Two-Billion-Year-Old Surprise Found Beneath The Azores

http://www.spacedaily.com/news/early-earth-02h.html

Geologists may have to revise their ideas about what goes on in the Earth's
interior, following the publication today of new research in the journal
Nature.
It appears that contrary to previous belief, part of the interior has
remained undisturbed for at least two-and-a-half billion years, in spite of
the massive forces at work inside the planet.

Like a saucepan of thick syrup being heated on the stove, huge convection
currents within the Earth, generated by heat from the core, have stirred up
the interior for most of its four-and-a-half billion year history. This has
led geologists to believe that the interior is now well mixed.

But Dr Simon Turner and Professor Chris Hawkesworth from the Earth Science
Department at Bristol University, with colleagues at the Open University,
have new data that suggest the presence of extremely ancient material
beneath the Azores.

The islands of the Azores are volcanoes that sit either side of the
Mid-Atlantic Ridge, a huge mountain chain beneath the ocean that formed as
hot material from the Earth's interior rose to the surface. In some places,
such as the Azores, the tops of these mountains form islands.

The lavas from the Azores volcanoes appear to have been derived from some
of the oldest material yet discovered within the convecting and well
stirred part of the Earth.

One of the few ways to obtain information about the processes that go on in
the Earth's interior is to analyse material that is brought up from these
depths. The researchers therefore analysed the ratios of certain elements
in the lavas that specifically characterise the source material they were
derived from.

Dr Turner said: "The osmium ratios obtained in some of the Azores rocks are
among the lowest ever seen in oceanic lavas. This indicates that the region
from which the lavas were derived contained material that was left behind
when continents were formed about two-and-a-half billion years ago.

"This depleted material was subsequently recycled back into the interior
beneath the volcanic islands, where it has remained ever since."

The fact that such old material could reside in the Earth's interior for so
long without being recycled will help inform new models about processes
that go on inside the Earth.


.

Relevant Pages

  • Re: Two-Billion-Year-Old Surprise Found Beneath The Azores
    ... > interior, following the publication today of new research in the journal ... > But Dr Simon Turner and Professor Chris Hawkesworth from the Earth Science ... > beneath the Azores. ... > The lavas from the Azores volcanoes appear to have been derived from some ...
    (sci.geo.geology)
  • Re: The Epic of Gilgamesh
    ... and various things which seem to pass through time in dreams provided ... did not happen on earth. ... terraformed moon. ... in the interior crew quarters of the ship. ...
    (talk.origins)
  • Re: What is this convection cell nonsense
    ... into the interior at the subduction zone. ... The inference of differential rotation in the molten/flexible interior ... still attribute a pseudo-dynamic of variable axial tilt to the Earth ...
    (sci.geo.geology)
  • Re: error in mathematics behind black holes
    ... the typical analogy with polar coordinates on Earth, ... *study* the interior using Kruskal coordinates. ... but an observer in freefall will drop from Region ... where a is the proper acceleration). ...
    (sci.physics.relativity)
  • Re: The Epic of Gilgamesh
    ... and various things which seem to pass through time in dreams provided ... home, and some of those things, on earth. ... terraformed moon. ... in the interior crew quarters of the ship. ...
    (talk.origins)