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A thorough analysis of the composition and age of the rocks revealed that a meteorite, found in the sands of the Algerian desert, may be older than Earth and volcanically formed.
The meteor, known as Erg Chech 002, could be part of the crust of an object called a protoplanet.
As such, it represents a rare opportunity to study the early stages of the formation of the planets and to learn about the conditions of the early days of the solar system, when the planets were still forming.
EC 002 was found in May of last year, in the form of several pieces of rock with a total weight of 32 kg in the sand sea of Erg Chech in southwest Algeria. It was quickly identified as unusual; Instead of the cartilage composition of most recovered meteorites – which forms when chunks of dust and rock stick together – its texture was igneous, with crystalline inclusions of pyroxene.
It was therefore classified as an achondrite, a meteorite made from what appears to be volcanic material, which originated from an object that had undergone internal fusion to distinguish the core of the crust – a primitive planet, one intermediate stages in the formation of the planet.
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Of the tens of thousands of meteorites that have been identified, only a few thousand – 3,179, according to the Meteorite Bulletin – are chondrites.
Most of these chondrites come from one of the two original bodies, which is in a basaltic formation. This means that he cannot tell us much about the diversity of protoplanets in the early solar system.
In contrast, EC 002 is not basalt, but a type of igneous rock known as andesite, and was identified by a team of scientists led by geochemist Jean-Alex Barratt, from the University of Western Brittany in France.
The radioactive decay of the isotopes of aluminum and magnesium indicates that these two metals crystallized about 4.565 billion years ago, in the parent body which accumulated 4.566 billion years ago. As for the context, the Earth is 4.54 billion years old.
“This meteorite is the oldest of the volcanic rocks that have been analyzed so far, and it highlights the formation of primitive crusts that covered the oldest protoplanets,” the researchers wrote in their article.
And unlike basalt, which is formed by the rapid cooling of lava rich in magnesium and iron, andesite is mainly composed of silicates rich in sodium, and on Earth, at least, it forms in subduction zones, where the edge of a tectonic plate is pushed below.
Although it is rarely found in meteorites, the recent discovery of andesites in meteorites found in Antarctica and Mauritania has prompted scientists to study how it occurs. Experimental evidence suggests that it could form from the fusion of the cartilaginous substance.
Because cartilage bodies are so common in the solar system, protoplanets with andesite scales can also be common. However, when the team compared the spectral properties of EC 002 – that is, how it interacts with light – with the spectral properties of asteroids, they found nothing in the solar system. which corresponds to the meteorite.
Because EC 002 is slightly older than Earth, it is possible that its proto-planetary siblings continued to build Earth through a node of denser material in the dust cloud orbiting the young sun.
While we have a pretty good idea of the birth of small planets, which develop over millions of years as boulders of rock and dust stick together, the details of the process are a bit vague.
The EC 002 represents a great opportunity to improve our understanding of how our home system comes out of the dust.
The research was published in PNAS.
Source: ScienceAlert
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