Metamorphic diamond from the northeastern margin of Gondwana: Paradigm shifting implications for one of Earth’s largest orogens

Diamonds provide a glimpse into Australia’s geological past

31 October 2022

The discovery of tiny diamonds embedded in rock samples from northeastern Australia indicates that the geological past Australia’s eastern coast is more complex than previously thought.

Metamorphic rocks form when rocks are subjected to high temperatures or pressures. Sometimes small diamonds also form under these conditions, but so far such metamorphic diamonds have only been discovered in six locations in the world. They are formed in places where one tectonic plate slides under another one.

Now, a team led by a researcher from the University of Adelaide in Australia has found metamorphic diamonds in an area that was once the northeastern corner of Gondwana — the massive landmass that became Australia.

This discovery allowed the team to revise estimates of the minimum pressure and temperatures the rocks were subjected to. Their estimates indicate that they couldn’t have formed through accretionary processes alone.

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References

1. Science Advances 8, eabo2811 (2022). doi: 10.1126/sciadv.abo2811