Collapse of Earth’s tectonic plates unravelled

Following the international expedition drilling into the Pacific ocean floor, the scientists have for the first time discovered what happens after one tectonic plate gets pushed under another, Australian National University reports.

During the drilling expeditions, researchers uncovered distinctive rocks, thought to have formed when the Pacific tectonic plate changed direction and began plunging under the Philippine Sea Plate about 50 million years ago.

"It's a bit like a rugby scrum, with two rows of forwards pushing on each other. Then one side goes down and the other side goes over the top," said study leader Professor Richard Arculus, from the Research School of Earth Sciences

"But we never knew what started the scrum collapsing," added Professor Arculus.

The newly gathered data could help scientists in understanding the huge earthquakes and volcanoes that form in places of plates collision when one plate gets pushed under the other.

As part of the International Ocean Discovery Program, the team studied the sea floor in 4 700 metres (2.9 miles) of water in the Amami Sankaku Basin of the north-western Pacific Ocean, near the Izu-Bonin-Mariana Trench, which forms the deepest parts of the Earth's oceans.

Research team has drilled 1 600 meters (0.9 miles) deep into the sea floor to collect rock types from the extensive rifts and big volcanoes. initiated during the subduction of one plate under the other.

"We found rocks low in titanium, but high in scandium and vanadium, so the Earth's mantle overlying the subducting plate must have been around 1,300 degrees Celsius and perhaps 150 degrees hotter than we expected to find," Professor Arculus said.

The team found the tectonic scrum collapsed at the south end first and then the Pacific Plate rapidly collapsed 1 000 kilometres (621.4 miles) northwards in about one million years.

"It's quite complex. There's a scissoring motion going on. You'd need skycam to see the 3D nature of it," Professor Arculus said.

Professor Arculus said that the new knowledge could give insights into the formation of copper and gold deposits that are often formed where plates collide.

Featured image: Professor Richard Arculus. Image credit: Charles Tambiah and MNF