More than 50 years ago, the Apollo program allowed us to validate the theory of its formation. solar systemsolar systemOn the one hand, showing that it is now known that the lunar craters were indeed impact craters and not volcanic structures (although some are)) And that these craters were originally bombarded by celestial bodies, as well as the moon’s oceans, for more than four billion years, the activity rapidly decreased and the bodies became smaller and smaller on average.
So it validated the idea that the planets were born. increaseincrease And, the snowball effect, in the key disc The matterThe matter Gradually passing through the state of dust and GazGaz for thatThe fetusThe fetus of planets in violent collision, such as in planetary formation LoanLoan Absolutely
Note that the Moon is believed to have formed from the debris of a giant impact about 4.5 billion years ago. Small planetSmall planet The size of Mars is called TheaThea and the young proto-Earth.
The cosmic bombardment also had a lot to release The heatThe heat During the impact, lava is generated.
The Barberton Greenstone Belt, a wonderful reminder of an early Earth
So we have every reason to think that, at the time of the Earth’s dedication, that is, about 4.56 to 4 billion years ago, our The blue planetThe blue planet There was, of course, a volcanic and chaotic world worthy of the Greek god of the underworld, Hades, with whom massive conflict took place. AsteroidAsteroid And CometComet. Between 4 billion and 2.5 billion years ago, during the Archean, everything was calm and it is believed that the ocean and life forms already existed.
This does not mean that there were not still catastrophic events capable of strongly affecting the habitability of the Earth and its biosphere. In fact, a recent publication in a well-known journal PNAS, Which we owe to a team of geoscience researchers led by Nadja Drabon of Harvard University demonstrates this well.
Nadja Drabon and her colleagues, like others before them, explored South Africa’s fabled Barberton region with similar rocks from the early and mid-Archean, part of a lesser-known “greenstone belt”. are, which are more popular in English. The world of geology under the name Barberton Greenstone Belt.
These are the metamorphosed remnants of the volcanic area associated with it. Sedimentary rockSedimentary rock Where, for years, researchers believe there have been clues to the existence of very ancient life forms The fig treealso called Fig tree groupA geological formation consisting of stromatolites with fossils of microscopic life is about 3.26 billion years old.
Just beyond this region flows the Komati River, which gave its name to the particularly fluid lavas that flowed there, more than three billion years ago, the Komati, and which have rarely flowed since the end of the Archean. are Their ViscosityViscosity Must be similar to water because they are flowing at temperatures over 1,400°C and maybe even over 1,600°C.
But what Nadja Drabon was interested in was investigating sedimentology, petrography and geochemistry. IsotopesIsotopes Of CarbonCarbon Sedimentary rocks from the S2 impact, a astroblemaastroblema Produced by an asteroid made of meteorite-like rocks called carbonaceous chondrites such as Allende.
gave Barberton Map Geotrail In Mpumalanga, South Africa, there is a 37 km scenic drive connecting Barberton and Swaziland. Interpretive panels and landscaped areas at key geological sites and observation points explain geological and rock formations, including the famous Greenstone Belt. To get a fairly accurate French translation, click on the white rectangle at the bottom right. Then the English subtitles should appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Auto-Translate”. Select “French”. © Bitbook program
A heat wave that takes the atmosphere to over 100°C!
On our blue planet, archaeological geological archives record at least 16 major impacts. Racing carsRacing cars More than 10 km in diameter. In the case of S2, it is estimated to be about 4 times the size of a celestial body.EverestEverestand probably 50 to 200 times its weight. Chicxulub craterChicxulub crater Associated with the disappearance of DinosaursDinosaurswhich crashed into Earth 3.26 billion years ago.
L’EnergyEnergy It dug a crater 500 km in diameter and generated so much heat that the atmosphere and ocean surface rose to over 100 °C over a few tens of meters, certainly accompanied by a massive tsunami about 66 million years ago. With a global shower of molten rock droplets in the Yucatán.
The sky would become black due to the released dust and particles. without the lightthe light Of SoleilSoleil Penetrating darkness, life on land or in shallow water, on which depends. PhotosynthesisPhotosynthesiswould have been destroyed.
There were only single-celled organisms at that time, but the table Nadja Drabon and her colleagues compiled from hundreds of kilos of rocks collected at Barberton and analyzed in the laboratory shows that life was remarkably flexible. Better yet, the effect is also in its favor. ContentContent of the celestial body which enriched the oceans with phosphorus.
Additionally, turbidity in these same oceans has brought material-rich material to the surface deposits. ferferwhich, again, accelerated the rebound in growth. MicroorganismsMicroorganisms. It was probably accompanied by other similar influences during the Archean.
Would our planet’s early ages have been unsuitable for life? Will there be nothing left in this hellish age? Are we sure? And then, how the “ball of fire” became the planet we know, covered in oceans… In 9 minutes, geologist Hervé Martin gives you the keys to decoding ancient Earth’s atmosphere. is © French Society of Exobiology
Nadja Drabon Presents own work and that of colleagues on S2. To get a fairly accurate French translation, click on the white rectangle at the bottom right. Then the English subtitles should appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Automatic translation”. Select “French”. © Alex Kovalik (PhD student) And Andre Becker (PI) at the University of Californiaby the river