What drives the motion of the plates on the earth?,geophysical and geochemical evidence for mantle convection?

Question

What drives the motion of the plates on the earth?,geophysical and geochemical evidence exists for mantle convection? Is the whole mantle convecting or just part of it?

Answer 1

Plate motion is mainly driven by density, which causes subduction and mid-ocean ridges (sea floor speading).

A mid ocean ridge is an area where new sea floor is created throught the divergent (speading) motion of the tectonmic plates in that area. It comes down to density. The center of the ridge is high, because it it new (just formed) and hot. The edges are low because it is old and cold. There are two main theories on the cause: slab pull and ridge push.

Ridge push is the classic idea that the ridge is a high point of a convection current, pushing the plates aside and allowing new mantle material to rise up and fill the hole.

Slab pull is the new idea that the subducting end of the plate, that is really old and dense, pulls on the entire plate as it subducts, and thus pulls apart itself in places, causing a hole which is then filled by rising material, forming the ridge.

It's kinda a chicken/egg thing, so we may never be able to rule one or the other out.

Geochemical evidence (isotopes showing mantle source in MORBs) and geophysical evidence (deepest earthquakes at subduction zones) supports the fact that this occurs, but does not specifically address the cause.

Answer 2

The main driving force for mantle convection is thought to be the heat released from thermonuclear decay of radioactive elements. The main elements responsible are thought to being uranium, thorium and potassium. Although potassium releases little energy when compaired to uranium and thorium, the large amount of potasium compaired to the trace amounts of uranium and thorium means the little atom can compete with its bigger brothers in creating convection. At present there are two theories of mantle convection: whole mantle convection and two half mantle convection. Since no-one has been to the mantle, geochemical evidence is hard to come by. Also, since the mantle convects slowly, geophysical evidence is hard to come by. Some xenoliths and some stony meteorites provide a little geochemical evidence, but that is all.

Answer 3

attempt to image a volcano that's point with floor, ....... now it in simple terms shall we out a sluggish continual flow. now image that volcano in simple terms below the branch of two separate plates.as this "volcano" is spewing the lava and shifting the plate so slowly like1/eighth of an inch a 300 and sixty 5 days an that's it however the information it there is in any different case charged volcanic rock and +=valuable -=detrimental and v=the area of the volcano the place the lava comes out. ++--++--++--++V++--++--++-- see notic how the trend is the comparable? nicely that's the way it quite is Im surprisingly optimistic that's the way it quite works

Answer 4

true, all those plate tectonics stuff r true, but what they are saying now is what moves them? they say its the energy from the mantle, and im pretty sure too, since that guy says the magma from the mantle rises n everything causing colition of plates right? so the scientists r saying now its the heat energy from the mantle

Answer 5

Isn't it the liquid rock mantle below the crust? And the liquid iron etc below that?

Answer 6

Gee, J, I think the geophysical convects it, doesn't it?