How an ancient impact on Australia may have triggered global changes in climate and ocean chemistry
An ancient asteroid struck Australia 600 million years ago, leaving a long, shallow crater. Fracture grooves and rock deformations reveal the force of the impact, but its full impact remains unknown.
About 600 million years ago, Earth was home to strange, soft sea creatures, but a powerful asteroid impact in the northern region of Australia, as we know it today, could have wiped them out.
This impact left a long, shallow groove and sent shock waves through the rock, creating rare geological formations called fracture grooves. Although the full extent of the destruction is not fully understood, geologists believe that other large asteroid impacts from this period could have triggered global changes in climate and ocean chemistry, and may even have played a role in one of the first mass extinctions on Earth.
A strange and ancient world
About 600 million years ago, during the Ediacaran period, the Earth looked very different from today. The land, recently emerging from a global freeze, was almost barren and lifeless. However, the oceans were full of strange, soft creatures. Among them were worm-like organisms with crescent-shaped heads and, on land, tall fern fronds.
Devastating impact on ancient Australia
These ancient creatures may have become extinct when an asteroid, estimated to be between 200 and 400 meters in diameter, swept across the sky and struck land or shallow water near what is now known as the Danwa Ridge. Although the original crater has been largely obliterated over time, evidence of the impact remains etched in sedimentary layers and remnants of volcanic activity in the area.
On February 3, 2025, the Operational Land Imager (OLI) on the Landsat 8 satellite captured an image of the impact site, in an area called the Amelia Creek Structure. The impact left a trench about 1 kilometer wide and 5 kilometers long. Analysis of the satellite observations indicates that the deformation in the regional rock layers extends about 10 kilometers north and south of the trench, with minimal deformation to the east and west.
The elongated, narrow shape of the groove and the pattern of regional deformation indicate that the asteroid struck at a particularly shallow angle. A sharper-angled asteroid impact, such as the one that wiped out the dinosaurs, would have left a deeper, more symmetrical groove and created a raised structure in the center of the groove called a central uplift.
Additional clues to the Amelia Creek impact event are buried in the nearby quartzite rock layers. Beginning in the 80s, geologists discovered fan-shaped cracks that were later identified as fracture grooves—rare geological formations formed when shock waves from impacts travel through rock. All of the fracture grooves in the area are distributed in a moon-like pattern, mostly south of the groove, again indicating that the asteroid struck at a shallow angle.
The mysterious traces of the impact
The amount of damage caused by the impact is unclear, but it is believed that asteroids that strike at shallow angles cause less severe damage than those that strike at sharp angles. The shallow angle means that the rocky body passes through the atmosphere for a longer time, causing it to burn up more mass and sometimes break up into smaller pieces before impact.
While the most severe damage was likely concentrated near the impact site, geologists have gathered evidence that two larger asteroid impacts during the Ediacaran period could have had widespread and even global effects, perhaps contributing to the extinction of a mysterious group of creatures called acritarchs and helping to cause global changes in ocean chemistry and climate.
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I found it 🙂 Acritarchs https://palynology.org/what-is-palynology/palynomorphs/acritarchs They are fossilized exoskeletons of a group of protists (eukaryotic organisms (living cells with a nucleus and organelles) that are not in the animal, fungal, or plant kingdoms, and are considered a kingdom in their own right).
Does anyone know what acritarchs are? Google doesn't know them, so if you can send a source, a link, something, thanks in advance.
An asteroid 200-400 meters in size does not cause a global disaster and certainly does not destroy anything.
What is thought to have wiped out the dinosaurs was about 50 times bigger.