New discovery could help explain earth's origin

Washington, July 17 (ANI): Scientists still have doubts over the theory that Earth arose from the collision of asteroids, as its composition doesn't resemble that of meteoroids - the small particles that break off from asteroids.

The Earth's mantle-the layer between the planet's crust and core-is missing an amount of lead found in meteorites whose composition has been analyzed following impact with the Earth.

Much of the Earth is composed of rocks with a high ratio of uranium to lead (uranium naturally decays to lead over time).

However, according to standard theories of planetary evolution, the Earth should harbor a reservoir of mantle somewhere in its interior that has a low ratio of uranium to lead, to match the composition of meteorites.

But such a reservoir has yet to be discovered-a detail that leaves Earth's origins hazy.

Now researchers in MIT's Department of Earth, Atmospheric and Planetary Sciences have identified a "hidden flux" of material in the Earth's mantle that would make the planet's overall composition much more similar to that of meteorites.

This reservoir likely takes the form of extremely dense, lead-laden rocks that crystallize beneath island arcs, strings of volcanoes that rise up at the boundary of tectonic plates.

As two massive plates push against each other, one plate subducts, or slides, under the other, pushing material from the crust down into the mantle. At the same time, molten material from the mantle rises up to the crust, and is ejected via volcanoes onto the Earth's surface.

According to the MIT researchers' observations and calculations, however, up to 70 percent of this rising magma crystallizes into dense rock-dropping, lead-like, back into the mantle, where it remains relatively undisturbed.

The lead-heavy flux, they say, puts the composition of the Earth's mantle on a par with that of meteorites.

"Now that we know the composition of this flux, we can calculate that there's tons of this stuff dropping down from the base of the crust into the mantle, so it is likely an important reservoir," Oliver Jagoutz, an assistant professor of geology at MIT, said.

"This has a lot of implications for understanding how the Earth evolved through history," he said.

The study is published in Earth and Planetary Science Letters. (ANI)

Matches

MORE TOP STORIES TODAY

On Now: Rajasthan Royals vs Kings XI Punjab

On Now: Rajasthan Royals vs Kings XI Punjab

GAME 7, SHARJAH—Fifties from Watson, Samson power Rajasthan to a big score. More »

Royal test for Kings

Royal test for Kings

Preview — Clash of philosophies between Australia-centric teams More »

Have nothing to prove to anybody — Sehwag

Have nothing to prove to anybody — Sehwag

The Nawab of Najafgarh says a good run in IPL could help his chances of a comeback on India's tour to England in June. More »

Shastri in proposed IPL probe panel

Shastri in proposed IPL probe panel

Some members stressed on the need for proposing names with an "impeccable record and clean image". More »

Duminy steals first win for Delhi

Duminy steals first win for Delhi

Furious fifties by Duminy and Dinesh Karthik end a long losing streak for the Daredevils. More »

Five things England must do to bounce back

Five things England must do to bounce back

England have appointed a new head coach in Peter Moores. More »

AB, Parthiv seal Bangalore's second win

AB, Parthiv seal Bangalore's second win

Royal Challengers overcame a stutter to cruise to the small target they were set by Mumbai Indians. More »

‘Felt like helpless minority’

‘Felt like helpless minority’

Former BCCI treasurer Ajay Shirke says emotions got the better of Srinivasan and he tried to oversimplify things by calling Meiyappan an “enthusiast.” More »

No way back for Pietersen: ECB

No way back for Pietersen: ECB

Kevin Pietersen's hopes of reviving his international career appeared to end Saturday when ECB managing director Paul Downton said there was 'no way back'… More »

Srinivasan can attend BCCI meeting

Srinivasan can attend BCCI meeting

His status as president of TNCA makes him eligible to attend the Working Committee meeting on Sunday. More »

Maxwell carves his parallel universe

Maxwell carves his parallel universe

Glenn Maxwell seems to project an icy disdain when at the crease. Match situations rarely faze him and the bubble in which he plays excludes everyone … More »

The world record that nearly wasn't

The world record that nearly wasn't

Twenty years ago this week, Brian Lara became Test cricket's highest scorer, but he almost didn't make it. More »

Moores gets second stint as coach

Moores gets second stint as coach

In a two-year spell from 2007 to 2009, the 51-year-old Moores led England in seven Test series. More »

Bangladesh senior players to see shrink

Bangladesh senior players to see shrink

Bangladesh's senior players will have three sessions with a psychological skill development coach later this month More »

BCCI is not anybody’s property — Dalmiya

BCCI is not anybody’s property — Dalmiya

Dalmiya feels that Srinivasan’s ‘power hungry’ attitude isn’t helping matters. More »

Tough for bowlers: Saeed Ajmal

Tough for bowlers: Saeed Ajmal

The 36-year-old believes the T20 format and rule changes in 50-over matches have made a real difference. More »

KP ridicules idea of day-night Tests

KP ridicules idea of day-night Tests

Kevin Pietersen has ridiculed the idea of day-night Test cricket, saying the game would be so different to proper Test cricket that we will need a whole… More »

Rajasthan edge low-scoring thriller

Rajasthan edge low-scoring thriller

The bowlers restricted Hyderabad to 133 for 6 before Rahane and Binny took Rajasthan over the line. More »

Maxwell blitz takes Punjab home

Maxwell blitz takes Punjab home

The Kings XI batsman blasted a 43-ball 95 to help his team pull off a massive chase against Chennai Super Kings. More »

BCCI members want independent probe

BCCI members want independent probe

The board members are realising after the Supreme Court's observations that something has to be done — IS Bindra More »

'BCCI lacks leaders to take on Srini'

'BCCI lacks leaders to take on Srini'

Two former BCCI presidents, Shashank Manohar and Jagmohan Dalmiya, have reacted strongly to the news of the BCCI calling an emergent meeting on Sunday… More »

Delhi look for first points against confident Kolkata

Delhi look for first points against confident Kolkata

Preview — The threat of Sunil Narine looms large again. More »

Bangalore vs Mumbai: A battle of the big-hitters

Bangalore vs Mumbai: A battle of the big-hitters

Preview — Given the firepower in both line-ups, Dubai crowd may see another high-scorer More »

Yuvraj tees off to Sharjah's delight

Yuvraj tees off to Sharjah's delight

Yuvraj Singh was hardly convincing to begin with against Delhi, but a big dose of crowd support and a helping of poor bowling meant he had the opportunity… More »