Scientists deny “older impact crater on earth”

The discovery of an old meteorite impact crater was recently reported in the remote region of Pilbara in western Australia. The original study, done by a different group, made headlines with the statement that the crater graduated 3.5 billion years ago. If it were true, it would be by far the oldest on earth.

A new investigation team, exploring the same place says that although it agrees that this is the place of an old impact of meteorite, It came to different conclusions About your age, size and meaning. These results were in Science Advances.

An impact crater, two versions of events

According to the planetary scientists seek old impacts to learn about the Initial Earth Formation.

So far, no one has found an older impact crater than the Yarrabubba structure, with 2.23 billion yearsalso in Australia. (Some of the authors of both Pilbara 2025 studies were co -authors of the Yarrabubba study of 2020.)

The new candidate is located in an area called North Pole Dome. It is a warm, hot, spotted baron.

The first report on the new crater said it formed 3.5 billion years ago and had more than 100 kilometers in diameter. It was proposed that such a large impact could have played a role in the formation of the continental crust in Pilbara. The investigators also suggested that it could have influenced primitive life.

The new team also determined that the crater was much smaller – about 16 km in diameter. According to these investigators, this impact was too young and small to influence continents formation or primitive life.

How can two studies come to such different conclusions?

The originally circular crater is deeply eroded, leaving only subtle evidence in the landscape. However, among the rusty basalts there are unique signs and meteorite impact revealing: fracture cones.

Fracture cones are distinct fossilized impressions of shock waves that passed through the rocks. Its unique conical forms are formed under brief but immense pressures, where a meteorite reaches the earth.

Both studies have found fracture cones and agree that the site is an old impact. The new study concludes that the impact actually happened much later, At some point after 2.7 billion years. That is at least 800 million years younger than the previous estimate.

This new crater also needed a name. The new team consulted the local Aboriginal, the Nyamal, who shared the traditional name for this place and their people: Miralga. The name “Miralga Impact Structure”Recognizes this inheritance.

A impact age was estimated by field observationssince none of the studies found material that could provide an age of impact by radiometric dating – a method that uses radioactive isotope measurements.

Both studies applied a geological principle called overlapping lawwhich states that the rock layers deposit each other over time, so the rocks at the top are younger than those below.

The first group found fracture cones inside and below a sedimentary layer that is known to have been deposited 3.47 billion years ago, but did not find cones in younger rocks above this layer, which meant that the Impact occurred during the deposition of the sedimentary layer.

Your observation seemed to be the “irrefutable proof”For an impact 3.47 billion years ago. As it turned out, there was more for history.

The new investigation found fracture cones in the same rocks of 3.47 billion, but also in younger rocks that covered them, including lavas that is known to have erupted 2.77 billion years ago.

The impact had to occur after the formation of the younger rocks that contained fracture cones, ie some time after the 2.77 billion years old.

At the moment, not the recent team doesn’t know exactly how young the crater is. Investigators say they can only limit the impact to have occurred between 2.7 billion and 400 million years ago. “We are work to date the impact by isotopic methodsBut these results are not yet available, ”they say.

“We made the first map showing where the fracture cones are located. There are hundreds in an area of 6 km in diameter. From this map and its guidelines, we estimated that the original crater was about 16 km in diameter. A 16 km crater is very different from the original estimate of over 100 km. It is too small to have influenced the formation of continents or life. At the time of the impact, the Pilbara was already quite old”.

A new connection to Mars

Science is a self-regulated sport. Discovery claims are based on the data available at the time, but often require modifications based on new data or observations.

Although not the oldest in the world, the Miralga’s impact is scientifically uniquesince basalt formed craters are rare. Most basalts formed there are 3.47 billion years, which makes them Older target rocks that suffered shock.

Before the impact, these old basalts had been chemically altered by seawater. Nearby sedimentary rocks also contain the oldest older fossils on Earth. Rocks like this probably covered much of the primitive land and Mars.

This makes Miralga’s impact structure a training ground for planetary scientists who study Mars’s characterized (and perhaps primitive life) surface. It is a place easily accessible to test instruments and images of Exploration of Mars, even here on Earth.