Continental drift: part of Canada in Australia (Introduction)

by David Turell , Wednesday, January 24, 2018, 00:58 (2496 days ago) @ David Turell

A supercontinent called Nuna existed 1.7 billion years ago and when it broke up a piece of Canada hooked up with Australia. Pangia was a supercontinent 175 million years ago.

http://www.newsweek.com/piece-north-america-found-australia-bolsters-theory-two-billion...

Scientists recently discovered a region of Australia that was once part of North America, bolstering support for the idea that the two existed as a unified 'supercontinent' nearly two billion years ago.

A team led by researchers from Curtin University in Australia discovered that the sedimentary sandstone in the northern Australian region of Georgetown didn't bear much resemblance to other rock compositions in Australia, according to a Curtin University press statement. It did, however, bear quite a strong resemblance to rocks one might find in the North American landmass, known as Laurentia.

This was a critical part of global continental reorganisation when almost all continents on Earth assembled to form the supercontinent called Nuna," co-author Adam Nordsvan, a student at Curtin University's School of Earth and Planetary Sciences, said in the press statement.

The most well-known supercontinent, Pangea, broke apart sometime around 175 million years ago, according to Live Science. But while Pangea may be the most famous, it wasn't the first; a number of supercontinents came before it, including Nuna (sometimes referred to as the Columbia supercontinent).

Nuna itself split into pieces another 300 million years after reaching Australia, according to the statement. But even as the rest of the landmass drifted away, the rock under what would later become Georgetown refused to budge, and has remained part of Australia ever since.

Researchers first started compiling evidence for Nuna's existence in 2002, according to a separate report from Live Science. While the scientific community believed that the landmass under northeast Australia had once been situated by North America, northern China or Siberia, there was never sufficient geological data to prove it. This is a big contribution to the body of evidence supporting Nuna.

“Ongoing research by our team shows that this mountain belt, in contrast to the Himalayas, would not have been very high, suggesting the final continental assembling process that led to the formation of the supercontinent Nuna was not a hard collision like India’s recent collision with Asia,” co-author Zheng-Xiang Li, a John Curtin Distinguished Professor in the School of Earth and Planetary Sciences, said in the press statement. “This new finding is a key step in understanding how Earth’s first supercontinent Nuna may have formed.”

Comment: Our continental crust is light and floats around, and has been doing so for almost two billion years. Continental drift has been an accepted theory for only 60 years, and evidence for Nuna is only 16 years old. A rapid advance for geology. Subduction is vital for the carbon dioxide cycle to exist. It is part of the unique processes that make Earth a special place for life.