Saturday, January 6, 2018

Puzzling patches in Earth’s interior billions of years in the making, Stanford researchers find


Scientific Anomaly – Insights to Deep Processes of Earth

According to Stanford researchers, chemical reaction with ancient seawater and iron in mantle over eons of the Earth illuminates the formation of mysterious blobs in the interior of the planet which tends to damp down passing seismic waves.

Scientists have been confused for decades, with these thin patches of dense rock which have been placed around 1,800 miles below the surface of the Earth, just above the core-mantle boundary which seems to isolate the molten metal heart of the planet from its rocky shell. They tend to be prominent from their surroundings since the seismic waves created by earthquakes tend to slow down by a tenth to a third of their usual speed when they sweep across.

These dampening zones, apart from being a scientific anomaly, could also offer insights in the other deep processes of the Earth according to research leader, Wendy Mao, an associate professor of geological sciences at School of Earth, Energy & Environmental Sciences of Stanford.

The information regarding the regions considered as ultra-low velocity zones or ULVZs takes place at the core-mantle boundary tends to be interesting since it recommends that the core and mantle of the Earth tends to interrelate to a much greater extent than had been earlier valued.

ULVZs – Origins of Molten Plumes 

According to Mao there is evidence that ULVZs are the origins of molten plumes which tend to feed volcanoes towards the surface and hence ULVZs could indicate a considerable amount of cycling between the core, mantle and surface of the Earth than speculated. The composite as well as the origins of the zones tend to remain a unknown owing to their extreme depths.

 However in the latest researcher published online in the journal Nature, which is an international team of researchers headed by Mao, have provided a new theory explaining how they tend to be formed. The device which has been proposed by them is established on their latest discovery of a novel kind of oxygen-rich iron compound which is inclined to form spontaneously in great heat and pressure, conditions which are present in the lowermost mantle region of the Earth.

Mao’s team while experimenting in the lab at Argonne National Laboratory in Illinois, had compressed slivers of iron foil suspended in pure water to around 90 gigapascals or about 900,000 times the pressure at sea level laser heating them to 3,000-4,000 degrees Fahrenheit.

Super-Oxygenated Iron 

The consequence of this is a super-oxygenated type of iron which is packed with around a third more oxygen molecule than the most oxygen rich oxides which tend to occur beneath the surface conditions. The team also portrayed that their compound shares several of the seismic waves dampening properties shown by the low velocity zones.

Jin Liu, study first author, a postdoctoral researcher in the lab of Mao stated that the low sound speeds calculated for compound tend to match precisely to what was observed seismically in ULVZs. Moreover, the oxygen-rich iron created by the team in the lab had the tendency to form easily at the core-mantle boundary.

Mao commented that this reaction needed only iron and water and as long as one has these components and the accurate temperature together with pressure conditions, this compound tend to form.

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