How are plate tectonics and seafloor spreading related? | Socratic
They named the process sea-floor spreading. Moreover, they proposed that the topographic contrast between the ridges and the oceanic abyssal plains was as. Revival of Continental Drift Theory. • Kiyoo Wadati () speculated that earthquakes and volcanoes may be associated with continental drift. • Hugo Benioff. The land masses (not only the continents) portray many examples of about the tectonic plates and the apparent spreading of the ocean floors, the thesis about or not do in relation to that particular matter-energy event; i.e. Earth in this case.
Looks at the relationship between plate tectonics and marine mineral deposits; shows how the ocean floor is being mapped and looks at recovery systems for marine resources including underwater scoops and shovels and giant "vacuum cleaners". Box ; Princeton, N. Describes methods of exploring the oceans; interaction of oceans with the biosphere, lithosphere, and atmosphere to create a unique environment; and the three main characteristics of oceans: Order from Scott Resources, P.
Collins, CO, ; phone This set illustrates submarine research using deep water submersibles and remotely operated vehicles to study ocean floor rift systems.
Includes photos of black smokers, tube worms, and equipment used by oceanographers. Order from the American Geophysical Union, Attn.: Orders, Florida Avenue, N. In this module students examine data from sediments on the ocean floor, determine whether the data support the theory of sea-floor spreading, and calculate the rate of spreading of the East Pacific Rise. Other CEEP modules related to the ocean floor include: BoxRochester, New York ; phone But before we try to perform the following exercise, I will present a very brief overview of plate tectonics and sea floor spreading.
I encourage you to consult the web links indicated, if you feel you need more than this refresher. As mantle material partially melts and solidifies again there seem to be an enrichment of specific elements light ones in the newly formed crustal material and retention of remaining elements heavier ones in the originating mantle material.
How are plate tectonics and seafloor spreading related?
This process may not only end with the formation of oceanic crust but may also be responsible for the formation of continental crust as well. Driving mechanism for plate motion.
Convection in the astenosphere brings new material up into the "cracks" of the mid-oceanic ridge and at the same time drags plates away from the center point of separation. However, less common but still important outpouring of lava occurs in the interior of plates, thousands of kilometers away from the plate edges.
Tuzo Wilson, a Canadian geophysicist, came up with an ingenious idea that became known as the "hotspot" theory. Wilson noted that in certain locations around the world, such as Hawaii, volcanism has been active for very long periods of time. This could only happen, he reasoned, if crustal plates were to drift slowly over deep-seated relatively small, long-lasting, and exceptionally hot regions - called hotspots or mantle plumes.
Mantles plumes are placed where molten rock originates deep below the astenosphere. As this molten rock rises it melts its way through the lithosphere, spilling out as lava on the top of the plate.
With time million of years large quantities of lava are added to the pile, creating a volcanic cone that towers above the ocean floor and eventually above sea level forming thus an island. Ultimately, the motion of the plate, as a result of sea-floor spreading, transports the newly formed island beyond the mantle plume cutting off its supply of lava.
At this stage the island stops growing and erosion begins to wear down its rocks. As one island volcano becomes extinct, another develops over the hotspot, and the cycle is repeated see Figure 2 below.
The growth of volcanic islands by mantle-plume injection hot-spot activity thus results in the formation of linear chains of islands such as the one observed in the Hawaiian Islands Figure 2.
The volcanoes of the Hawaiian chain get progressively older and become more eroded the farther they travel beyond the hotspot. This environment is a chain of small islands that are produced from a hot-spot center deep below the ridge in the middle of the South Atlantic Ocean.
The latest of these islands is called Ascension see Figure 3 below and as it "sits" presently right in the Middle of the South Atlantic Ocean and it also tells us something quite amazing about how life forms can adapt to perform astounding exploits. It is the story of sea turtles and million years of their evolution.
Millions of years ago the shapes of the continent s were not what they are today and landmasses and oceans basins were organized in a different fashion. Please consult the following web site to see the evolution and distribution of landmasses in the last million years: Click on animation to have a dynamic vision of the change that occurred during that time. When oceanic plates divergetensional stress causes fractures to occur in the lithosphere. The motivating force for seafloor spreading ridges is tectonic plate pull rather than magma pressure, although there is typically significant magma activity at spreading ridges.
Hydrothermal vents are common at spreading centers. Older rocks will be found farther away from the spreading zone while younger rocks will be found nearer to the spreading zone. Additionally spreading rates determine if the ridge is a fast, intermediate, or slow.
Spreading centers end in transform faults or in overlapping spreading center offsets. A spreading center includes a seismically active plate boundary zone a few kilometers to tens of kilometers wide, a crustal accretion zone within the boundary zone where the ocean crust is youngest, and an instantaneous plate boundary - a line within the crustal accretion zone demarcating the two separating plates.
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Unsourced material may be challenged and removed. April Learn how and when to remove this template message Plates in the crust of the earth, according to the plate tectonics theory In the general case, sea floor spreading starts as a rift in a continental land masssimilar to the Red Sea- East Africa Rift System today. Because less dense objects rise in relation to denser objects, the area being heated becomes a broad dome see isostasy. As the crust bows upward, fractures occur that gradually grow into rifts.
The typical rift system consists of three rift arms at approximately degree angles. These areas are named triple junctions and can be found in several places across the world today. The separated margins of the continents evolve to form passive margins.
Hess' theory was that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge. If spreading continues past the incipient stage described above, two of the rift arms will open while the third arm stops opening and becomes a 'failed rift'.