Oceans

Seafloor Spreading

The floors of sea are not one contiguous basin. It just like the world that you see, with valleys, plateaus and mountains, except that it is all covered with water. Moreover, there are areas in the sea floor that are more 'active' than the rest. These areas are prone to faulting, fracturing, volcanic activity and spreading. Sea floor spreading is a basic premise that helps postulate the theory of plate-tectonics. The first stage in plate separation is the initiation of a new pattern of convection within the Earth’s mantle, which brings hot mantle material to high levels inside the Earth (fig 1). The elevated temperature and buoyant effect of the rising plume arches up the oceanic crust, causing it to extend. As the plates continue to diverge, further fracturing of the thinned oceanic crust occurs. The new oceanic crust cools and moves away on either side of the spreading axis. As it cools, it becomes denser and subsides, gradually generating the low lying ocean floor, which becomes imprinted with magnetic anomalies as polarity reversals take place. The seafloor lava acquire a veneer of marine sedimentary rocks, produced by marine organisms. The margins of the ocean are marked by normally faulted continental edges, partly due to subsidence of the oceanic crust. Continental shelves develop along the continental edges and receive sediments worn by erosion of the adjacent continental...

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