DESTRUCTIVE PLATE MARGIN
Plates move towards eachother at desctructive margin, rock is destroyed. Oceanic crust pushes into continental curst there is a collision. Because the continental crust is less dense, the more dense oceanic crust forces its way underneath it. This is called SUBDUCTION and happens at a SUBDUCTION ZONE. As the oceanic crust is subducted down into the mantle is starts to melt. Also, it rubs against the continental crust, friction is created which also creates heat and causes the rock to melt.
CONSTRUCTIVE PLATE MARGIN