Ancient asteroid clues in Pilbara rocks
An asteroid four times the size of Rottnest Island ploughing into Earth and gouging a crater the size of Victoria — it is the stuff of nightmares and it happened 3.46 billion years ago, according to findings from the Pilbara.
“The impact would have triggered earthquakes orders of magnitude greater than terrestrial earthquakes, it would have caused huge tsunamis and would have made cliffs crumble,” according to Dr Andrew Glikson, of Geoscience Australia.
This scenario comes about after tiny spherules, or glass beads, formed from vaporised rock during the impact were found in a core sample retrieved near Marble Bar.
The location of the asteroid impact is unknown.
“Marble Bar is one of the very few areas of the world where sedimentary rocks of this great age are preserved, and where the rocks are so precisely dated,” says Dr Arthur Hickman, of the Geological Survey of WA.
This impact is the second oldest so far discovered. “The oldest recorded impact occurred about 10 million years before and is revealed by similar, though much smaller, impact spherules found at North Pole, 50km west of Marble Bar, and in South Africa,” Dr Hickman said. Originally published on Science Network WA, an independent website based at Scitech. Read more at sciencewa.net.au.