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probably gold and other minerals that washed into the basin, forming a layer of conglomerate
from which the rich gold mines of South Africa extract the ore. Indeed, half of the world's gold
has come from this area, some 50,000 tons. And just like the Southern African inland sea, the
world oceans contain huge deposits of gold but mining them is nearly impossible. On the
eastern rim of the basin are the Barberton Mountains, the only remaining mountains along the
eastern edge and the world's oldest mountains, which make up the Barberton Greenstone
Complex. Within these old mountains are supposedly the signs of the first ancient life found in
old rocks called stromatolites formed from cyanobacteria; although this is sometimes disputed.
Parts of Australia share these types of rocks with the Barberton Mountains, which makes sense
given the history of the craton movement. These ancient cyanobacteria that could convert
carbon dioxide to oxygen are believed to be source of oxygen. These mountains, where the
Komati River has cut through the ridges, also supposedly show evidence that a month was
shorter at that time based on the tidal marks found and maybe a month was 18 days long. At
one time the area was supposedly 5 km lower, beneath 3km of seawater. Some of the rocks
discovered here in 1969 by twin brothers Richard and Morris Viljoen date back to Archaean
lava flows that are the oldest known rocks and are called komatiites from the lava flows and
that are believed to be the hottest lava flows ever at some 1650 degrees Celsius. These
komatiites flows may have even been global at a time when the mantle of the earth was 500
degrees Celsius higher and typically were more liquid than basalt flows (basalt is like treacle
flows, like in the Hawaiian Islands, and is about 1200 degrees Celsius) and were thinner at
about 1cm in thickness. Komatiite rocks are rich in particularly magnesium and are associated
with Archaean era deposits of gold and nickel mines.
Extending deep into the mantle the craton's volcanoes would bring molten rock magna to the
surface forming granite pipes and craters or spreading horizontal flows of basalt. Some of
these pipes, called kimberlite, formed places like Kimberly and Cullinan, the latter the site of
the world's largest gem quality diamond—3,107 carats. Kimberlite pipes, shaped like giant
carrots, are among the deepest volcanic magma plumes extending down to 450 km under
typically Archaean cratons and carry diamonds up like a elevator from the depths where
diamonds form at about 150 km depth, either in contact with inorganic or organic carbon, at
extreme pressures and about 900 to 1300 degrees Celsius.
[Research by Trond Torsvik published in Nature has shown that the kimberlite diamond
generations occur in mantle plumes at depths of at least 150km, but may be even as deep as
1,700 km into the earth's mantle. They are related to the most ancient cratons that occur in
Southern Africa and the mid-Atlantic mantle fracture of at least 2.5 billion years and 300 km
thickness. The kimberlite eruptions also appear to have been related to slow continental
movements of Southern African cratons at a speed of 1 to 3.5cm per year. Indeed, Cande and
Stegman reported that the hot magma plume near Reunion some 63 million years ago rapidly
pushed the Indian subcontinent into the Eurasian continent. Botswana (32 million carats),
Namibia (2 million), Angola (8 million), South Africa (5 million) and Zimbabwe produce
some 50 million carats of diamonds per year and 60% of the world trade in diamonds is
controlled by De Beers, founded partly by Cecil Rhodes but also the Oppenheimer family. The
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