Possible future scenarios for the subduction zone developing off Spain’s coast. Photo: João Duarte/GeologyOne day we’ll be able to drive from Europe to the Americas. The big question: will there still be human beings alive on the planet when it happens?
Dr João Duarte, from Monash University’s School of Geosciences, has found evidence the ocean floor off the coast of Portugal and Spain is beginning to fracture, signalling the Atlantic is in the early stages of closing.
The fracture is thought to be an embryonic subduction zone – where one of the earth’s massive tectonic plates moves beneath another.
This isn’t just another earthquake, but possibly the beginnings of a new phase in what’s known as the Wilson’s cycle – where oceans close and supercontinents move apart or together again. In this instance, it seems that Europe has started its slow crawl to rejoining the Americas. It will take 20 million years for the fracture to become fully active – and about 220 million years for the reunion of the supercontinents to be complete.
There have been at least three such titanic shifts in the earth’s 4 billion-year history.
The discovery, published in the journal Geology two weeks ago, has created a buzz in the northern hemisphere.
Dr Duarte and his team mapped the underwater faults near Spain and west of Gibraltar – an area known as the south-west Iberia margin.
Historically, the area had suffered massive earthquakes, including the 1755 quake that devastated Lisbon and killed more than 10,000 people. It was suspected the area was a site of “convergent tectonic movement” – and Duarte’s team, for the first time, has found evidence that this is the case.
The evidence is in the form of what’s known as active thrust faults that are occurring off Portugal. They indicate the Eurasian tectonic plate has cracked in what was regarded as a passive area, caused by immense pressures from where Eurasia collides with the African plate to the south.
Dr Duarte said the scientific community had an idea this might have been happening, but there was no evidence.
“What we have achieved is finding this evidence. What we have detected is the very beginnings of an active margin… the plate is breaking in two and beginning to converge,” he said.
This hasn’t been observed before. Normally all evidence of this fracturing – the beginnings of supercontinent movement – is erased by the process.
The original release of this article first appeared on the website of Hangzhou Night Net.Categories : 杭州龙凤