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Lost continent revealed in new reconstruction of geological history



Take a walk along the mountain belts scattered across the Adriatic Sea, so you may find yourself climbing over the crumpled remains of a long-lost continent.

crust torn millions of years ago, researchers report this month in the journal Gondwana Research . The story of the continent's demise is part of a new report that re-creates the last 240 million years of Mediterranean tectonic history in outstanding detail.

The model shows how this continent was first separated from what is now Spain, southern France, and northern Africa and forms a separate landmass that the team has formally called Greater Adria. But as the rocky plates of the planet continued to try relentlessly, this continent tumbled into several subduction zones, the earth's destructive geological pits. (Find out what might happen when the tectonic plates of the earth grind to a halt.)

As it faded into the sacred depth of the mantle, the upper layer of the continent was scraped away, as if a titanium were peeling a colossal apple. This wreck was dumped on the overlying plates, ready to form future mountains along Italy's backbone, as well as in Turkey, Greece, the Alps and the Balkans.

Several rivers on the continent avoid both neat shaving and slow erosion through subduction. These unsorted relics from Stora Adria are found today on the heels of Italy's luggage, spread from Venice to Turin and in Croatia's Istria region ̵

1; which means you can take a vacation on splinters on a lost continent.

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Rebuilding this piece of our geological past is key to understanding the present, says study leader Douwe van Hinsbergen, an expert on tectonics and ancient geography at Utrecht University.

"Everything you see around you that was not wood or fabric was found by a geologist in a mountain," he says. Ores, metals and minerals that are now vital to civilization can be found within these peaks, and over time interconnected caches of them have been fragmented by plate tectonic pandemonium.

Models such as the one in the new study can allow us to rewind the clock and see this dissection take place. For example, if copper storage is found in a country, such reconstructions allow us to calculate where its once-connected inserts may have ended up, effectively creating tax maps of modern times.

Rereading the puzzle [19659012] Restoration of the geological development of the Mediterranean since the Triassic period posed some serious challenges. Scientists have had a broad understanding of the region's tectonic history for a long time, but the labyrinthine geological puzzle made a more detailed analysis daunting.

"The Mediterranean is a dog breakfast," says Robert Stern, a plate actonics expert at the University of Texas at Dallas who was not involved in the work.

Within this troubled region, several geologists had previously found clues to the existence of a lost continent, but important details in its narrative proved difficult to capture. The remains are scattered over 30 countries, each with their own models, maps, survey techniques and terminologies. The continent even had a number of possible names in the literature.

To sort things out, the team spent ten years gathering a stream of geological and geophysical data from across the region and connecting them to their model using a software called GPlates. Over the past 15 years, this software, which van Hinsbergen describes as "relatively idiot-proof", has enabled more detailed visualization and adjustment of flat tectonic systems. The careful process of the team revealed the missing chapters of the lost continent's tangled tour.

About 240 million years ago, Greater Adria was part of the Pangea supercontinent, crushed against what is now northern Africa, Spain and southern France. It broke away from Africa 20 million years later, and then separated from France and Spain 40 million years after that to become an isolated continent.

Although its geography remains unclear at the moment, it was probably a bit like the largely submerged continent of Zealandia, with bits of land (in this case New Zealand and New Caledonia) sticking out from the sea. It may also have been much like the Florida Keys, with an archipelago of non-volcanic islands perched above the waves.

Monumental Effort

The destruction of Greater Adria began in earnest 100 million years ago, when it encountered what is now southern Europe and parts of the dove under a series of plates throughout the region. This widespread subduction of the continent meant that "every little piece had its own history," says van Hinsbergen. "And then you end up with the mess that is now the Mediterranean."

But crucially, "if continents disappear, they tend to leave marks," van Hinsbergen says, and that includes scars from mountain building. [19659002] You can make mountains when two continents collide, like what happened to form the Himalayan mountain range. But you don't always need a collision zone to make mountains. Removing plates can also have their top layers scraped off the top plate, says Stern, and these scrapers can be accumulated and crushed to form rocks. (Also find out what happens in the rare case of an oceanic plate scaling apart.)

This principle was crucial for reconstructing the Mediterranean past, says van Hinsbergen. Geologists can match the amount of rock building remains seen today to the length of the part of the original slab that has been swallowed into the underlying mantle, allowing them to more accurately model the pieces of the ancient puzzle.

the work has "clearly been a monumental undertaking," says geophysicist Dietmar Müller, co-chair of the EarthByte project at the University of Sydney, the research team that developed GPlates. The effort that went into it is comparable to that involved in his own group restoring the entire planet's tectonic narrative – but what this new work loses on a pure scale, he says, it does up with breathtaking details.


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