Two sunken islands discovered near Australia

Two sunken islands discovered near Australia

In the remote waters of the Indian Ocean, west of Perth, scientists have just discovered two sunken islands, almost the size of Tasmania, which were once part of the supercontinent Gondwana.

 The islands were found during a three-week voyage to map the seafloor of the Perth Abyssal Plain that concluded last week. The researchers who found the islands believe that they were once part of the ancient supercontinent of Gondwana. New discovery could have ramifications for our understanding of how that giant landmass once broke apart.

Islands discovered near Australia

Commonwealth Scientific and Industrial Research Organisation (CSIRO) vessel Southern Surveyor discovered the islands through detailed seafloor mapping and by dredging rock samples from the steep slopes of the two islands that now are covered by about a mile (1.5 kilometers) of ocean water. 

The sunken islands charted during the expedition have flat tops, which indicates they were once at sea level before being gradually submerged.  Researchers retrieved continental rocks such as granite, gneiss and sandstone containing fossils which indicate that the islands weren't underwater in history.

The sunken islands charted during the expedition have flat tops, which indicates they were once at sea level before being gradually submerged.  Researchers retrieved continental rocks such as granite, gneiss and sandstone containing fossils which indicate that the islands weren't underwater in history.

The rocks formation suggests how the islands might have fit into the breakup of Gondwana: In the Cretaceous period when dinosaurs roamed the Earth (more than 130 million years ago), India was adjacent to Western Australia. When India began to break away from Australia, the islands formed part of the last link between the two continents. Scientists reffered these islands as "micro-continents" which were eventually separated from both landmasses and stranded in the Indian Ocean, thousands of miles from the Australian and Indian coasts.

"The data collected on the voyage could significantly change our understanding of the way in which India, Australia and Antarctica broke off from Gondwana," said team member Joanne Whittaker, a postdoctoral fellow at the University of Sydney.

A more detailed analysis of the rocks dredged up during the voyage will tell about their age and how they fit into the Gondwana jigsaw. The implications of the detail to be found from these islands goes beyond a finer-tuned picture of Gondwana's dismantling.

"Our preliminary analysis of the magnetic data that we collected could cause us to rethink the whole plate tectonic story for the whole of the eastern Indian Ocean," Whittaker said.


Eastern Gondwana

The expedition took place aboard the Marine National Facility's Research Vessel Southern Surveyor, which is owned and managed by the Commonwealth Scientific and Industrial Research Organisation. Researchers from Macquarie University and the University of Tasmania also participated in the expedition. (UniversityOfSidney)

Comments

katesisco 8 years ago

The Galapagos is only a few million years old. Cyprus was part of the Levant. Crete pulled of the lower Levant and sped west. The Isthmus of Panama was part of the Pacific ocean floor. I am considering whether the Mayan Peninsula was split and driven apart or just plain vaporized. Since all this topsy-turvy work has gone on in plain sight and we fail to interpret it, maybe we should just go with the simplest option; that Earth is not Earth at all but water, and since water wants to be ice, we should rename Earth Ice.

TheWatchers Adorraeli on Facebook 8 years ago

well the article says almost the size of Tasmania

Sonia Riley on Facebook 8 years ago

How large are they

Chillymanjaro (@Sonia Riley on Facebook) 8 years ago

well, for now that's the information of our interest too, but no oficial numbers, just comparison that it is the size of Tasmania. At its longest point, the Australian state of Tasmania is 296km from north to south, whilst at its widest point east to west, Tasmania measures 315km. The area of Tasmania is 68,119 square kilometres so it's somewhere in that parameters.

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