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South African Gold Deposits Conceal The World's Oldest Glaciers

South African gold deposits conceal world's oldest glaciers as researchers make a groundbreaking revelation by identifying remnants of the most ancient glaciers ever found, estimated to be approximately 2.9 billion years old.

Daisy-Mae Schmitt
Jul 13, 2023361 Shares30072 Views
South African gold deposits conceal the world's oldest glaciersas researchers make a groundbreaking revelation by identifying remnants of the most ancient glaciers ever found, estimated to be approximately 2.9 billion years old. The existence of these ancient glaciers provides compelling evidence of continental ice caps during that era.
This finding implies two possibilities: either the region where these rocks were found was positioned nearer to the Earth's poles than it is today, or it indicates the occurrence of an unprecedented period of severe cold weather known as a "snowball Earth," where substantial parts of the planet were covered in ice.
The northeastern region of South Africa showcases a diverse tapestry of landscapes, ranging from expansive plains adorned with unique rock formations to coastal wetlands and even unexpected dense coniferous forests. These forests, remnants of a bygone colonial era, were established by introducing non-native tree species from Europe, particularly massive pine plantations.
However, beneath this remarkable array of natural wonders, an extraordinary geological treasure awaits. More than three miles below the surface, lies evidence of Earth's ancient history in the form of rock layers that bear witness to the planet's earliest episodes of extreme cold, representing a profound deep freeze of immense significance.
The findings presented in this piece draw upon the research article titled "Earth's first glaciation at 2.9 Ga revealed by triple oxygen isotopes," authored by A. Hofmann and I.M. Bindeman, published in Geochemical Perspectives Letters. The study's outcomes will be showcased during the Goldschmidt geochemistry conference in Lyon, specifically in talk number 17171 titled "A model of unidirectional and accumulative fluxes from mantle to the lithosphere explaining crustal growth via triple oxygen isotope mass balance throughout Earth's history."
The term "Snowball Earth" has been used to describe various icy episodes in the early history of our planet, a catchy phrase that geologists appreciate. However, prior to the recent discovery in South Africa, the Huronian glaciation held the distinction of being Earth's oldest known ice age, and it was truly remarkable.
South Africa's complex landscape showing its mountains
South Africa's complex landscape showing its mountains
Spanning over 200 million years, this period commenced approximately 2.45 billion years ago. Although there were intermittent climate fluctuations during the Huronian, including relatively warmer and more humid periods, there were several prolonged global freezes lasting for at least 10 million years.
The recent findings in South Africa, at field sites near the border of Eswatini (formerly Swaziland), have unveiled the existence of Earth's earliest glaciers, which formed around half a billion years before the Huronian glaciation. Our understanding of this particular era in Earth's history remains limited.
When the South African glaciers emerged, the planet was approximately 1.6 billion years old and already harbored microbial life, including some of the earliest multicellular organisms. However, it would take over a billion years for more complex forms of life to evolve.
In their quest to uncover the oldest glaciers, the research team employed an analysis of oxygen isotopes present in the rock layers, successfully identifying the distinct geochemical signature indicative of a frozen climate. Within these layers, the scientists also documented the earliest known moraine-a distinct accumulation of debris left behind as a glacier melts and retreats.
The remarkable preservation of the moraine and other supporting evidence can be attributed to their location on the Kaapvaal craton, one of the planet's most ancient remnants of continental crust. Spanning a staggering age of approximately 3 billion years, this ancient landmass lies beneath a significant portion of South Africa and is speculated to have formed alongside Australia's Pilbara craton, potentially constituting Earth's first continent.
Geologists eagerly engage in debates concerning the exact timing and location of the formation of this initial continent. However, the further we delve into the depths of deep time, the more obscure the available data becomes.
Our comprehension of plate tectonics, the gradual movements of continents across the Earth's surface, also becomes hazier. The coauthors of the recent study on the South African glaciers propose that the region where they discovered the ancient moraine may have, in terms of tectonic activity, been positioned near a pole and constituted part of an ice cap before gradually migrating to its present location over millions of years.

Conclusion

Nevertheless, an alternative hypothesis emerges to explain the existence of these exceptionally ancient glaciers. They could potentially represent the first tangible evidence of a highly debated, elusive concept-the very first "Snowball Earth." This theoretical scenario describes a global deep freeze enveloping nearly the entire planet in a succession of a million or more winters, which would have occurred in the distant past.
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