Study: Earth’s Next Supercontinent Will Assemble when Pacific Ocean Closes in 200-300 Million Years

A team of researchers from Curtin University and Peking University has used a supercomputer to simulate how a supercontinent forms and found that because the Earth has been cooling for billions of years, the thickness and strength of the plates under the oceans reduce with time, making it difficult for the next supercontinent to assemble by closing the young oceans, such as the Atlantic or Indian oceans.

Cartoon illustrating three possible ways of assembling the future supercontinent Amasia from the break-up of Pangaea (a-b): (c) extroversion, (d) orthoversion, (e) introversion. Image credit: Huang et al., doi: 10.1093/nsr/nwac205.

A primary feature of Earth’s tectonic evolution is the supercontinent cycle since around 2 billion years ago, featuring a cyclical assembly and dispersal of major continents with a periodicity of around 600 million years.

Two endmember forms of supercontinent assembly have been proposed: introversion or extroversion assembly.

The former involves the closure of internal oceans created during the break-up of the previous supercontinent, whereas the latter involves the closure of the external superocean surrounding the previous supercontinent.

Of the three known supercontinents, the oldest one — Nuna/Columbia (existed 1.6-1.3 billion years ago) — could be Earth’s first supercontinent, and its assembly therefore does not involve the introversion/extroversion processes.

However, how the two younger supercontinents — Rodinia (900-700 million years ago) and Pangea (320-170 million years ago) — formed remains controversial.

“Our new findings are significant and provide insights into what would happen to Earth in the next 200 million years,” said Dr. Chuan Huang, a researcher in the Earth Dynamics Research Group and the School of Earth and Planetary Sciences at Curtin University and the Key Laboratory of Orogenic Belts and Crustal Evolution at Peking University.

“Over the past two billion years, Earth’s continents have collided together to form a supercontinent every 600 million years, known as the supercontinent cycle.”

“This means that the current continents are due to come together again in a couple of hundred of million years’ time.”

The resulting new supercontinent has already been named Amasia because some believe that the Pacific Ocean will close — as opposed to the Atlantic and Indian oceans — when America collides with Asia.

Australia is also expected to play a role in this important Earth event, first colliding with Asia and then connecting America and Asia once the Pacific Ocean closes.

“By simulating how the Earth’s tectonic plates are expected to evolve using a supercomputer, we were able to show that in less than 300 million years’ time it is likely to be the Pacific Ocean that will close, allowing for the formation of Amasia, debunking some previous scientific theories,” Dr. Huang said.

The Pacific Ocean is what is left of the Panthalassa superocean that started to form 700 million years ago when the previous supercontinent started to break apart.

It is the oldest ocean we have on Earth, and it started shrinking from its maximum size since the dinosaur time.

It is currently shrinking in size by a few centimeters per year and its current dimension of about 10,000 km is predicted to take two to three hundred million years to close.

“Having the whole world dominated by a single continental mass would dramatically alter Earth’s ecosystem and environment,” said Professor Zheng-Xiang Li, a researcher in the Earth Dynamics Research Group and the School of Earth and Planetary Sciences at Curtin University.

“Earth as we know it will be drastically different when Amasia forms.”

“The sea level is expected to be lower, and the vast interior of the supercontinent will be very arid with high daily temperature ranges.”

“Currently, Earth consists of seven continents with widely different ecosystems and human cultures, so it would be fascinating to think what the world might look like in 200 to 300 million years’ time.”

The team’s paper was published in the National Science Review.

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Chuan Huang et al. Will Earth’s next supercontinent assemble through the closure of the Pacific Ocean? National Science Review, published online September 28, 2022; doi: 10.1093/nsr/nwac205