Superdeep diamonds: ancient diamonds may give clues about Earth's origins

A new discovery of ancient diamonds has provided new clues about the Earth's evolution, after they were found deep in the mines of Brazil and Western Africa, and dated between 650 and 450 million years ago, at the base of the supercontinent Gondwana.

A team of international experts discovered the diamonds and said they shed light on the evolution and movement of Earth’s continents during the early stages of complex life. Diamonds, which are known for their extraordinary resilience, can serve as records of ancient cycles of the creation and destruction of continents, but researchers say this particular type is “extremely rare."

Dr Karen Smit, of the Wits School of Geosciences said: "We now know that they can tell us a lot about the entire process of continent formation. Diamonds formed at great depths beneath Gondwana when the supercontinent covered the South Pole, between 650–450 million years ago.

"Approximately 120 million years ago, Gondwana commenced its fragmentation, ultimately giving rise to the present-day oceans, including the Atlantic. Some 90 million years ago, the diamonds, bearing tiny inclusions of the host rock, were brought to the Earth’s surface through violent volcanic eruptions."

The study involved dating the tiny silicate and sulphide inclusions within the diamonds to help figure out how they formed beneath the Gondwana supercontinent - and in the process revealed how modern day continents may have been formed.

The rocks featuring the diamonds became buoyant during the diamond formation process, carrying subducted mantle material along with the diamonds, which was then integrated into the base of the Gondwana supercontinent, contributing to its growth from below and subsequent fragmentation to create new continents.

The volcanic eruptions that brought the diamonds to the surface are situated Brazil and Western Africa, which are two significant components of the former Gondwana supercontinent, indicating the rare diamonds moved along different parts of the ancient supercontinent as it pulled apart, effectively “glued” to its base, according to the researchers.

Dr Smit added: “This intricate history of the diamonds underscores their extensive travels, both vertically and horizontally, within the Earth. They provide insights into the formation of the supercontinent and its later stages of evolution. This suggests a potential new mode of continent growth, where relatively young material fuses and consolidates these age-old continental fragments.

"We need this type of research to understand how continents evolve and move. Without continents, there wouldn’t be life. This research gives us insight into how continents form and how life evolved, ultimately highlighting what makes our planet, Earth, unique among celestial bodies."