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New Technique Has Revealed How Completely Wrong We’ve Been About What’s Going On In The Earth’s Mantle

by onMay 15, 2016
 

With much still to learn about what’s deep below the Earth’s mantle/crust and how it behaves, tracking and record data on something you can’t truly observe is extremely difficult. But a new technique has just changed all that.

The convective currents of the Earth’s mantle have now been successfully mapped for the first time ever. What geologists discovered is that past predictions were completely inaccurate and that the Earth’s convective currents are moving almost ten times faster than we previously thought.

“In geological terms, the Earth’s surface bobs up and down like a yo-yo.” – Mark Hoggard, geologist and lead author of the new paper

With the mantle of our planet being close to 2000 miles thick, we’ve never drilled more than a couple of miles into it. That leaves a lot of what we “know” about the center of our planet is calculated by indirect measurements. This leaves a lot of room for error and inaccuracies.

“In addition to the normal plate tectonics, the interior of the plates which should be quite boring are being forced up and down by mantle convection. People have known that this occurs for a long time, but for the past 30 years we haven’t had the data to measure it.” – Mark Hoggard to Gizmodo

With only a “theory” about mantle convection currents, it’s no wonder that we vastly misunderstood them for the past 30 years. Thankfully, a new technique has been developed which allows up to accurately map these previously mysterious Earthly movements.

Know as ‘seismic reflection profiling’, the new technique allows geologists to observe well below the Earth’s crust. As Earth’s seismic waves travel downwards, geologists can measure their reflection and refraction and monitor what is happening at depths much lower than we can currently drill. This new method has the potential to uncover many changes to the depths of our Earth as well as teach us more about what’s going on down there.

Hoggard  and his team of geologists used the technique on over 2,000 seismic waves throughout the world. His and his colleagues work eventually allowed them to construct the first global database of mantle convection. Something that can teach us incredible things about our floating marble.

Among their early findings is the discovery of frequent changes in the thickness of seafloor crust. This in turn means that mantle convection, previously believed to be slow moving, is actually happening at a much faster rate than we thought. Researchers say that it’s almost like the sea floor is bubbling.

This insight into Earth’s deep interior can help explain all sorts of things closer to home. The formation of oil reserves, for instance, relies on the burial and compression of sediments that are chock full of decaying organic matter. These motions help control how quickly rocks containing organics are buried and cooked into oil. – Hoggard

We've Been Completely Wrong About What's Going On inside The Earth's Mantle

(Image: DPD)

Mantle convection can also have a surprising impact on Earth’s climate, by affecting the large-scale ocean circulation patterns that move heat around the world. The Gulf Stream, for instance, carries warm water from the Gulf of Mexico to the coast of western Europe, before chilling out and sinking around Iceland.

“There are these narrow channels around Iceland that allow water to sink. If you elevate or depress them, you could really affect ocean circulation.” – Hoggard

Finally, mantle convection is responsible for forming geothermal systems, like Yellowstone, and island archipelagos, like Hawaii, that crop up in the middle of tectonic plates. Hoggard’s findings will shed light on how and why parts of the crust located far from plate boundaries are rising, falling, and cooking.

“It’s really a shift in view point. A lot of geologists will look at places far away from plate boundaries and think they should be very stable. What we’ve shown is that regions that are often ignored are probably very active.”

References: Nature GeoscienceUniversity of CambridgeGizmodo

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