What is mid-ocean ridge basalt?
Mid-ocean ridge basalt (commonly referred to as MORB) is a variety of submarine basalt erupted, in response to sea floor spreading, along the entire length of the Earth’s mid-ocean ridge system (some 65 000 km in length).
Does basalt form at mid-ocean ridges?
Most of the world’s basalt erupts quietly in the deep sea, along the mid-ocean ridges—the spreading zones of plate tectonics. Lesser amounts erupt on volcanic ocean islands, above subduction zones, and in occasional large outbursts elsewhere.
How do mid-ocean ridges make new basalt?
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 rock is formed at mid-ocean ridges?
The material that erupts at spreading centers along the mid-ocean ridge is primarily basalt, the most common rock on Earth. Because this spreading occurs on a sphere, the rate separation along the mid-ocean ridge varies around the globe.
What type of basalt that forms mounds at mid-ocean ridges?
Mid-Ocean Ridge Magmatism: By far, the dominant type of lava resulting from magmatic activity at mid-ocean ridges is basalt, also called mid-ocean ridge basalt (MORB).
What observation has been made about the age of the basalt that forms a mid-ocean ridge?
What observation has been made about the age of basalt that forms mid ocean ridge? Basalt an ignasious rock formed at mid ocean ridges is younger than all other rock away from it.
What type of rock is a basalt?
Basalt. Basalt is a hard, black volcanic rock. Basalt is the most common rock type in the Earth’s crust. Depending on how it is erupted, basalt can be hard and massive (Figure 1) or crumbly and full of bubbles (Figure 2).
What is basalt made of?
Basalts are composed of minute grains of plagioclase feldspar (generally labradorite), pyroxene, olivine, biotite, hornblende, and less than 20% quartz. The mineral nepheline or leucite may associate or proxy the feldspar giving rise to verities with special names.
What is the importance of basalt?
Basalt is used for a wide variety of purposes. It is most commonly crushed for use as an aggregate in construction projects. Crushed basalt is used for road base, concrete aggregate, asphalt pavement aggregate, railroad ballast, filter stone in drain fields, and may other purposes.
How is it formed of basalt?
Basalts are formed by rapid cooling of basaltic lava, equivalent to gabbro–norite magma, from the interior of the crust and exposed at or very close to the surface. These basalt flows are thick and extensive in which gas cavities are nearly absent.
What are mid-ocean ridge basalts (MORB)?
Experimental results indicate that mid – ocean ridge basalts (MORB) are produced by 10-20% partial melting of the upper mantle at depths of 50-85 km ( Elthon & Scarfe, 1984; Kushiro, 2001 ). Ocean ridge basalts depleted in the most incompatible elements (e.g., Rb, Ba, U, and K) are known as NMORB (normal ocean ridge basalts).
What are normal ocean ridge basalts?
Ocean ridge basalts depleted in the most incompatible elements (e.g., Rb, Ba, U, and K) are known as NMORB (normal ocean ridge basalts). Melting at these depths produces olivine tholeiite magma.
Why are mid-ocean ridges geologically important?
Mid-ocean ridges are geologically important because they occur along divergent plate boundaries, where new ocean floor is created as the Earth’s tectonic plates spread apart. As the plates separate, some molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt, and building the longest chain…
What is the average depth of a mid oceanic ridge?
The majority of the system is underwater, with an average water depth to the top of the ridge of 2,500 meters (8,200 feet). Mid-ocean ridges occur along divergent plate boundaries, where new ocean floor is created as the Earth’s tectonic plates spread apart.