Theory and Evidence of Seafloor Spreading | Earth Eclipse
Mid-ocean ridges are part of chain of mountains some 84, km long. . Looks at the relationship between plate tectonics and marine mineral Includes photos of black smokers, tube worms, and equipment used by oceanographers. The mid-ocean ridge is the place where new oceanic crust is being created by the intrusion and extrusion of basaltic magma, which rises up. An explanation of relevant tectonic forces · Mid-Oceanic ridge, Ridge, Studying Mid-Ocean Ridges from Mantle to Microbe.
Seafloor spreading was proposed by an American geophysicist, Harry H. By the use of the sonar, Hess was able to map the ocean floor and discovered the mid-Atlantic ridge mid-ocean ridge.
Sedimentation on mid-ocean ridges
He also found out that the temperature near to the mid-Atlantic ridge was warmer than the surface away from it. He believed that the high temperature was due to the magma that leaked out from the ridge. The Process of Sea Floor Spreading The mid-ocean ridge is the region where new oceanic crust is created. The oceanic crust is composed of rocks that move away from the ridge as new crust is being formed.
- Mid-ocean ridge
- What is the relationship between the mid-ocean ridge and sea floor spreading?
- The Theory of Seafloor Spreading
The formation of the new crust is due to the rising of the molten material magma from the mantle by convection current.
When the molten magma reaches the oceanic crust, it cools and pushes away the existing rocks from the ridge equally in both directions. A younger oceanic crust is then formed, causing the spread of the ocean floor. The new rock is dense but not as dense as the old rock that moves away from the ridge. As the rock moves, further, it becomes colder and denser until it reaches an ocean trench or continues spreading.
It is believed that the successive movement of the rocks from the ridge progressively increases the ocean depth and have greater depths in the ocean trenches.
Seafloor spreading leads to the renewal of the ocean floor in every million years, a period of time for building a mid-ocean ridge, moving away across the ocean and subduction into a trench. The Subduction Process The highly dense oceanic crust that is formed after a progressive spreading is destined to two possible occurrences.
It can either be subducted into the ocean deep trench or continue to spread across the ocean until it reaches a coast. Subduction is the slanting and downward movement of the edge of a crustal plate into the mantle beneath another plate.
what is the relationship between the mid-ocean ridge and sea floor spreading? | Yahoo Answers
It occurs when an incredibly dense ocean crust meets a deep ocean trench. On the other hand, if the ocean crusts continuous to move along the ocean and not found a trench, no subduction will occur. It will continue to spread until a coast is found and literally pushing it away towards its direction. Two possible things could happen in the subduction of ocean crust. Once the subduction occurs, a melting happens due to a tremendous friction. The ocean crust is then melted into magma.
The magma could either go back into the mantle for another convection currents leading again to another sea floor spreading or it could burst through a crack in a continental crust and creates a volcano.
Subduction and sea-floor spreading are processes that could alter the size and form of the ocean.
For instance, the Atlantic Ocean is believed to be expanding because of its few trenches. Due to this, continuous Seafloor spreading occurs and makes Atlantic Ocean floor to be connected to other continental crust making the ocean gets wider over the time.
The method essentially involved quantifying the amount of material eroded from or not deposited on the crests of fault scarps, and dividing this value by the age of the scarp which is well known from the seafloor spreading history.
Due to the method used, the result was an upper bound on rates of surficial sediment movement. Accumulation rates Sediment on ridge flanks commonly thicken with distance from the spreading axes, reflecting the increasing age of the volcanic seafloor.
Complications to this simple picture occur where there is substantial sediment transport or varied dissolution of carbonate. High resolution sediment profiler records collected on the Mid-Atlantic Ridge in CD99 show that this simple picture is not applicable there, which has implications for attempting to use the thickness of the sediment cover as a dating tool on slow-spreading ridges abstract.
However, sediments on the Galapagos spreading centre figure right do show a simple systematic trend, partly because the ridge lies beneath the equatorial zone of high pelagic productivity causing very high accumulation rates relative to rates of sediment redistribution and dissolution. Accumulation rates are higher on the south flank, closest to the centre of the high productivity zone.
Mapping lava flows Due to the high accumulation rates on the Galapagos spreading centre relative to sediment redistribution rates, the thickness of sediment is a useful proxy for seafloor age.
The ridge flanks have areas of near uniform sediment thickness which correspond to flat basement topography and are bounded by fault scarps. These areas are highlighted by horizontal bars in the figure left and were interpreted as regions of uniform age due to large lava flows. As a consequence of the flows, the surficial oceanic crust is slightly younger than might be predicted by simple seafloor spreading and distance of the seafloor from the ridge axis.