Plate Tectonics

Earth’s collection of interlocking plates is unique in the solar system. Scientists connect it to our planet’s other special features, such as its stable atmosphere, protective magnetic field and the abundance of complex life. 

But geologists have long debated exactly when Earth’s crust broke into plates, with estimates ranging from the first billion years of the planets 4.5 billion year history to sometime in the last billion. 

The actions of tectonic plates shapes far more than just geography. The recycling of Earth’s surface helps to regulate its climate, while the building of continents and mountains releases vital nutrients into the ecosystem.

Plate tectonics holds that the Earth’s outer shell is fragmented into continent-sized blocks of solid rock, called “plates”, that slide over Earth’s mantle. New supercomputer modelling has shown that the plates on which Earth’s oceans sit are being torn apart by massive tectonic forces even as they drift about the globe.

The asthenosphere – which is derived from the Greek asthenes, meaning weak – is the uppermost part of the Earth’s mantle, right below the tectonic plates that make up the solid lithosphere. Traditionally, the asthenosphere has been viewed as a passive region that separates the moving tectonic plates from the mantle. 

Studies suggest that the asthenosphere may play a more active role as the source of heat and magma responsible for volcanoes occuring within the interior of a tectonic plate. In addition, the asthenosphere may have a major impact on plate tectonics and the pattern of mantle flow. 

Convection simulations show that this region is hotter than expected and this has renewed interest in the asthenospheres role in Earth’s engine. Evidence also suggests that the asthenosphere is hotter than the mantle below it. This increase in temperature can reduce the mechanical strength and eliminate the need to bring heat directly from the Earth’s core to the asthenosphere to explain volcanic activity at hot spots

Diamonds that formed deep in the Earth’s mantle contain clues of chemical reactions that occurred on the seafloor and can help geoscientists understand how material is exchanged between the planet’s surface and its depths.

A new study published in Science Advances confirms that serpentinite – a rock that forms from peridotite, the main type of rock in Earth’s mantle, when water penetrates cracks in the ocean floor – can carry surface water as far as 700 kilometers deep by plate tectonics.

During subduction, nearly all tectonic plates that make up the seafloor eventually bend and slide down into the mantle, which can recycle surface materials such as water, into the Earth.

Scientists from Cambridge University and NTU Singapore have discovered that slow-motion collisions of tectonic plates drag more carbon into Earth’s interior than previously thought.

They found that the carbon drawn into Earth’s interior at subduction zones. Tends to stay locked away at depth, rather than resurfacing in the form of volcanic eruptions. Their findings suggest that only one third of carbon recycled beneath volcanic chains returns to the surface via recycling, in contrast to previous theories that what goes down mostly comes back up.

One of the ways to combat climate change is to find ways to reduce the amount of CO2 in Earth’s atmosphere. By studying how carbon behaves in the deep Earth, which stores the majority of our planet’s carbon, scientists can better understand the entire lifecycle of carbon on Earth, and how it flows between the atmosphere, oceans and life at the surface.