A recent study has challenged the notion that a crater in Western Australia is the world’s oldest, estimated to have formed 3.5 billion years ago. The new findings suggest an impact occurred between 2.7 and 400 million years ago, making it at least 800 million years younger than the original estimate.
The crater, known as Miralga, was discovered in the Pilbara region of Western Australia and was previously claimed to be the oldest impact crater on Earth. However, researchers from a different study group found subtle clues of an impact, including shatter cones, which are fossilized imprints of shock waves caused by meteorite impacts.
The initial study estimated the impact occurred 3.5 billion years ago, with a diameter of over 100 kilometers. However, the new research concludes that the crater was much smaller, around 16km in diameter, and too young to have influenced continent formation or early life.
The researchers used the law of superposition to estimate the impact age, which states that rock layers get deposited one on top of another over time, with rocks on top being younger than those below. However, their findings showed that shatter cones were present in both older and younger rocks, indicating an impact occurred after the formation of the youngest rocks.
The study’s authors acknowledge that they cannot precisely date the crater but believe it is likely between 2.7 billion and 400 million years old. The discovery has significant implications for planetary scientists studying Mars, as similar rocks have been found on the red planet, suggesting a connection between Earth and Mars.
While the Miralga impact structure is not the world’s oldest, it remains scientifically unique due to its age and composition. Further research is needed to confirm the findings and better understand this fascinating crater.
Source: https://www.livescience.com/planet-earth/geology/study-raises-major-questions-about-earths-oldest-impact-crater