What occurs at oceanic ridges?
Mid-ocean ridges occur along divergent plate boundaries, where new ocean floor is created as the Earth’s tectonic plates spread apart. As the plates separate, molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt.
What happens when oceanic plates spread?
Mid-ocean ridges and seafloor spreading can also influence sea levels. As oceanic crust moves away from the shallow mid-ocean ridges, it cools and sinks as it becomes more dense. This increases the volume of the ocean basin and decreases the sea level.
What happens to new oceanic crust at a mid-ocean ridge?
Oceanic crust is continuously being created at mid-ocean ridges. As plates diverge at these ridges, magma rises into the upper mantle and crust. As it moves away from the ridge, the lithosphere becomes cooler and denser, and sediment gradually builds on top of it.
Do eruptions occur at mid-ocean ridges?
At mid-ocean ridges, eruptions are generally dominated by the gentle effusion of basaltic lavas with a low volatile content. However explosive volcanism has been documented at some ocean spreading centres, indicative of abundant volatile compounds.
What two processes happen at mid-ocean ridges?
There are two processes, ridge-push and slab-pull, thought to be responsible for the spreading seen at mid-ocean ridges, and there is some uncertainty as to which is dominant. Ridge-push occurs when the weight of the ridge pushes the rest of the tectonic plate away from the ridge, often towards a subduction zone.
What types of rocks do you find at mid-ocean ridges?
Igneous rock is formed by the cooling and crystallization of molten magma at volcanoes and mid-ocean ridges, where new crust is generated. Examples of igneous rock are basalt, granite, and andesite (Fig.
How far below the surface are mid ocean ridges?
What are the characteristics of mid ocean ridges?
Principal characteristics. Oceanic ridges are found in every ocean basin and appear to girdle Earth. The ridges rise from depths near 5 km (3 miles) to an essentially uniform depth of about 2.6 km (1.6 miles) and are roughly symmetrical in cross section. They can be thousands of kilometres wide.
What does the presence of new rock near an oceanic ridge indicate?
There is always a deep-sea trench underneath. There is evidence of seafloor spreading. They are made from oceanic crust.
Why is seafloor spreading important?
Significance. Seafloor spreading helps explain continental drift in the theory of plate tectonics. When oceanic plates diverge, tensional stress causes fractures to occur in the lithosphere. At a spreading center, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed.
What is the average speed of seafloor spreading?
approximately 5 centimeters a year
Which boundaries is seafloor destroyed?
You are correct that the seafloor is destroyed at subduction zones, but it is simultaneously being created at mid-ocean ridges. see figure 1 . Figure 1: Seafloor spreading at a mid-ocean ridge(where new crust is being created) and it’s destruction at a subduction zone.
How do you calculate seafloor spreading?
It is possible to calculate the spreading rate of one side of a mid-ocean ridge by dividing distance by time (Distance/Time = Rate).
Where is the youngest oceanic crust found?
The youngest crust of the ocean floor can be found near the seafloor spreading centers or mid-ocean ridges. As the plates split apart, magma rises from below the Earth’s surface to fill in the empty void.
Where does new oceanic crust from?
New oceanic crust is continuously being formed as magma upwells at mid-ocean ridges. The characteristics of oceanic crust hold clues about its age and the environment in which it formed.
What is the approximate age of the oldest oceanic crust?
about 260 million years