Scientists have found evidence of a lost continent that moved away from the landmass that became Australia 155 million years ago.
Geologists have long believed that Argoland existed because of a huge cavity in Western Australia, but until now the evidence was circumstantial.
A team from Utrecht University in the Netherlands reconstructed the history of Argoland and determined that the 3,100-mile-long piece of land had made its way to South Asia and now lies more than 18,000 feet below the surface of the Indian Ocean.
Magnetic and structural geological evidence along the local seafloor suggests that the giant fragment separated by shifting tectonic plates that make up the Earth’s crust before drifting north and west toward Southeast Asia.
Scientists have found evidence of a lost continent that moved away from the landmass that became Australia 155 million years ago
By reconstructing the history of the lost continent, the team concluded that it expanded into South Asia
Eldert Advokaat, from the Department of Geosciences at Utrecht University, said: “The situation in Southeast Asia is very different to places like Africa and South America, where a continent broke cleanly in two.” Argoland shattered into many different shards.
“That blocked our view of the journey of the continent.”
Researchers used computer reconstruction based on existing geological evidence to paint a picture of how Argoland broke up into several pieces and settled around what is now Indonesia and Myanmar.
Instead of a single landmass, they found many smaller pieces that came together over millions of years.
By solving this mystery, geologists have filled a significant gap in our knowledge and added new context to the evidence about how mountains, islands and underwater geology were formed.
The continent of Argoland broke away from Australia millions of years ago and migrated northwest, but its final home was previously unknown.
The existence of Argoland was hinted at by a void in Western Australia called the Argo Abyssal Plain. The fragments of Argoland were found in what is now Southeast Asia
By reviewing the architecture of known tectonic “megaunits” in Southeast Asia and northwest Australia, the team pieced together scattered remnants of what once comprised Argoland and suggested how they came to be so far from their original location.
During the Late Jurassic Period, 164 to 145 million years ago, the vast landmass of Pangea broke up into two supercontinents: Laurasia and Gondwana. However, the break wasn’t entirely clean.
It appears that by this time Argoland had already split into several continental fragments and sections of seafloor.
The islands of Argoland’s apparent destination do not appear to be on anything resembling the theoretical continent. The only pieces of ancient continental crust in the region were much older, about 205 million years old, according to radiological dating.
A team from Utrecht University reconstructed the history of Argoland and determined that the 3,100-mile-long piece of land had made its way to South Asia and now lies more than 18,000 feet below the surface of the Indian Ocean
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One possibility was that the continent had slipped beneath a subduction zone – areas where one tectonic plate meets another and slides beneath the neighboring plate.
At these junctions, rocky ocean floors will reconnect with the Earth’s mantle beneath the Earth’s crust, where they will re-melt into magma and form crust at some point in the future.
Given the age difference between the Argo Abyssal Plain and these possible fragments, researchers suspected that the fragments may not have come from Argoland.
They may have migrated there long before Argoland slipped beneath a subduction zone.
Based on the team’s reconstruction, these fragments migrated across the Indian Ocean over the millions of years between then and now.
Although geologists write that the fragments are “severely deformed,” they still exist.
They settled in what are now jungle-covered areas in Myanmar on the Asian mainland and on several islands in the Indonesian archipelago.
The researchers note some limitations to their reconstruction.
Many of the estimated geologic ages of tectonic plate sections are based on ancient data, so modern measurements may prove more accurate.
“The dense vegetation cover and seas in the area we reconstructed complicated our correlations and they may not always be accurate,” the researchers added.