Rare metamorphic diamonds discovered could reveal early history of Australia

In collaboration with a colleague from the University of Adelaide, three James Cook University academics have discovered metamorphic diamonds in rocks close to Australia's northeast coast. Alexander Edgar, Ioan Sanislav, Paul Dirks, and Carl Spandler explain how they discovered the small diamonds in their research, which was published in the journal Science Advances. They also explain why they think the discovery will help shed light on Australia's early history and creation.

Diamonds that have undergone metamorphism only occasionally develop in very specific locations. They range in size from microscopic to nanoscale. The rare diamonds are formed at subduction zones, where the pressure of opposing plates grinding against one another over millions of years creates diamonds that are so small that they cannot be seen with the human eye. On Earth, they have only ever been discovered in six other locations. The Clarke River Fault, which formed when crustal blocks were forced together some 500 million years ago, was the site of the majority of them that the researchers discovered in their current investigation.

When one of their students mentioned some rock formations they had seen that appeared to have been exposed when one of the tectonic plates pushed them above the surrounding ground, the researchers started looking into the rocks along the fault line.

According to the researchers, the diamonds they saw were the first to be discovered in the Terra Australis Orogen's Gondwana-Pacific region. Additionally, they assert that since metamorphic diamonds can only be made under extremely precise circumstances, research into them and the places where they are found may help uncover additional details about how Australia was formed.