Curtin researchers discover a piece of America in northern Australia

Curtin University researchers have discovered rocks in northern Queensland that bear striking similarities to those found in North America, suggesting that part of northern Australia was actually part of North America 1.7 billion years ago.

The research paper in GEOLOGY published by the Geological Society of America, concluded that the rocks found in Georgetown, 412 kilometres west of Cairns, have signatures that are unknown in Australia and instead have a surprising resemblance to rocks found in Canada today.

Curtin University PhD student Adam Nordsvan from the School of Earth and Planetary Sciences 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,” Mr 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.”
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dv said:

Curtin researchers discover a piece of America in northern Australia

Curtin University researchers have discovered rocks in northern Queensland that bear striking similarities to those found in North America, suggesting that part of northern Australia was actually part of North America 1.7 billion years ago.

The research paper in GEOLOGY published by the Geological Society of America, concluded that the rocks found in Georgetown, 412 kilometres west of Cairns, have signatures that are unknown in Australia and instead have a surprising resemblance to rocks found in Canada today.

Curtin University PhD student Adam Nordsvan from the School of Earth and Planetary Sciences 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,” Mr 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.”
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It has been thought for a good few years that the Georgetown Terrane might not have had its origin adjacent to the Mt Isa block. The beauty of this work is that the researchers used the age spectrum of detrital zircons to show that they did not originate in Australia, but rather, they likely originated in North America.

dv said:

Curtin researchers discover a piece of America in northern Australia

Curtin University researchers have discovered rocks in northern Queensland that bear striking similarities to those found in North America, suggesting that part of northern Australia was actually part of North America 1.7 billion years ago.

The research paper in GEOLOGY published by the Geological Society of America, concluded that the rocks found in Georgetown, 412 kilometres west of Cairns, have signatures that are unknown in Australia and instead have a surprising resemblance to rocks found in Canada today.

Curtin University PhD student Adam Nordsvan from the School of Earth and Planetary Sciences 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,” Mr 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.”
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Only a couple of weeks ago I replied at length to this post. In chat?

To greatly summarise.

• 1.6 billion years was a very long time ago
• It looks reasonable
• The method would work well with sedimentary and metamorphic rocks but not igneous rocks
• North America has two separate terrains from prior to this era, it’s not immediately clear why the Georgetown rocks are an equal mixture of the two
• I included a link to the original research paper.

This time I didn’t find a link to the free article. But the abstract is:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/526080/laurentian-crust-in-northeast-australia
I suspect that the article was initially released free to view and has since switched to pay to view.

This older article about Australia and Nuna has some really pretty pictures in it.
http://www.academia.edu/download/40976157/Betts_et_al_2015_GSLSP.pdf

So does this one:
http://52.172.159.94/index.php/epi/article/download/59883/46840

Both of the older articles leave the situation of Georgetown as a question mark, suggesting perhaps that the centre rather than the north of the Queensland seaboard was hard up against North America.