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January 11, 2008
Earth's Geology May be What Keeps Water Wet
Hansen recently stirred the pot with a controversial hypothesis published in last month's issue of the journal Geology. Meteorite impacts early in Earth's history, she suggested, created the first rifts in the crust, jump-starting plate tectonics.[...]
Energizer Bunny Tectonics?
"It's an implicit assumption that plate tectonics never shuts down," Silver told Discovery News. "But it's nowhere stated in plate tectonics theory."Silver and his colleague Mark Behn proposed in the Jan. 4 issue of Science that all it takes to stop plate tectonics is the devouring of the crustal plate under the Pacific Ocean. And that's not as far-fetched as it sounds.
[...]
The end result would be a supercontinent, no remaining subduction zones, and virtually no plate tectonics, at least for a while.
(via disovery news)
"If Mars were to have plate tectonics, it would have to be bigger early on," said Valencia. This is because plate tectonics require a planet to have a lot of interior heat to keep things moving. Smaller planets dissipate their heat faster, and so have a very short window of time for plate tectonics.Venus, on the other hand, is about the same size as Earth, but it lacks water, said Hansen. Without water in the mantle to help melt rocks and trigger volcanic recycling of material, Venus' crust appears to have remained stiff and locked up forever. Had Venus held more water, or if it had been a super-sized rocky planet, it too would have had plate tectonics and perhaps life.
Posted by Groonk at January 11, 2008 07:51 PM | Ministry of Mars, Research, Science
