Recognizing the sites of meteorite impacts may seem easy, as giant craters on Earth’s surface show where these distant objects finally stopped abruptly. But this is not always the case.
Sometimes these scars are healed, hidden by layers of dirt and vegetation, or re-smoothed by the elements over long periods of time. Scientists have now found a way to discover these hidden impact sites.
Think of a large piece of space rock approaching its final destination on Earth. Meteorites can enter Earth’s atmosphere At 72 kilometers per second (160,000 miles per hour), but it started to slow down as it moved through our relatively dense atmosphere.
Beautiful light in the sky when the meteor flies because of ‘eradication‘- where the meteor’s layers and layers evaporate via high-speed collisions with air molecules.
Then, if the space rock collides with the Earth, it collides with the Earth forming break cones, Impact craters and other signs that a meteorite struck here.
This is an intense geological process, with high temperatures, high pressures and fast particle velocities all synchronizing. One of the things that happens during this intense process is that the effect forms a plasma – a type of gas in which atoms are split into electrons and positive ions.
“And once there is contact at that speed, there is a change in kinetic energy into heat, steam, and plasma. Many people realize there is heat, and possibly fusion and evaporation, but people don’t think of plasma. “
What the team found here was that all of this plasma had a strange effect on the rocks’ natural magnetism, leaving an impact zone where the magnetism was about 10 times lower than the normal levels of magnetism.
residual natural magnetization It is the amount of natural magnetism present in rocks or other sediments.
When the sediments of the earth settled after their deposition, they were small Magnetic metal granules inside Align along the planet’s magnetic field lines. These grains then remain trapped in their directions within the hard rock.
That’s a very small amount of magnetization – about 1-2% of the “saturation level” of the rock, and you can’t tell with a regular magnet, but it sure is there and it can. It can be measured fairly easily by geological equipment.
However, when a shock wave occurs – such as during a meteorite impact – there is a loss of magnetism, as the magnetic grains receive a nice burst of energy.
“The shock wave provides energy in excess of the energy (>1 GPa for magnetite >50 GPa for hematite) needed to prevent magnetic residues in individual magnetic grains”, The researchers write in a new study.
Usually the shock wave passes and the rocks return to their original level of magnetism almost immediately. But as the team found in the 1.2 billion-year-old Santa Fe Effect Structure In New Mexico, magnetism never returned to its natural state.
Instead – they suggest – the plasma created a “magnetic shield” that kept the grains in their opposing state, and the grains simply randomly oriented. This caused the magnetic density to drop to 0.1 percent of the rock’s saturation level – a 10-fold drop from the normal level.
“We provide support for a newly proposed mechanism whereby the appearance of a shock wave can generate a magnetic shield that helps maintain magnetic grains in a supermagnetic-like state shortly after exposure, leaving individual grains magnetized in random directions, greatly reducing the overall magnetic density”, The team writes.
“Our data not only demonstrates how the impact process enables a reduction in the intensity of the Paleomagnetic, but also inspires a new direction of effort to study impact sites, using Paleo intensity reduction as one of the novelties. influence agent.”
Hopefully this new discovery means that scientists have another tool in their belts when it comes to finding impact sites, even those that lack natural signs of impact, such as cones or cones and pits.
The search was published in Scientific Reports.
“Proud explorer. Freelance social media expert. Problem solver. Gamer. Extreme travel aficionado.”