Uncover the secrets of an ancient deep freeze as experts present their remarkable findings: a treasure trove of 2.9 billion-year-old glacial deposits hidden beneath South Africa’s world-renowned gold fields.
Traces of the Oldest Glaciers Ever Found: World’s Largest Gold Deposits in South Africa Hide World’s Oldest Glaciers as Revealed By New Study
New findings presented at the Goldschmidt geochemistry conference in Lyon reveal that scientists have made a significant discovery: the remnants of the world’s oldest known glaciers, dating back 2.9 billion years, have been unearthed in rocks beneath South Africa’s vast gold deposits.
This astonishing revelation suggests the presence of continental ice caps during that period. It also proposes the intriguing possibility that the region was either located closer to the poles or that the Earth experienced a hitherto unknown “snowball Earth” phase characterized by extremely cold weather.
The research, which has undergone recent peer-reviewed publication, provides the first-ever comprehensive account of these remarkable findings.
Despite widespread agreement among scientists that the early Earth witnessed substantial climate variations, concrete evidence elucidating the precise conditions during that era has been challenging to obtain.
Now, Professor Axel Hofmann from the University of Johannesburg, South Africa, and Professor Ilya Bindeman from the University of Oregon, USA, have made a breakthrough.
By analyzing relative oxygen isotope concentrations in ancient rocks and examining physical proof, they have uncovered compelling evidence of glaciers that existed 2.9 billion years ago.
Ilya Bindeman commented, “We found extremely well-preserved glacial deposits close to the gold fields of South Africa.”
The region under investigation stands out as a rare haven that has preserved its original state since the early Earth. The preserved remnants discovered in this area are fossilized glacial moraines, which represent the remnants left behind as a glacier slowly recedes and diminishes in size. These findings constitute the most ancient moraine deposits ever unearthed. Moreover, through an examination of oxygen isotopes in these rocks, they established a strong correlation that indicates the climate was frigid during the deposition of these rocks.
“We looked at relative amounts of 3 oxygen isotopes, 16O, 17O, and 18O. These are all types of oxygen but have very slightly different weights.”
The analysis revealed that these rocks exhibited remarkably low levels of 18O and notably high levels of 17O, suggesting that they originated under freezing temperatures.
“This means ice. Couple that geochemical evidence with the moraine evidence, and it means glaciers, the oldest glaciers yet found on Earth.”
The researchers propose two plausible explanations for these findings:
One potential explanation is that this particular area was situated near the poles during that time. Another possibility is that the entire Earth experienced a period known as “snowball Earth,” characterized by reduced atmospheric levels of CO2 and CH4, resulting in a ‘reverse greenhouse effect’ that led to widespread freezing across the planet.
Scientists speculate that such global cooling episodes may have occurred a few times in more recent history.
If confirmed, this would be the earliest documented occurrence of such a significant global cooling period. Both possibilities hold profound scientific significance and warrant further investigation.
Axel Hofmann added “The largest sedimentary gold deposits in the world are found in slightly younger rocks sitting above the rocks we studied. It’s possible that a change from icehouse to greenhouse conditions may have aided in the formation of those gold deposits, but this needs to be confirmed and requires further work”.
Dr. Andrey Bekker, Associate Professor at the Department of Earth & Planetary Sciences, University of California, Riverside, provided additional insight, stating, “Evidence for glaciation of this age has been hotly discussed and debated for decades based on sedimentological evidence with suggestions ranging from high altitude to high latitude glaciation.
“Triple oxygen isotope analysis add an entirely new line of evidence to this argument. The biogeochemical carbon cycle not only controls climate, but also atmospheric oxygen content and these data are likely to trigger follow-up studies on the transient oxygenation at that time.”
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