Ancient Diamonds Open a Window on Planet Earth 3.5 Billion Years Ago

Archaean Eon diamonds dug up from ancient rock formations in the Johannesburg area, between 1890 and 1930 – before the industrialisation of gold mining – have revealed secrets of how the Earth worked more than 3.5 billion years ago, confirming that plate tectonics -a key to life- was actively shaping the planet

The three diamonds, which were extracted from the 3 billion-year-old Witwatersrand Supergroup – the rock formation that is host to the famous Johannesburg gold mines – were investigated by Dr. Katie Smart from the University of Alberta and colleagues, to study when modern-style plate tectonics began to operate on planet Earth.

“Because diamonds are some of the the hardest, most robust material on Earth, they are perfect little time capsules and have the capacity to tell us what processes were occurring extremely early in Earth’s history,” says Dr Katie Smart, a Lecturer at the Wits School of Geoscience and the lead researcher on the paper, Early Archaean tectonics and mantle redox recorded in Witwatersrand diamonds, that was published in the journal, Nature Geoscience, in January.


The Earth is approximately 4.5 billion years old, and while a rock record exists from about 4 billion years ago, the complex preservational history of the most ancient rocks exposed on Earth’s surface has led to a heated debate amongst Geoscientists on when plate tectonics began operating on Earth. Many researchers believe plate tectonics began in the Archaean (the Eon that took place from 4 to 2.5 billion years ago), although the exact timing is highly contested.

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