Nav: Home

The formation of gold deposits in South Africa

April 20, 2017

At a first glance, the Witwatersrand basin, the largest known gold resource on our planet, is not automatically related to ocean research. However, in its 3 billion years old geological history, the Witwatersrand basin in South Africa has been covered by seawater, but experienced also episodes of drying out, flooding and erosion by rivers and the repeated coverage by seawater. In 1852, the English prospector J.H. Davis discovered the first gold in the Witwatersrand, leading to the South African gold rush and the discovery of much more gold deposits within the basin. Although the Witwatersrand has been subject for decades of research, the genesis of gold and uranium ore is still unclear.

A group of scientists from Canada and the GEOMAR Helmholtz Centre of Ocean Research Kiel, successfully unravelled some mechanisms of the ore-forming process using complex analytical techniques. The results were recently published in the scientific journal Precambrian Research.

In this study, the scientists analysed samples from the Witwatersrand ore deposits with high-resolution scanning- and transmission-electron microscopes, and the processed their data using novel 2D and 3D software. "We were able to find out that fossil oil, that has been formed by organic matter derived from the first living organisms on Earth, mobilized uranium in the basin. Uraninite nanoparticles flocculated in the oil and formed uranium ore", explains Dr. Sebastian Fuchs from the GEOMAR, the first author of the study. "Hot hydrothermal fluids, similar to those fluids that we find today in modern seafloor Black Smoker systems, transported dissolved gold and formed oil-in-water emulsions at the site of the deposits. The oil droplets in the hydrothermal fluids initiated the efficient chemical precipitation of native gold and the formation of very complex-structured gold and uranium ore."

Using high-resolution imaging techniques, the researchers were able to visualize a to date unknown ore-forming process, in which migrating oil plays the dominant role in the distribution and concentration of metals. "With our method we have been able to show remnants of fossil oil entrapped in gold for the very first time" says Dr. Sebastian Fuchs.

"We are surprised to see such an intimate spatial relationship between the oil products and the metals", reports Dr. Fuchs. "We hope that our study gives new impulses to industry and science to explore new mineral deposits. Perhaps it is possible at some day to extract gold and other metals from mined crude oil".

With the methods used, it is now possible to study not only ore particles on the ocean floor in the range of millimetre to nanometre, but also the smallest fossils and living organisms, such as micro-organisms. "We are curious about what else we might discover on the ocean floor in the future", Fuchs concludes.
Note: This study was supported by a Canadian NSERC Discovery Grant.

Original work:

Fuchs, S.H.J., D. Schumann, A.E. Williams-Jones, A.J. Murray, M. Couillard, K. Lagarec, M.W. Phaneuf, H. Vali, 2017: Gold and uranium concentration by interaction of immiscible fluids (hydrothermal and hydrocarbon) in the Carbon Leader Reef, Witwatersrand Supergroup, South Africa. Precambrian Research, 293, 39-55,

Helmholtz Centre for Ocean Research Kiel (GEOMAR)

Related Gold Articles:

Mathematicians find gold in data
Russian mathematicians and geophysicists have made a standard technique for ore prospecting several times more effective.
Actively swimming gold nanoparticles
Bacteria can actively move towards a nutrient source -- a phenomenon known as chemotaxis -- and they can move collectively in a process known as swarming.
Gold for silver: A chemical barter
From effective medicines to molecular sensors to fuel cells, metal clusters are becoming fundamentally useful in the health, environment, and energy sectors.
Gold for iron nanocubes
Hybrid Au/Fe nanoparticles can grow in an unprecedentedly complex structure with a single-step fabrication method.
Resolving the 'invisible' gold puzzle
In Carlin-type gold deposits, which make up 75% of the US production, gold does not occur in the form of nuggets or veins, but is hidden -- together with arsenic -- in pyrite, also known as 'fool's gold.' A team of scientists has now shown for the first time that the concentration of gold directly depends on the content of arsenic in the pyrite.
The first nucleophilic gold complex
A collaborative research effort between the departments of chemistry at the University of Oxford and University of Jyväskylä has resulted in the discovery of a gold compound exhibiting nucleophilic behavior hitherto unknown for molecular gold.
Gold recycling
'Urban mining', the recycling of precious metals from electronic gadgets, becomes ever more important, although processes that are both efficient and environmentally benign are still scarce.
Light triggers gold in unexpected way
Rice University researchers have discovered a fundamentally different form of light-matter interaction in their experiments with gold nanoparticles.
How to melt gold at room temperature
When the tension rises, unexpected things can happen -- not least when it comes to gold atoms.
'Himalayan gold' on the brink
Stanford researchers show how warmer winters and booming demand for one of the world's most expensive medicinal species may hurt ecosystems and communities in the Himalayas.
More Gold News and Gold Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.