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.What drives the motion of the plates on the earth?,geophysical and geochemical evidence for mantle convection?
Isn't it the liquid rock mantle below the crust? And the liquid iron etc below that?What drives the motion of the plates on the earth?,geophysical and geochemical evidence for mantle convection?Gee, J, I think the geophysical convects it, doesn't it?What drives the motion of the plates on the earth?,geophysical and geochemical evidence for mantle convection?
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 mantleWhat drives the motion of the plates on the earth?,geophysical and geochemical evidence for mantle convection?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.
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