Re: OIL PRICES ABOUT TO CRASH; DRUDGE REPORT


Alan Bowler wrote:
> Ron Peterson wrote:

> > If the earth's core was as radioactive as its surface, the earth would
> > be molten.

> Actually the CORE should be expected to be MORE radioactive than the
> surface. Uranium and thorium are heavier than almost everything
> else and tend to sink to the core. There is just not as much of them
> as the iron and nickel that also sank to make up the bulk of the core.

> It is the heat from the gradual decay of the radioactive
> elements (principally uranium and thorium) that keeps the
> core molten.

Newscientist.com has the following article:
First measurements of Earth's core radioactivity
27 July 2005
NewScientist.com news service
Celeste Biever

EARTH'S natural radioactivity has been measured for the first time. The
measurement will help geologists find out to what extent nuclear decay
is responsible for the immense quantity of heat generated by Earth.

Our planet's heat output drives the convection currents that churn
liquid iron in the outer core, giving rise to Earth's magnetic field.
Just where this heat comes from is a big question. Measurements of the
temperature gradients across rocks in mines and boreholes have led
geologists to estimate that the planet is internally generating between
30 and 44 terawatts of heat.

Some of this heat comes from the decay of radioactive elements. Based
on studies of primitive meteorites known as carbonaceous chondrites,
geologists have estimated Earth's uranium and thorium content and
calculated that about 19 terawatts can be attributed to radioactivity.
But until now there has been nothing definitive about exactly how much
uranium there is in the planet, says geologist Bill McDonough of the
University of Maryland in College Park. "There are fundamental
uncertainties."

There is one way to lessen this uncertainty, and that is to look for
antineutrinos. These particles are the antimatter equivalent of the
uncharged, almost massless particles called neutrinos and are released
when uranium and thorium decay to form lead. If antineutrinos are being
created deep within the planet they should be detectable, because they
can pass through almost all matter.

Now, the KamLAND antineutrino detector in Kamioka, Japan, has counted
such antineutrinos. An international team of scientists analysed the
data and found about 16.2 million antineutrinos per square centimetre
per second streaming out from Earth's core. They calculate that the
nuclear reactions creating these particles could be generating as much
as 60 terawatts, but are most likely putting out about 24 terawatts
(Nature, vol 436, p 499). "We have made the first measurements of the
radioactivity of the whole of Earth," says John Learned, who heads the
KamLAND group at the University of Hawaii in Manoa. The KamLAND group's
finding is like unwrapping a birthday present, says McDonough.

With time, as more antineutrinos are detected, KamLAND may be able to
determine once and for all whether radioactivity is entirely
responsible for heating Earth or whether other sources, such as the
crystallisation of liquid iron and nickel in the outer core, also play
a significant role. "[Detecting anti-neutrinos] is the way of the
future in terms of hard numbers about the system," says McDonough.

Antineutrinos could also reveal the radioactive composition of the
crust and mantle, which will give geologists clues as to when and how
they formed. But to do that, they will have to be able to pin down
exactly where the antineutrinos are coming from, and this will require
a whole network of detectors. "We are heading towards doing neutrino
tomography of the whole Earth," says Learned. "This is just the first
step."

>>From issue 2510 of New Scientist magazine, 27 July 2005, page 9

--
Ron

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Relevant Pages

  • Re: molten cores
    ... It is rare to find it in economically minable Uranium ores but bulk abundance is 2ppm in the crust (and likely slightly higher in the core). ... Although magma doesn't consist of core material at all, ... So, if magma did come from the core, it would have very little radioactivity anyway. ...
    (sci.astro.amateur)
  • Re: molten cores
    ... radioactivity show up in magma reaching the surface? ... The primary radioisotopes associated with internal heating are U-238 ... Earth's core. ...
    (sci.astro.amateur)
  • Re: molten cores
    ... core, mantle, and crust is about 6e-12 watts/kg. ... Although magma doesn't consist of core material at all, ... magma did come from the core, it would have very little radioactivity ...
    (sci.astro.amateur)
  • Re: molten cores
    ... radioactivity show up in magma reaching the surface? ... The primary radioisotopes associated with internal heating are U-238 ... Earth's core. ...
    (sci.astro.amateur)