PDA

View Full Version : Geophysicists challenge traditional theory underlying the origin of mid-plate volcano



Swift
2014-Dec-05, 03:26 PM
From R&D magazine (http://www.rdmag.com/news/2014/12/geophysicists-challenge-traditional-theory-underlying-origin-mid-plate-volcanoes?et_cid=4302124&et_rid=54636800&type=cta)


A long-held assumption about the Earth is discussed in Science, as Don L. Anderson, an emeritus professor with the Seismological Laboratory of the California Institute of Technology, and Scott King, a professor of geophysics in the College of Science at Virginia Tech, look at how a layer beneath the Earth's crust may be responsible for volcanic eruptions.

The discovery challenges conventional thought that volcanoes are caused when plates that make up the planet's crust shift and release heat.

Instead of coming from deep within the interior of the planet, the responsibility is closer to the surface, about 80 km to 200 km deep—a layer above the Earth's mantle, known as the as the asthenosphere.

"For nearly 40 years there has been a debate over a theory that volcanic island chains, such as Hawaii, have been formed by the interaction between plates at the surface and plumes of hot material that rise from the core-mantle boundary nearly 1,800 miles below the Earth's surface," King said. "Our paper shows that a hot layer beneath the plates may explain the origin of mid-plate volcanoes without resorting to deep conduits from halfway to the center of the Earth."



Here is the link to the Science abstract (http://www.sciencemag.org/content/346/6214/1184.short)


The asthenosphere—derived from the Greek asthenēs, meaning weak—is the uppermost part of Earth's mantle, right below the tectonic plates that make up the solid lithosphere. First proposed by Barrell 100 years ago (1), the asthenosphere has traditionally been viewed as a passive region that decouples the moving tectonic plates from the mantle and provides magmas to the global spreading ridge system. Recent studies suggest that the asthenosphere may play a more active role as the source of the heat and magma responsible for intraplate volcanoes. Furthermore, it may have a major impact on plate tectonics and the pattern of mantle flow.


The full article is behind a pay-wall.

grapes
2014-Dec-05, 03:32 PM
It mentions the debate that has gone on for forty years. Don Anderson has been central to that debate, and probably this is just an addition to that debate, not a resolution of the debate.