Scientists find first ever evidence of asteroids with Earth-like crust

January 8th, 2009 - 2:49 pm ICT by ANI  

Washington, Jan 8 (ANI): A team of scientists has found the first ever evidence of asteroids with an Earth-like crust.

A research team, primarily composed of geochemists from the University of Maryland, US, estimated that two rare meteorites found in Antarctica two years ago are from a previously unknown, ancient asteroid with an outer layer or crust similar in composition to the crust of Earths continents.

This is the first ever finding of material from an asteroid with a crust like Earths. The discovery also represents the oldest example of rock with this composition ever found.

These meteorites point to previously unrecognized diversity of materials formed early in the history of the Solar System, according to researchers.

What is most unusual about these rocks is that they have compositions similar to Earths andesite continental crust - what the rock beneath our feet is made of, said first author James Day, who is a research scientist in Marylands department of geology. No meteorites like this have ever been seen before, he added.

According to Day, his team focused their investigations on how such different Solar System bodies could have crusts with such similar compositions.

We show that this occurred because of limited melting of the asteroid, and thus illustrate that the formation of andesite crust has occurred in our solar system by processes other than plate tectonics, which is the generally accepted process that created the crust of Earth, he said.

The two meteorites (numbered GRA 06128 and GRA 06129) were discovered in the Graves Nunatak Icefield during the US Antarctic Search for Meteorites (ANSMET) 2006/2007 field season.

Day and his colleagues immediately recognized that these meteorites were unusual because of elevated contents of a light-colored feldspar mineral called oligoclase.

Our age results point to these rocks being over 4.52 billion years old and that they formed during the birth of the Solar System. Combined with the oxygen isotope data, this age points to their origin from an asteroid rather than a planet, said Day.

Our studies of the GRA meteorites suggest similar crust compositions may be formed via melting of materials in planets that are initially volatile- and possibly water-rich, like the Earth probably was when if first formed, said Day.

A major uncertainty is how evolved crust formed in the early Solar System and these meteorites are a piece in the puzzle to understanding these processes, he added. (ANI)

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