The first sort of plate boundary is called a divergent boundary , or spreading center. At these boundaries, two plates move away from one another.
What happens at a spreading center?
Spreading centers occur where two plates are moving away from each other, and deep cracks are opened through the crust . This lengthening of the crust allows magma from the upper mantle to rise to the surface and cool, commonly forming basalt. ... The crust is much thicker here, and so earthquakes are also stronger.
What is a spreading center?
Spreading centre, in oceanography and geology, the linear boundary between two diverging lithospheric plates on the ocean floor . ... Spreading centres are found at the crests of oceanic ridges.
How does a spreading center form?
Spreading center volcanism occurs at the site of mid-oceanic ridges, where two plates diverge from one another . As the plates are pulled apart, hot asthenosphere rises upward to fill voids of the extended lithosphere.
How deep are spreading centers?
At the spreading center on a mid-ocean ridge, the depth of the seafloor is approximately 2,600 meters (8,500 ft) . On the ridge flanks, the depth of the seafloor (or the height of a location on a mid-ocean ridge above a base-level) is correlated with its age (age of the lithosphere where depth is measured).
Why are magmas generated at spreading centers?
As the two plates separate, the mantle rock from the asthenosphere layer below flows up into the void between the plates. Because the pressure is not as great at this level, the mantle rock will melt, forming magma . ... This sort of magma production is called spreading center volcanism.
What is the fastest spreading center?
28°S–32°S East Pacific Rise . The fastest present-day seafloor spreading, ~150 km/Myr, occurs along the Pacific-Nazca boundary between the Easter and Juan Fernandez microplates. ...
Where are spreading centers found?
Spreading centres are found at the crests of oceanic ridges .
Why are the centers of spreading centers elevated?
Seafloor spreading occurs at divergent plate boundaries. As tectonic plates slowly move away from each other, heat from the mantle’s convection currents makes the crust more plastic and less dense. The less-dense material rises , often forming a mountain or elevated area of the seafloor.
What is it called when sea plates pull apart?
Divergent boundaries in the middle of the ocean contribute to seafloor spreading . As plates made of oceanic crust pull apart, a crack in the ocean floor appears. Magma then oozes up from the mantle to fill in the space between the plates, forming a raised ridge called a mid-ocean ridge.
What is an example of a spreading center?
The most famous spreading center is the Mid-Atlantic Ridge , but there are many others. California has a small spreading center located in the Brawley Seismic Zone of Imperial County, the northern-most spreading center of the East Pacific Rise.
Which is the first step in seafloor spreading process?
1. A long crack in the oceanic crust forms at a mid ocean ridge . 2. Molten material rises and erupts along the ridge.
What are the evidence of seafloor spreading?
The theory of seafloor spreading states that new ocean crust is continually being formed, and that this crust is slowly carried away from its point of origin over a period of time. The study of the repeated reversal of the Earth’s magnetic poles over time has provided convincing evidence of seafloor spreading.
How is heat flow provide evidence of spreading centers?
(c) How does heat flow provide evidence for rising convection currents at spreading centers? They form new oceanic crusts .
Who proved that the seafloor is spreading?
The seafloor spreading hypothesis was proposed by the American geophysicist Harry H. Hess in 1960.
Who discovered seafloor spreading?
Harry Hess : One of the Discoverers of Seafloor Spreading.
