Monday, December 26, 2016

Earth's mantle cools more quickly than was previously thought

Oceanic crust newly formed thinner than the old one, according to research. This indicates that the shell thinning earth cooled more quickly than was previously supposed

Studies have shown that the thickness of the newly volcanic crust has thinned over the last 170 million years. At a symposium of the American Geophysical Union, the researchers noted that this newly formed crust cooled two times faster than was previously thought.

This process provides valuable information about how the tectonic plates moderates internal temperature of the planet, according to Harm Van Avendonk, co-author of the study and a geophysicist at the University of Texas at Austin.

The discovery is fascinating, although more information is missing because oceanic crust thickness measurement requires seisimice studies. It also may explain why such supercontinents Pangea broke.

The shell is made up of rock earth hot (500-900 ° C at the top), under high pressure. When this material rises to the earth's surface, the pressure drops and rock begins to melt. This material may ascend to the surface by ocean rifts and build new crust. When the jacket temperature is higher, thicker crust is formed.

Comparing now the crust of 170 million years ago it was noticed that the old one is thicker by 1.7 km. The chemical analysis shows the lava rocks in that the mat formed was cooled to 6-11 degrees per 100 million years in the past 2.5 billion years. But the average Jurassic (170 mil. Years), mantle cooled by an average of 15-20 degrees Celsius per 100 million years.

Researchers have hypothesized that the tectonic plates causes this cooling. By forming new crust and sinking tectonic plates, coat loses heat. It has been found that the mantle beneath the Pacific Ocean (area with little tectonic activity) was cooled to 13 degrees Celsius per 100 million years, and the sheath in the Atlantic was cooled to 37 ° C per 100 million years.

An important factor in temperature variation of the shell is the supercontinent. Atlantic and Indian Ocean have occurred due to breakage Pangaea. Before this process, the mantle underneath has been able to keep high temperature, due to the high thickness of continental crust. When breaking, ocean crust mantle beneath the newly cooled quickly, while lowering the temperature of the mantle beneath the Pacific Ocean remained constant.

Also, the accumulation of heat beneath the continental crust (as if Pangaea) in a long time, breaking them. Laurent Montesi, a scientist at the University of Maryland, says that "this may explain why a continent breaks after 100 million years."




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The above post is reprinted from materials provided by  Science News . Note: Materials may be edited for content and length.

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