An international team studied superdeep diamonds that formed between 650 and 450 million years ago, revealing insights into how continents form and move, as well as Gondwana's history. These diamonds were formed during the Gondwana supercontinent era, shedding light on supercontinent formation and mobility.
They serve as valuable records of Earth's evolution and the supercontinent cycle. By dating tiny inclusions in these diamonds, researchers traced the material added to Gondwana's keel, uncovering previously unknown geological processes.
Diamonds and the Supercontinent Cycle
Ancient diamonds, created millions to billions of years ago, provide a unique perspective on the Earth's most profound geological processes. They serve as a historical record, shedding light on the cycles of supercontinents, which form and disintegrate over time.
Supercontinents have the potential to concentrate the subduction of oceanic plates, a critical mechanism driving plate tectonics. However, investigating these deep geological phenomena directly has proven challenging due to the relative youth of oceanic crust and the limited insights offered by continental crust.
To address this conundrum, a team led by Dr. Suzette Timmerman from the University of Bern in Switzerland embarked on a study of these ancient diamonds. Their primary aim was to gain an understanding of how materials were integrated into the keel of supercontinents.
Throughout this inquiry, they stumbled upon a previously unknown geological process, which has been detailed in a publication in the journal Nature. Their comprehensive analyses, which involved dating the diamonds, combined with existing models of plate tectonics and continent migration, have unveiled the diamonds' formation at great depths below Gondwana.
These findings suggest that the diamonds originated beneath Gondwana while the supercontinent was situated at the South Pole, approximately between 650 and 450 million years ago. This remarkable discovery provides crucial insights into the Earth's deep-seated geological mechanisms and their relation to the supercontinent cycle, which encompasses the continual formation and dissolution of supercontinents.
The exceptional durability of diamonds has enabled them to preserve a historical record of these ancient geological events, offering a valuable window into our planet's distant past.
Diamonds: A Perfect Time Capsule
Superdeep diamonds, which hail from depths of 700 kilometers or more in the Earth, serve as invaluable research materials due to their remarkable properties. Suzette Timmerman, an assistant professor of geology from the University of Bern, said in a news release that diamonds are chemically inert and act as perfect time capsules, preserving a record of geological processes.
These diamonds offer unique insights into deep plate tectonic cycles that control essential Earth processes, such as the carbon cycle and carbon sequestration into the mantle. They have the capability to reveal details about the Earth's depths that are otherwise inaccessible.
Host rocks containing these superdeep diamonds were buoyant during their formation and carried subducted mantle material and the diamonds to a keel-like structure at the base of the Gondwana supercontinent, contributing to the continent's growth from below.
Around 90 million years ago, these diamonds reached the Earth's surface through violent volcanic eruptions in regions of Brazil and Western Africa, key components of Gondwana. The journey of the diamonds alongside various parts of the ancient supercontinent during its dispersal to form contemporary continental landmasses can be inferred.
Exploring deep plate tectonic cycles remains challenging due to the difficulty of obtaining samples from the Earth's mantle. The inclusions observed in superdeep diamonds are rare and elusive, demanding extensive microscopic examination.
This study involved collaboration with multiple researchers who contributed inclusions from their collections. Analyzing these minute materials with the aid of advanced analytical techniques provided valuable insights into the Earth's deep geological processes.
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