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article imageNorth America will collide with Europe in 220 million years

By Jordan Howell     Jun 19, 2013 in Science
Geologists from Monash University have discovered a new subduction zone just off the coast of Portugal that will pull Europe and North America together into a single continent and spell the end of the Atlantic Ocean as we know it—in 220 million years.
The new research, published in the June 6 issue of the journal Geology, is the first evidence that the passive margin separating the Atlantic’s oceanic crust from mainland Europe has activated due to pressure from tectonic convergence on the southern boundary of the Eurasian plate.
The Atlantic Ocean is surrounded by what are known as passive margins, or boundaries between sections of Earth’s crust where an ancient and inactive tectonic rift has been covered with millions of years of sediment, in this case a result of the divergence of the North American and Eurasian plates at the Mid-Atlantic Ridge.
By דקי (Own work) [CC-BY-SA-3.0 ( or GFDL (http://w
Dr João Duarte and his team from the Monash School of Geosciences based in Melbourne, Australia discovered fractures along the ocean floor, indicating tectonic activity near the seemingly passive South West Iberia plate margin.
“What we have detected is the very beginnings of an active margin - it's like an embryonic subduction zone," Dr Duarte said. "Significant earthquake activity, including the 1755 quake which devastated Lisbon, indicated that there might be convergent tectonic movement in the area. For the first time, we have been able to provide not only evidences that this is indeed the case, but also a consistent driving mechanism."
Subduction zones are active tectonic boundaries where one plate dives beneath another into the mantle, or the layer of molten rock that lies between the crust and the outer core.
Passive margins between oceanic and continental crust have been known to spontaneously change into active tectonic boundaries, but this process is not very well understood.
Scientists have long thought that passive margins may spontaneously become active due to the pressure of the sediment along the ancient rift.
However, Dr. Duarte’s research suggests that this activation is actually caused by pressure from a nearby tectonic collision zone.
This discovery offers scientists the unique opportunity to study the activation of a passive margin, which should take approximately 20 million years.
"Understanding these processes will certainly provide new insights on how subduction zones may have initiated in the past and how oceans start to close," Dr Duarte said.
Ultimately, this could mark the beginning of a new phase in Earth’s evolution, as the continents, which broke apart 200 million years ago, begin their long slow migration back into a new Pangaea.
More about Plate tectonics, tectonic plates, Europe, North America, passive margin
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