New findings shed light on missing chemicals from earth’s mantle

December 6th, 2007 - 3:29 pm ICT by admin  

Washington, Dec 6 (ANI): New observations by geophysicists might shed light on the age-old mystery of missing chemicals from the Earth’s mantle.
The centre of Earth is a fiery core of melted heavy metals, mostly iron. This represents 30 per cent while the remaining 70 per cent is the outer mantle of solid rock.
Traditional views hold that a shallow ocean of melted rock (magma) existed 1,000 km below the Earth’s surface, but it was short lived and gone by 10 million years after the formation of Earth.
In contrast, a new evolutionary model by John Hernlund, a UBC (University of British Columbia) geophysicist, predicts that during Earth’s hotter past shortly after its formation 4.5 billion years ago, at least one-third of the mantle closest to the core was also melted.
“The partially molten patches now observed at the base of the Earth’s mantle could be the remnants of such a deep magma ocean,” said Hernlund.
“As the thick melted rock cooled and crystallized, the solids that resulted had a different composition than the melt,” explains Hernlund. “The melt held onto some of the elements. This would be where the missing elements of chondrite are stored,” he added.
“This layer of molten rock would have been around 1,000 km thick and 2,900 km beneath the surface,” said Hernlund.
Hernlund’s study explores the melting and crystallization processes that have controlled the composition of the Earth’s interior over geological time. (ANI)

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