Scientists Rediscover Lost Continent That Broke Off From Australia

Argoland has finally been unearthed.

Lost and Found

About 155 million years ago, the continent of Argoland broke off from its home, the supercontinent Gondwana, drifted to the northwest, and — confoundingly — disappeared. What happened to this lost continent has long been a mystery to geologists.

The main evidence of its existence lies in what's called the Argo Abyssal Plain, a huge basin set deep in the ocean off what is now western Australia, left behind after it separated.

What are essentially geological footprints on the seafloor indicate Argoland waded into Southeast Asia, where it should appear as a large landmass buried beneath the region's islands. Yet no such buried continent has ever been found.

But now, researchers say they've finally discovered its fate. As detailed in a new study published in the journal Gondwana Research, Argoland didn't make its journey in one piece. Instead, it remains as shattered fragments that underlie Myanmar and Indonesia.

It's a bit of a curveball, but the good news is that it's still in Southeast Asia — "otherwise, we would have been faced with a major scientific problem," the researchers said in a statement about the work.

Fraud Continent

The search for Argoland took the researchers more than seven years. "We were literally dealing with islands of information," said coauthor Eldert Avokaat, an earth scientist at Utrech University in the Netherlands, in the statement.

Because Argoland splintered into tiny pieces, it's much harder to trace than a landmass that broke cleanly into huge chunks. When researchers tried to fit the pieces together, none of it made sense.

Then they had their eureka moment: Argoland was actually an "Argopelago."

Long before it ever broke off, the lost landmass began to shatter into microcontinental fragments 300 million years ago, forming an archipelago, or a cluster of islands.

In other words, Argoland was never a single continent. When it eventually parted, its pieces would arrive in Southeast Asia around the same time as one another.

Once there, the lower layers of the "Argopelago" were subducted by the thicker and heavier oceanic crust, while the top of it was deposited onto the crusts of Myanmar and Indonesia.

Picking Up the Pieces

And so, a crisis in geology has been averted. If scientists couldn't find Argoland, it would have had troubling implications on the eventual fate of landmasses.

"If continents can dive into the mantle and disappear entirely, without leaving a geological trace at the earth's surface, then we wouldn't have much of an idea of what the earth could have looked in the geological past," explained study coauthor Douwe van Hinsbergen, a geologist at Utretch, in the statement.

"Those reconstructions are vital for our understanding of processes like the evolution of biodiversity and climate, or for finding raw materials," he added. "And at a more fundamental level: for understanding how mountains are formed or for working out the driving forces behind plate tectonics; two phenomena that are closely related."

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