Thursday, February 16, 2012

Lava formations in western US linked to rip in giant slab of Earth

Like a stream of air shooting out of an airplane's broken window to relieve cabin pressure, scientists at Scripps Institution of Oceanography at UC San Diego say lava formations in eastern Oregon are the result of an outpouring of magma forced out of a breach in a massive slab of Earth.

Their new mechanism explaining how such a large volume of magma was generated is published in the Feb. 16 issue of the journal Nature. For years scientists who study the processes underlying the planet's shifting tectonic plates and how they shape the planet have debated the origins of sudden, massive eruptions of lava at the planet's surface.

In several locations around the world, such "flood basalts" are marked by immense formations of volcanic rock. A famous example is India's Deccan flood basalt, a formation widely viewed as related to the demise of the dinosaurs 65 million years ago.

Such eruptions are thought to typically occur when the head of a mantle plume, a mushroom-shaped upwelling of hot rock rising from deep within Earth's interior, reaches the surface.

Now Scripps postdoctoral researcher Lijun Liu and geophysics professor Dave Stegman have proposed an alternative origin for the volcanic activity of Oregon's Columbia River flood basalt. Read More