Researchers uncover piece of North America in Australia
25 January 2018
Geologists who matched rocks from opposite sides of the globe have discovered that part of Australia was once attached to North America 1.7 billion years ago.
Researchers from Curtin University in Australia examined rocks from the Georgetown region of northern Queensland.
The rocks that are sandstone sedimentary were formed in a shallow sea have signatures that were now known in Australia but strongly resembled rocks that can be seen in present-day Canada.
The researchers, who described their findings online today in the journal Geology, concluded that the Georgetown area broke away from North America 1.7 billion years ago and one hundred million years later, the landmass collided with what is now northern Australia at the Mount Isa region.
"This was a critical part of global continental reorganization when almost all continents on Earth assembled to form the supercontinent called Nuna," Adam Nordsvan, a Curtin University doctoral student and lead author of the study, said.
According to Nordsvan, Nuna then broke apart some 300 million years later, with the Georgetown area stuck to Australia as the North American landmass drifted away.
"This was a critical part of global continental reorganization when almost all continents on Earth assembled to form the supercontinent called Nuna," Nordsvan said.
The findings suggest that a part of northern Australia was actually part of North America 1.7 billion years ago.
Nordsvan said the findings were significant as they unlock important information about the 1.6 billion year old supercontinent Nuna.
"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. Georgetown then broke away from North America and collided with the Mount Isa region of northern Australia around 100 million years later,'' Nordsvan said.
''This was a critical part of global continental reorganisation when almost all continents on Earth assembled to form the supercontinent called Nuna.''
''The team was able to determine this by using both new sedimentological field data and new and existing geochronological data from both Georgetown and Mount Isa to reveal this unexpected information on the Australia continent.''
''Researchers then determined that when the supercontinent Nuna broke apart an estimated 300 million years later, the Georgetown area did not drift away and instead became a new piece of real estate permanently stuck to Australia.''
Co-author John Curtin Distinguished professor Zheng-Xiang Li, also from Curtin's School of Earth and Planetary Sciences, said the research also revealed new evidence of mountains being built in both the Georgetown region and Mt Isa when Georgetown collided with the rest of Australia.
''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,'' professor Li said.
''This new finding is a key step in understanding how Earth's first supercontinent Nuna may have formed, a subject still being pursued by our multidisciplinary team here at Curtin University.''
''The research was co-authored by researchers from Curtin University, Monash University, and the Geological Survey of Queensland.''