A piece of meteorite found in the desert sands of Algeria could be a piece of a planet that has never succeeded.
According to a thorough analysis of the composition and age of the rock, the meteorite known as Erg Chech 002 is older than Earth, it formed volcanically – suggesting that it may have once been part of the crust of an object known as a protoplanet. .
As such, it is a rare opportunity to study the early stages of planet formation and learn more about the conditions of the early days of the solar system, when the planets we know and love today were still forming.
CE 002 was just found in May last year, several pieces of stone with a combined weight of 32 kilograms (70 kilograms) in the sandy sea Erg Chech in southwestern Algeria. He was quickly identified as unusual; rather than the chondritic composition of most recovered meteorites – which form when pieces of dust and rock stick together – its texture was magmatic, with inclusions of pyroxene crystals.
Therefore, it was classified as achondrite, a meteorite made of what appears to be volcanic material, originating on a body that has undergone internal melting to differentiate the crust core – a protoplanet, one of the middle stages of planet formation.
Of the tens of thousands of meteorites that have been identified, only a few thousand – 3,179, according to the weather report database – are acquitted.
Most of these achondrites come from one of the two parent bodies and have a basaltic composition. This means that they cannot tell us much about the diversity of protoplanets in the early solar system.
CE 002, on the other hand, is not basaltic, but a type of volcanic rock known as andesite, established by a team of scientists led by geochemist Jean-Alix Barrat from the University of West Brittany in France.
Of all the meteorites we have found so far, even among chondrites, which makes EC 002 extremely rare – and opens a new way of understanding the formation of the planet.
According to the team’s analysis, the rock is old. The radioactive decay of the isotopes of aluminum and magnesium suggests that these two minerals crystallized about 4.565 billion years ago, in a parent body that accumulated 4.566 billion years ago. For context, the Earth is 4.54 billion years old.
“This meteorite is the oldest igneous rock analyzed so far and sheds light on the formation of primordial crusts that covered the oldest protoplanets,” the researchers wrote in their paper.
Unlike basalt, which is formed from the rapid cooling of lava rich in magnesium and iron, andesite is composed mainly of sodium-rich silicates and – at least on Earth – is formed in subduction zones, where the edge of a tectonic plate is pushed. below. another.
Although rarely found in meteorites, the recent discovery of andesite in meteorites found in Antarctica and Mauritania has led scientists to investigate how it might occur. Experimental evidence suggests that it may form from melting chondritic material.
Because chondritic bodies are so common in the solar system, it is possible that the formation of protoplanets with andesite crusts is also common. However, when the team compared the spectral characteristics of EC 002 – that is, how it interacts with light – with the spectral characteristics of asteroids, they could not find anything in the Solar System that matched the meteorite.
Andesitic crustal remains are not uncommon in meteorite records; they are also rare in the asteroid belt. Which begs the question: if the formation process was so simple and common, then where the hell did all the differentiated protoplanets end up?
In the same place, most of the material in the solar system probably arrived: either they were sprayed or incorporated into larger rocky bodies; or, perhaps, a combination of both.
Since EC 002 is slightly older than Earth, it is even possible that its protoplanetary siblings are helping to build the Earth from a node of denser material in the dust cloud that orbited the baby Sun.
Although we have a pretty decent understanding of how baby planets are born, growing over millions of years as agglomerations of rocks and dust stick together, the specifics of the process are a little more mysterious.
EC 002 is a spectacular opportunity to adjust our understanding of how our home system came out of the dust.
The research was published in PNAS.