Traces of the world's oldest glaciers found under a large gold deposit

A team of scientists led by Johannesburg University geologist Axel Hofmann analyzed rock formations near Durban on the east coast of South Africa. It turned out that they contain glacial deposits, whose age is estimated at 2.9 billion years. This makes them the oldest known on Earth.

Glacier tracks found in rocks speckled with oxygen isotopes and lying under the world's largest gold deposits.

Bindeman and colleagues measured oxygen isotope levels in sandstone and shale samples and found that that they have the lowest levels of oxygen-18 of all such deposits analyzed so far since. They also had very high amounts of oxygen-17, indicating that the rocks were formed at low temperatures.

“Combine these geochemical data with moraines data and you have glaciers – the oldest glaciers found on Earth,” Bindeman added.

This discovery could add new lines to a chapter in the history of the early Earth and explain how these gold mines formed. In addition, the location of the glacier raises interesting questions about periods of cooling in the ancient past.

The scientists' data points to a gradual climatic cooling of surface media, culminating in glacial conditions 2.9 billion years ago.

It is believed that during its history the Earth froze twice: 700 and 650 million years ago. But researchers are wondering if the planet was a completely frozen wasteland, or if it looks more like a ball of slush. The deposits found in South Africa may point to the earliest known period of global cooling.

The study of the samples was published in Geochemical Perspectives Letters. In the near future, scientists will be engaged in a deeper study of the data obtained.