Mid Ocean Ridges

Q: 1. What is the Mantle?

Ans: Mantle lies between earth’s extremely heated dense core and crust (thin outer layer), which is a mostly solid mass. Mantle mass is around 84% of the earth's volume with a dimension of 2,900 kilometres (1,802 miles). During the formation of the earth, iron and nickel were segregated from other rocks and minerals to shape the core of the planet. The molten material that encases the core was the early mantle. Over millions of tears through the process of outgassing, the mantle cooled as trapped water erupted with lava. As more water was released, the mantle solidified. Major constituents of the mantle are silicates, a spectrum of compounds with oxygen and silicon structure.

Q: 2. What is Mantle convection?

Ans: Seal floor spreading and other tectonic activities are caused by mantle convection. It is a slow roiling process of the earth's mantle. From the lower mantle and core, the heat is carried to the lithosphere by convection current. Thermal convection in the mantles (the layer between crust and core) where hot substances rise, cold materials sink the resultant flow governs the tectonic and volcanic activities. This process cools the entire planet and segregates chemicals. All planetary bodies preserve some heat inside, but the surface cools inevitably. The earth's surface is relatively cooler than the interior; thus go through mantle convection, where hot materials rise and cold, dense materials sink.

Q: 3. What is the East Pacific Rise?

Ans: The East Pacific Rise is a typical example of a fast-spreading mid ocean ridge; this ridge has been comprehensively studied over four decades for its abundance of hydrothermal vents. At these vents, scientists are investigating the association between crustal accumulation, mantel flow, hydrothermal, volcanic, and biological processes that cause a physical and chemical change of matter and energy between the ocean floor and the earth's mantle. Specifically, a region named 9 North, nine hundred kilometres away from the coast of Acapulco, Mexico, where repeated seafloor volcanoes along the mid ocean ridge is observed.

Geography

Mid Ocean Ridges

Reviewed by:

Aiswarya Ittianath

What is a Mid-Ocean Ridge?

The mid ocean ridge is the most extensive range of underwater volcanic mountains encircling the earth, drawing out around nearly 65,000 kilometres (40,390miles). Most part (around 90%) of the mid ocean ridge is submerged under the deep sea. It is a focal feature of undersea geography, more stunning than land terrain, a beautiful assortment of volcanic ridges, rifts, fault zones, and other geological features. The mid ocean ridge occurs along divergent plate boundaries, a joint where Earth's tectonic plates diverge. As plates split apart, molten rocks fuzz in the seafloor, resulting in a mammoth eruption of basalt. The epicentre of most volcanoes of the earth occurs along the mid ocean ridge, and in this location, the earth's crust is bred.

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Fast and Slow-Spreading Mid Ocean Ridges

To know what a mid ocean is, ridge geologists well documented two mid ocean ridges in the global system; Mid Atlantic Ridge and the East Pacific Rise. The Mid Atlantic Ocean Ridge lies at the centre of the Atlantic Ocean, gradually spreading at a rate of 2 to 5 centimetres (0.8 to 2inches) per annum, forming a rift valley equal to the depth and width of the Grand Canyon.

On the other hand, the East Pacific Rise spreads faster at a rate of 6 to 16 centimetres (3 to 6 inches) per annum. No rift valley exists in the Pacific, and even a volcanic peak with a crack along the crest is present, and this feature is due to the fast-spreading rate. In ultra-slow spreading mid ocean ridge, the topography is more rugged; tectonic features are more dominant than volcanic activities. Scientists study the dynamics, chemistry, and biology of mid ocean ridge to gain insight into the fundamental yet surprising mechanism of the blue planet. Mid ocean ridge examples are Mid Atlantic Ridge and the East Pacific Rise.

