Telltale rocks suggest that part of Australia was once part of North America
Also known as Columbia, Nuna was a supercontinent that geologists believe existed from approximately 2.5 to 1.5 billion years ago. Now, there's new evidence as to how its various pieces once fit together – Australian scientists have found rocks in northern Queensland, that match up with rocks from Canada.
The rocks, which have geological signatures that are unknown anywhere else in Australia, were found near the small town of Georgetown, which is located about 412 km (256 miles) west of Cairns. They are said to be very similar to rocks that are currently found in Canada's precambrian shield.
"Our research shows that about 1.7 billion years ago, Georgetown rocks were deposited into a shallow sea when the region was part of North America," says lead scientist Adam Nordsvan, a PhD student from Australia's Curtin University. "Georgetown then broke away from North America and collided with the Mount Isa region of northern Australia around 100 million years later. This was a critical part of global continental reorganization when almost all continents on Earth assembled to form the supercontinent called Nuna."
It is now believed that when Nuna broke apart an estimated 300 million years later, the Georgetown area remained permanently stuck to the rest of Australia. This runs counter to an existing theory, which states that Georgetown had been a part of Australia all along.
A paper on the findings was recently published in the journal Geology. Also taking part in the research were scientists from Monash University and the Geological Survey of Queensland.
Source: Curtin University