Tectonic Plate Recycling
Monday, 28. January 2008, 09:49:48
I had just started writing a new post concerning a paper that could change our view on mantle plumes, when I became aware of a weird piece in Der Spiegel. The post on which I began will now have to wait till tomorrow, but in some ways the two articles are related.
On January 25 2008 Spiegel Online International brought an article titled Where Continents Go To Die - A New Look into the Center of the Earth.
Let me start with saying that I don’t believe in this theory (yet), but find it worth discussing. So here we go.
Old, cold plates are pushed down into the Earth's mantle on the continental edges, where they collect large amounts of iron. Weighted down by the iron, the plates sink farther and farther into the Earth's mantle. There, at a depth of 2,900 km, they settle into "plate graveyards”. Heat and pressure in the depths trigger chemical processes, causing the plates to deposit their load of heavy elements. Once liberated of this burden (a few hundreds of millions years later), they become lighter than their surroundings, causing them to rise and as mantle plumes they make their way toward the surface (at hot spots etc.). Well, that is the biggest convection cell that I have ever heard of, and I must stress that this is only a (new) theory, that in no way has been proven by facts, as far as I know.
More about the mantle plume bit in my next post here.
• http://www.spiegel.de/international/world/0%2C1518%2C531023%2C00.html
• http://www.spiegel.de/international/world/0,1518,grossbild-1078154-531023,00.html
PS:
On January 25 2008 Spiegel Online International brought an article titled Where Continents Go To Die - A New Look into the Center of the Earth.
Let me start with saying that I don’t believe in this theory (yet), but find it worth discussing. So here we go.
Old, cold plates are pushed down into the Earth's mantle on the continental edges, where they collect large amounts of iron. Weighted down by the iron, the plates sink farther and farther into the Earth's mantle. There, at a depth of 2,900 km, they settle into "plate graveyards”. Heat and pressure in the depths trigger chemical processes, causing the plates to deposit their load of heavy elements. Once liberated of this burden (a few hundreds of millions years later), they become lighter than their surroundings, causing them to rise and as mantle plumes they make their way toward the surface (at hot spots etc.). Well, that is the biggest convection cell that I have ever heard of, and I must stress that this is only a (new) theory, that in no way has been proven by facts, as far as I know.More about the mantle plume bit in my next post here.
• http://www.spiegel.de/international/world/0%2C1518%2C531023%2C00.html
• http://www.spiegel.de/international/world/0,1518,grossbild-1078154-531023,00.html
PS:
- In another context (science journalists/journalism) Chris (goodSchist) had an indirect comment to this post over at Clastic Detritus (Response#2).
- There is a dedicated mantle plume website at http://www.mantleplumes.org/ with links to lots of (free) papers on mantle plumes.
WIDGETIZE