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- Geologists prospecting for oil in the
Barents Sea have stumbled across the largest meteorite crater ever found
in Europe. It is also one of the largest in the world.
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- It was formed 150 million years ago when
an asteroid, possibly 500m across and travelling at 30,000 km/h, plunged
into the sea off the coast of Norway.
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- It would have caused worldwide devastation
resulting in global climate change and the extinction of many species.
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- At the site of the impact there would
have been a mushroom cloud of superheated steam. Temperatures of over 10,000
degrees centigrade would have melted many tonnes of rock. Gigantic tidal
waves would then have raced around the world from Canada to Russia.
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- After the initial fury, dust and other
particles thrown into the atmosphere would have created a cloud that blocked
out the sunlight starting a "nuclear winter".
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- Many species not wiped out by the initial
impact would have died out during the prolonged cold and lack of sunlight
in this extended winter.
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- Accidental discovery
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- The discovery of the crater in the Barents
Sea was accidental, following a search for potential oil and gas reservoirs.
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- At first geologists thought it was an
ordinary salt formation or a submarine volcano. But Steinar Gudlauggson,
from the Department of Geology at the University of Oslo, had suspicions
that it was an impact crater.
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- Geologists looked at the data more closely
and concluded that it could be a parallel to the Chicxulub Crater in Mexico,
the imprint left by the meteorite which caused the extinction of the dinosaurs.
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- Intense deformation
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- The proof came after the examination
of rock samples drilled from close to the crater. They studied 400,000
quartz grains and found they had been deformed by an intense, sudden shock
wave.
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- They also found traces of the rare element
iridium which is far more common in objects from space than on the Earth's
surface.
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- One of the drilled rock cores, 121 m
long, has been described as a geological gem. It is one of the few cases
where both the crater and the dust and rock blasted out by the impact have
been found and collected. The crater rock and the debris on top therefore
carry unique information about the impact.
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- Although the Earth has suffered a steady
bombardment from space over geological time, only 160 impact craters have
been identified. The Mjølnir crater is only the seventh marine meteor
crater found.
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- Most craters on land have been eroded
away. This makes a well-preserved undersea crater particularly valuable
to scientists.
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