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Earth’s longest mountain chain

This mid-ocean ridge, formed by tectonic plates, is known as the 70,000 km-long volcano that runs through the dark recesses of all the world’s oceans, girding the globe. It is the planet’s largest magmatic system, with a seafloor terrain more varied and spectacular than almost anything found on dry land, with a collection of volcanic ridges. There is a long rift of valleys, fault zones, and other geologic features, including giant fields of gushing hot springs that shed tons of minerals into icy seawater, creating eerie mounds and towers that can be rich in metals like gold and silver.

The vast majority of volcanic activity on the planet occurs along the mid-ocean ridge, and this is where the crust of the Earth is born. The material that erupts is primarily basalt, the most common rock on Earth.

Earthquake swarms indicating an erruption has occured:

  • fresh-looking basalt,
  • plumes of hot chemical-laden water, and
  • recently-killed marine organisms

In places where spreading is occuring fastest (more than 80 millimeters, or 3 inches, per year), the ridge has relatively gentle topography and is roughly dome-shaped in cross-section as a result of the many layers of lava that build up over time. At the slower – or ultra-slow – spreading centers, the ridge is much more rugged, and spreading is dominated more by tectonic processes rather than volcanism.

There are three processes that contribute to the formation of new oceanic crust, with some uncertainty as to which is dominant.

Ridge-push – slab-pull – mantle conveyor.

  1. “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.
  2. At the subduction zone, “slab-pull” comes into effect. This is simply the weight of the tectonic plate being subducted (pulled) below the overlying plate dragging the rest of the plate along behind it.
  3. The “mantle conveyor” (asthenosphere) appears to have less influence as it is too plastic (flexible) to generate enough friction to pull the tectonic plate along.

As the oceanic slabs slowly pull apart, they give molten rock and gases an escape route. Experts believe this volcanic activity may carry major repercussions. The oceanic ridges account for some 70 percent of the planet’s volcanic eruptions, making them a significant source of heat and exotic minerals, and carbon dioxide, which all volcanoes emit.



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