Mid Ocean Ridge Volcanoes

The mid ocean ridges are considered to be the earth's largest magnetic system; along divergent plate boundaries, magma is produced by decompression melting of upwelling mantles. Magma rising from the mid ocean ridge volcanoes gathers in a pool at the base of the crust. Dimensions of reservoirs can be tens of kilometres, shaping a huge reserve of magma. Mid ocean ridge volcanoes occur where two tectonic plates move apart, as the crack forms in the crust due to the shift of plates magma from the mantle gush up these cracks and erupt. Magma rises due to a decrease in pressure resulting in reducing the solubility of gaseous constituents like water and carbon dioxide.

The sudden expansion and release of volcanic gases from the rising magma result in a sudden explosion in mid ocean ridge volcanoes. When expanding magmatic gas is the main reason the eruption style of mid ocean ridge volcanoes closely relates to the magma composition.

Strombolian and Hawaiian eruptions mainly consist of basalt, whereas Vulcanian and Plinian eruptions usually consist of intermediate and felsic magma. Intermediate and felsic magma is more viscous than basaltic magmas because of its chemical composition and lower temperature. Low viscosity allows gas to move and escape from the magma lowering the inbuilt pressure necessary for explosive gas discharge. In high viscosity, the gas bubbles get trapped, increasing the build-up pressure in the magma.

Mid Ocean Ridge Location

Mid ocean ridge occurs at divergent zones where oceanic plates are born, torn apart from the central valley or axis through. It is one of the oceanic relief features; by definition, mid ocean ridge is an undersea mountain range formed by tectonic activities. It consists of two ranges of mountains with a deep valley within.

Mid Ocean Ridge Facts

The length of global oceanic ridges is around 80,000 kilometres or 49,700 miles, out of which nearly 65,000 kilometres are continuous. The depth of the mid ocean ridge at the spreading centre is 2600 metres or 8500 feet. Plate tectonic boundaries connect all mid ocean ridges forming the oceanic ridge. In every ocean on the earth, there is a single integrated mid ocean ridge, a technically longest mountain range of the earth. Mid Atlantic Ridge is the first discovered mid ocean ridge. Frequent earthquakes and volcanism are signs of how oceanic ridges are identified.

Conclusion

Mid ocean ridges; large mountain ranges occur along seafloor spreading. The Mid Atlantic Ridge divides the North American Plate from Eurasian Plate and the South American Plate from the African plate. Seafloor spreading is a geological process where tectonic plates large portions of the earth's lithosphere split from each other due to mantle convection.

FAQs on Mid Ocean Ridges

1. What is the Mantle?

Ans: Mantle lies between earth’s extremely heated dense core and crust (thin outer layer), which is a mostly solid mass. Mantle mass is around 84% of the earth's volume with a dimension of 2,900 kilometres (1,802 miles). During the formation of the earth, iron and nickel were segregated from other rocks and minerals to shape the core of the planet. The molten material that encases the core was the early mantle. Over millions of tears through the process of outgassing, the mantle cooled as trapped water erupted with lava. As more water was released, the mantle solidified. Major constituents of the mantle are silicates, a spectrum of compounds with oxygen and silicon structure.

2. What is Mantle convection?

Ans: Seal floor spreading and other tectonic activities are caused by mantle convection. It is a slow roiling process of the earth's mantle. From the lower mantle and core, the heat is carried to the lithosphere by convection current. Thermal convection in the mantles (the layer between crust and core) where hot substances rise, cold materials sink the resultant flow governs the tectonic and volcanic activities. This process cools the entire planet and segregates chemicals. All planetary bodies preserve some heat inside, but the surface cools inevitably. The earth's surface is relatively cooler than the interior; thus go through mantle convection, where hot materials rise and cold, dense materials sink.

3. What is the East Pacific Rise?

Ans: The East Pacific Rise is a typical example of a fast-spreading mid ocean ridge; this ridge has been comprehensively studied over four decades for its abundance of hydrothermal vents. At these vents, scientists are investigating the association between crustal accumulation, mantel flow, hydrothermal, volcanic, and biological processes that cause a physical and chemical change of matter and energy between the ocean floor and the earth's mantle. Specifically, a region named 9 North, nine hundred kilometres away from the coast of Acapulco, Mexico, where repeated seafloor volcanoes along the mid ocean ridge is observed.