The largest Deposit of gold on the Earth made by bacteria
In the formation of huge deposits of gold on Earth, the key role played by bacteria. Deposits securities alloy on the planet could occur only in a small gleam of time between the creation of life and the saturation of the atmosphere with oxygen.
Therefore, today, new deposits of gold does not occur, say the authors of a paper in the journal Nature Geoscience. Briefly about the study informs New Scientist.
After the discovery of the field Witwatersrand (South Africa) in 1886 there has mined approximately 40 thousand metric tons of gold is almost half of all gold ever acquired. The field itself appeared 3 billion years ago - and about the mechanisms of its appearance long geologists argue.
There is no doubt that on the surface of the Earth alloy fell in consequence of the erosion of gold-bearing veins in granitic rocks Chapmansboro craton. It is unclear just how tons of gold were found at several hundred km to the South.
Considering the opinion of Christoph Heinrich (Christoph Heinrich) from the Swiss Federal scientific and technical Institute, then played the role of not just the mechanical processes of leaching of the metal pieces rivers of rocks. Gold chose from river water microbial mats from the shallow waters of the Witwatersrand, the scientist believes.
3 billion years ago in the atmosphere of the planet was almost no oxygen (the gas after 500 million years started to produce algae and cyanobacteria). The air was saturated with sulfur gases (like hydrogen sulfide) that are emitted into the atmosphere volcanoes. These gases returned to the earth's surface as acid rain. Gold was formed with grey soluble compounds, which were dissolved in water: from the same metal selected bacteria.
If the atmosphere was more air, he would've reacts with sulfur and gold and would kill them long before they reached the shallow reservoirs with microbial mats.
"And now - the question billion bucks: there are other deposits in the same process?", "says Heinrich. If the answer is positive (i.e., gold moves in the gold placers of sand), the explorers will be advised to seek not rich alloy sand and traces of pre-Cambrian life, to start a saturated carbon shales.
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