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mid ocean ridge: a long, seismically active submarine ridge system situated in the middle of an ocean basin and marking the site of the upwelling of magma associated with seafloor spreading. An example is the Mid-Atlantic Ridge.
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Convergent Boundary:_A subduction zone is formed at a convergent plate boundary
when one or both of the tectonic plates is composed of oceanic crust.
The denser plate, made of oceanic crust, is subducted underneath the
less dense plate, which can be either continental or oceanic crust.