Printable Version of Topic

Posted by: RGClark Oct 22 2005, 06:30 AM

New Map Provides More Evidence Mars Once Like Earth.
http://www.physorg.com/news7323.html

See for example here:

Plate Tectonics: The Mechanism.
http://www.ucmp.berkeley.edu/geology/tecmech.html

Bob Clark

Posted by: Richard Trigaux Oct 22 2005, 07:27 AM

Interesting...

but the banded patterns appear only in half of Mars, and are really apparent in only one region.

Either there was only a start of plate tectonics, or the magnetic remnants were later cancelled.

With my opinion this plate tectonics existed only in early Mars history, the first hundred million years. It resulted into a relatively flat surface, without continents (on Earth continents appeared only a billion years after the beginning). (All the surface features of this epoch are now hidden by the intense cratering of early solar system). But when the marsian core solidified, the magnetif field disappeared, the plate tectonics ceased, and since the marsian tectonics is very different of Earth's, resulting into the Tharsis dome and located but very large volcanoes.

Recent measurements of Earth heat source suggest that the solidifying of the core yelds four times more heat than radioactive heating. This results in mantle movements driven by the very bottom. On Mars there is only radioactive heating diffuse into the mantle, explaining that its today tectonics may be very different of Earth's.

Posted by: dvandorn Oct 22 2005, 08:02 AM

I think we need heat flow measurements from several thousands locations on Mars, and seismometers in several hundred locations, before we can even start to theorize about the current state of Mars' mantle and core...

-the other Doug

Posted by: Richard Trigaux Oct 22 2005, 11:23 AM

The only hints we have is what we can see on the surface:

-Tharsis dome
-Volcanoes
-fault zones around the Tharsis dome
-Vales Marineris
-two different origins for lavas

This gives some suggestion, for instance that it does not look like a Earth like convection scheme. But is not enough to give an overal shema of martian interior. What we need, I think, would be an extensive network of seismometres to have a map of inner Mars. And a coarse map is very likely to show only an homogenous mantle. The interesting features are likely to be small (lava chambers and chimneys) and scarcely "visible" (very weak differences in propagation speed, like hot spots on Earth).

Many seismometres would be expensive; but eventually we could do with less seismometres and many impacts which are cheaper to provide.

Posted by: SigurRosFan Oct 22 2005, 03:21 PM

http://www.unmannedspaceflight.com/index.php?showtopic=1549