|Photo: The Sun|
Researchers uncovered traces of a lost continent that disappeared under what is today Europe about 120 million years ago.
THE HISTORY of a lost continent buried under Europe for 100million years has been revealed for the first time. Greater Adria was a giant landmass the size of Greenland that dramatically collided with our own continent.
The crash ploughed most of Greater Adria under the ground and sea while the rest crumbled into rocks on land. Remnants of the geological blow remain millions of years later, say an international team of scientists.
They analysed rocks that were originally part of Greater Adria found in mountain ranges stretching from Spain to Iran. A lengthy paper penned by the group gives a blow-by-blow account of the Earth's geological history stretching back 240million years.
Hinsbergen and his team spent a decade collecting and analyzing rocks that used to be part of this ancient continent. The mountain belts where these Greater Adrian rocks are found span about 30 different countries, Hinsbergen told Live Science. "Every country has their own geological survey and their own maps and their own stories and their own continents," he said. With this study, "we brought that all together in one big picture."
Around 100 million to 120 million years ago, Greater Adria smashed into Europe and began diving beneath it — but some of the rocks were too light and so did not sink into Earth's mantle. Instead, they were "scraped off" — in a way that's similar to what happens when a person puts their arm under a table and then slowly moves it underneath: The sleeve get crumpled up, he said. This crumpling formed mountain chains such as the Alps. It also kept these ancient rocks locked in place, where geologists could find them.
Hinsbergen and his team looked at the orientation of tiny, magnetic minerals formed by primeval bacteria in these rocks. The bacteria make these magnetic particles in order to orient themselves with the Earth's magnetic field. When the bacteria die, the magnetic minerals are left behind in the sediment, Hinsbergen said.
With time the sediment around them turns into rock, freezing them in the orientation they were in hundreds of millions of years ago. Hinsbergen and his team found that in many of these regions, the rocks had undergone very large rotations.
What's more, Hinsbergen's team pieced together large rocks that used to belong together, such as in a belt of volcanoes or in a big coral reef. Moving faults scattered the rocks "like pieces of a broken plate," he said.
It's like a big jigsaw puzzle, Hinsbergen said. "All the bits and pieces are jumbled up and I spent the last 10 years making the puzzle again." From there, they used software to create detailed maps of the ancient continent and confirmed that it moved northward while twisting slightly, before colliding with Europe.
After many years working in the Mediterranean region, Hinsbergen has now moved on to reconstruct the lost plates in the Pacific Ocean. "But I'll probably return — probably in 5 or 10 years from now when a whole bunch of young students will demonstrate that parts are wrong," Hinsbergan said. "Then I'll come back and see if I can fix it."
The study was published in the journal Gondwana Research.