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Not Only Metals: Scientists Find Traces of Ancient Glaciers Under South Africa's Gold Fields

08:44, 14 July 2023

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Rasina Musallimova

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Glaciers are traditionally associated with the North and South Poles. It sounds impossible that they could be found in South Africa. However, scientists from South Africa and the US has recently refuted this misconception.

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Traces of a glacier have been discovered beneath the world's largest gold deposits in South Africa. The finding dates from 2.9 billion years ago, making it the oldest glacier on Earth, as stated in the study conducted by Axel Hofmann (University of Johannesburg, South Africa) and Ilya Bindeman (University of Oregon, US).

According to the research paper published in the journal Geochemical Perspectives Letters, the mentioned glacier provides yet further evidence of major climate shifts on Earth in the past, according to the scientists.

In addition to glacial moraines (glacial deposits created by the glacier), the reliability of the discovery is confirmed by geochemical studies, as Ilya Bindeman said.

"We looked at relative amounts of three oxygen isotopes, ¹⁶O, ¹⁷O, and ¹⁸O. These are all types of oxygen, but have very slightly different weights. We found that these rocks had very low amounts of ¹⁸O, and very high amounts of ¹⁷O, indicating that they were formed at icy temperatures. This means ice. Couple that geochemical evidence with the moraine evidence, and it means glaciers, the oldest glaciers yet found on Earth,” the researcher revealed.

Professor Hofmann also explained possible circumstances that facilitated the formation of the glacier.

“It may be that this area was close to the poles. Another possibility is that the whole Earth was in a ‘snowball Earth’ period, when low atmospheric concentrations of CO2 and CH4 led to a ‘reverse greenhouse effect’, causing much of the planet to freeze,” the co-author said.

An assumption has also been made about the impact of the glacier on the influence of the glacier on the formation of the precious metal.

“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,” the scientists noted.

The method of triple isotope analysis could contribute to the discovery of traces of ancient glaciers, which consequently would stimulate the study of the Earth's historical climate, the scientists believe.