, small-pebble reefs,
often with great lateral extent, to thick conglomerate.
Between 2.6 and 2.1 billion years ago, infilling of the Transvaal and
Griqualand West basins occurred. The rocks contained in these
basins include enormous resources of dolomite and limestone, along
with more than three-quarters of the world’s exploitable manganese,
substantial deposits of banded iron formation and some lead/zinc
deposits.
Andalusite (containing aluminium and silicate) mineralization occurs in
the pelitic strata of the Transvaal basin, where they fall within the
metamorphic aureole of the Bushveld Complex that intruded the
Transvaal Supergroup sediments about 2,050 million years ago. This
complex is the world’s largest known layered intrusion, with an
estimated aerial extent of 66,000 square kilometers. At its base is a
suite of mafic (blend of magnesium and iron) and ultramafic rocks that
hosts more than half of Earth’s chrome ore and platinum-group metals
(PGM), as well as significant deposits of vanadium, iron, titanium,
copper and nickel. Its overlying acidic rocks contain fluorspar, tin and
copper mineralization. A substantial amount of black norite and red
syenite of the Bushveld Complex is quarried as building and
monumental stone.
Copper refinery
The vast Karoo basin, which covers about two-thirds of South Africa,
hosts the fluviodeltaic sediments and coals of the extensive
Carboniferous-age Ecca Group. These coal horizons are actively
exploited mainly in the northern and eastern parts of the basin and
provide the main source of energy for South Africa.
Contact: ewisa@wamsys.co.za URL: www.waterinfo.co.za
Prepared by: eWISA
Copyright: All right reserved
Sponsored by: