The impact of an asteroid that about 65 million years ago caused the extinction of the dinosaurs is an event now known also outside of the scientific field. However, a study published in the journal “Geochemistry, Geophysics, Geosystems” reconstructs the impact of a much larger asteroid, with a diameter estimated to be between 37 and 58 km (23 to 36 miles), occurred about 3.26 billion years ago.
Donald Lowe, a geologist at Stanford University and co-author of the study, made a discovery in the region of South Africa known as the Barberton greenstone belt. There, some of the oldest exposed rocks on Earth and some of the oldest traces of life wer found. In that area, Lowe found rock formations which bore the traces of the impact of an asteroid such as a layer of iridium, an element rare on Earth but abundant in many asteroids.
In the solar system’s early life, there was a period called the late heavy bombardment in which a significant amount of asteroids hit the inner planets and therefore the Earth and the Moon too. Generally, this period is extended between 4.1 and 3.8 billion years ago but that doesn’t mean that when it ended impacts of asteroids ceased. It’s possible that there was a sort of late tail in which the asteroid object of the study struck the Earth.
The research on the impact occurred about 3.26 billion years ago was conducted also through simulations that gave the authors an idea of what happened. The conclusions are that the asteroid caused a catastrophe on a planetary scale and strong repercussions at tectonic level.
The crater caused by an asteroid impact that occurred at a speed of around 20 km/s (12 mps) might have had a diameter of around 500 km (about 300 miles). The other consequences according to the researchers wer an earthquake of magnitude 10.8 with a direct impact on a global level causing several earthquakes. There were also huge tsunamis, at least in the waters that didn’t boile due to the heat generated by all the energy released following the impact.
The physicist Norman Sleep of Stanford University used physical models to guess the characteristics of the impact by comparing the available data with those of other earthquakes and impacts on the Earth and the Moon. Thus Sleep reconstructed the way in which the waves traveled from the site of the impact creating the geological formations of the Barberton greenstone belt.
The traces of the crater itself may have disappeared despite its size because in more than three billion years the geological activity may have changed the area completely. It’s an important research to better understand the history of the Earth in its earliest stages, including those in which life originated and developed.
[ad name=”eBayUSUKAstronomy”]
