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Science

New Insights into Ocean Floor Volcanic Activity

New research has shown that massive volcanic eruptions are not always commonplace when the Earth’s crust breaks apart.

[social_buttons]Published in the journal Nature, the study reveals that when continental plates break apart there is not always a corresponding volcanic eruption on the ocean floor. This discovery helps explain why some parts of our planet have seen massive volcanic eruptions and others have not.

“Mass extinctions, the formation of new continents and global climate change are some of the effects that can happen when plates break apart and cause super volcanic eruptions,” says Dr Jenny Collier, co-author from the Department of Earth Science and Engineering at Imperial College London. “Excitingly, our study is helping us to see more clearly some of the factors that cause the events that have helped to shape the Earth over millions of years.”

The earth’s crust is made up of massive plates that are constantly in movement, moving away from and crashing into one another. Sometimes they fuse together and create massive mountain rifts and others they break apart. When what is known as North America broke apart from Europe some 54 million years ago there was a mass of volcanic activity along the rift between the two. Many scientists thought that whenever these plates ripped apart there was a corresponding eruption of hot magma.

But when present day India broke away from what is now the Seychelles – an island country of 115 islands in the Indian Ocean – there was minimal volcanic activity.

“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,” added Dr John Armitage, lead author of the paper from the Department of Earth Science and Engineering at 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.”

In the case of the North American separation the huge amount of volcanic activity occurred because the plate was extremely thin, creating a focal point where the plate would easily melt allowing magma to erupt easily through the thinned plate.

However when India broke away from the Seychelles there had already been a significant volcanic activity experienced in the Gop Rift 6 million years earlier – a relative short period in geological terms – which meant there was a highly reduced supply of magma left to erupt when the rift occurred.

The team hope to take their methods to the ocean floor off the coast of South America where it split from Africa so long ago to determine the level of volcanic activity that took place.

Source: Imperial College London

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