Why some plate break-ups are fierier than others
But a new study has shown that this isn’t always the case – and also
explained why not.
When what is now the continent of North America broke away from what went on to become Europe 54 million years ago, it led to a series of massive volcanic eruptions along the resulting rift. However, a team of scientists has shown that when a similar rupture took place between the Indian subcontinent and what is now the Seychelles 63 million years ago, it took place with the equivalent of a volcanic whimper.
According to the researchers, the difference lay in the prior history of the rift. In the case of the break-up of North America and Europe, a previous geological event had thinned the plate, providing a focal point where the mantle beneath the plate could melt rapidly, forming magma that erupted through the thinned plate. In comparison, the region around the Seychelles had experienced volcanic activity in a neighbouring area called the Gop Rift six million years earlier, so when the plates broke apart, the supply of magma was reduced, and there was little left to erupt.
‘Our study is helping us to see that the history of the rift is really important for determining the level of volcanic activity when plates break apart,’ said the study’s lead author, John Armitage of Imperial College London. ‘We now know that this rift history is just as important as mantle temperature in controlling the level of volcanic activity on the Earth’s surface.’
August 2010
When what is now the continent of North America broke away from what went on to become Europe 54 million years ago, it led to a series of massive volcanic eruptions along the resulting rift. However, a team of scientists has shown that when a similar rupture took place between the Indian subcontinent and what is now the Seychelles 63 million years ago, it took place with the equivalent of a volcanic whimper.
According to the researchers, the difference lay in the prior history of the rift. In the case of the break-up of North America and Europe, a previous geological event had thinned the plate, providing a focal point where the mantle beneath the plate could melt rapidly, forming magma that erupted through the thinned plate. In comparison, the region around the Seychelles had experienced volcanic activity in a neighbouring area called the Gop Rift six million years earlier, so when the plates broke apart, the supply of magma was reduced, and there was little left to erupt.
‘Our study is helping us to see that the history of the rift is really important for determining the level of volcanic activity when plates break apart,’ said the study’s lead author, John Armitage of Imperial College London. ‘We now know that this rift history is just as important as mantle temperature in controlling the level of volcanic activity on the Earth’s surface.’
August 2010
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