A new look at the mysterious layer of the earth's surface

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March 20, 2013. Mysterious layer lies beneath the earth's surface tectonic plates.

Sandwiched between two layers of rock — a rigid lithosphere and the asthenosphere is more plastic — it's a fine line like a jelly in a sandwich with peanut butter. Scientists believe that it may be saturated with moisture rock breed or partially molten rock, but there is no consensus.

"There are a lot of conflicting points of view," — said Kerry Kay, a seismologist from Scripps Institution in San Diego.

Understanding the nature of the boundary layer and its role in plate tectonics — one of the most important issues in seismology, according to the list of collected at the meeting of the Association of Research Institutes of Seismology (IRIS) in 2009.

The new scientific work, coauthored by Kay argues that frontier layer consists of molten magma, at least under ocean bottom. Off the coast of Nicaragua, under the Cocos tectonic plate and the researchers found a layer of partially molten rock thickness of 25 kilometers. The results were published March 20 in the journal Nature.

"A real surprise — said Nayf Semer, a graduate of Scripps and lead author of the work. — We went to investigate Fluid cycle of crustal rocks in a subduction zone, and stumbled on a partially molten boundary layer. "

see also discovered an unusual volcano near Mexico

In the past decade has been the main version that frontier layer probably is not blown, but weakened with water saturated with minerals, said Nayf. The scientific work of the last five years, based on the study of volcanic waves passing through layer, suggest that it is molten, at least in some areas.

The researchers found molten layer beneath the Cocos plate when using equipment designed to search for subtle changes in the electromagnetic fields of natural origin. These changes help to determine the structure under the surface and are very effective to seek to volumes of liquids such as oil and gas reservoirs.

"We received electromagnetic data is quite indicative of the objects of this kind, — said Nayf. — Perhaps we could say much more [about the boundary layer] if I did more research, "- he said OurAmazingPlanet.

Lithosphere-asthenospheric boundary (LAS) is the basis of rigid tectonic plates that move over the surface of the Earth's crust on the Earth's mantle flows. Both layers are composed of rock, but the lithosphere is strong, rigid and cold, while more hot asthenosphere flow and deformation on the scale of geological time. Layer between them, molten or not, lies at a depth of 50 km beneath the ocean floor and 200 km beneath the continents.

The next step — to explain how there came from the magma, said Kay. Some studies have suggested that more ancient oceanic lithosphere is not molten LAS Nayf added. Magma could "stick" to the bottom of the geologically younger Cocos plates since its formation in the nearby spreading ridge.

Translation: Anastasia Antoshkina
Source: Live Science

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