Study may solve age-old mystery of missing chemicals from Earth's mantle

Dec 05, 2007

Observations about the early formation of Earth may answer an age-old question about why the planet’s mantle is missing some of the matter that should be present, according to UBC geophysicist John Hernlund.

Earth is made from chondrite, very primitive rocks of meteorites that date from the earliest time of the solar system before the Earth was formed. However, scientists have been puzzled why the composition of Earth’s mantle and core differed from that of chondrite.

Hernlund’s findings suggest that an ancient magma ocean swirled beneath the Earth’s surface and would account for the discrepancy.

“As the thick melted rock cooled and crystallized, the solids that resulted had a different composition than the melt,” explains Hernlund, a post-doctoral fellow at UBC Earth and Ocean Sciences.

“The melt held onto some of the elements. This would be where the missing elements of chondrite are stored.”

He says this layer of molten rock would have been around 1,000 km thick and 2,900 km beneath the surface.”

Published in today’s edition of the journal Nature, Hernlund’s study explores the melting and crystallization processes that have controlled the composition of the Earth's interior over geological time. Co-authors are Stéphane Labrosse, Ecole Normale Superieure de Lyon and Nicolas Coltice, Université de Lyon.

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, Hernlund’s evolutionary model 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.

Source: University of British Columbia

Explore further: Evolution of the Antarctic ice sheet

Related Stories

Probing iron chemistry in the deep mantle

May 15, 2015

Carbonates are a group of minerals that contain the carbonate ion (CO32-) and a metal, such as iron or magnesium. Carbonates are important constituents of marine sediments and are heavily involved in the ...

Earthquakes reveal deep secrets beneath East Asia

May 14, 2015

A new work based on 3-D supercomputer simulations of earthquake data has found hidden rock structures deep under East Asia. Researchers from China, Canada, and the U.S. worked together to publish their results ...

Supercycles in subduction zones

May 06, 2015

When tectonic plates collide, they produce earthquakes like the recent one in Nepal. Researchers at ETH Zurich are providing new ways to explain how and why earthquake supercycles occur in zones where one ...

Recommended for you

Satellites catch the birth of two volcanic islands

1 hour ago

The birth of a volcanic island is a potent and beautiful reminder of our dynamic planet's ability to make new land. Given the destruction we've seen following natural events like earthquakes and tsunamis in t ...

Uncovering diversity in an invisible ocean world

2 hours ago

Plankton are vital to life on Earth—they absorb carbon dioxide, generate nearly half of the oxygen we breathe, break down waste, and are a cornerstone of the marine food chain. Now, new research indicates ...

Evolution of the Antarctic ice sheet

4 hours ago

ULB study sheds a new light on the stability of the Antarctic ice sheet. It shows for the first time that ice rises (pinning points that keep the floating parts of ice sheets in place) are formed during the transition between ...

Severe ozone depletion avoided

23 hours ago

We are already reaping the rewards of the Montreal Protocol, with the ozone layer in much better shape than it would have been without the UN treaty, according to a new study in Nature Communications.

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

brant
1 / 5 (3) Dec 05, 2007
"why the planets mantle is missing some of the matter that should be present,"

Is an assumption that your model accurately represents reality.

Obviously it doesnt.
Time to look at your model instead of forcing some other results to fit your models lacking.
out7x
2 / 5 (3) Dec 06, 2007
Petrology is a major field of study in geology.
Trippy
5 / 5 (1) Jan 24, 2008
Yeah... Imagine the audacity of suggesting that the melted area might have been bigger then previously expected, the sheer nerve of someone suggesting that mixing might have occured in a liquid, and that differential crystalization might actually have occured.

(For anyone who's in doubt - Wiki's page on it http://en.wikiped..._melting )

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.