Ancient Supervolcano Created Giant Underwater Mountain Chain

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By Charles Q. Choi, LiveScience Contributor
posted: 09 April 2010 03:16 pm ET


A supervolcano on the ocean floor might have spewed massive amounts of lava in a rapid amount of time, new findings that could help reveal the mysterious origin of some of these ancient goliaths, which may have triggered mass extinctions through Earth's history.

Roughly a dozen supervolcanoes currently exist. Some are on land, while others lie at the bottom of the ocean. Each has produced several million cubic miles of lava — about three hundred times the volume of all the Great Lakes combined — dwarfing the amount of lava produced by the Hawaiian volcanoes or the Icelandic volcano that erupted recently.

These eruptions have dramatically shaped life on Earth, pumping huge amounts of ash, dust and gas into the atmosphere that have killed off species and altered global climate. Despite their global impact, the cause of the massive eruptions from supervolcanoes at times remains unknown.

The mystery lies in the origin of their magma, or molten rock within the Earth. Magma rising from deep within the Earth has a different isotopic and chemical composition than magma that forms just below Earth's crust. Some ocean supervolcanoes, known as large oceanic plateaus, show signs of a deep-mantle origin, while others possess chemical signatures of magma from a much shallower depth.

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http://www.livescience.com/environment/Supervolcano-Underwater-Mountain-Chain-100409.html