The extraordinary landscape of Nullarbor Plain in South Australia once harbored a vast prehistoric ocean. It is now a scrub desert on very flat and almost featureless limestone rock for more than a thousand kilometers. However, a new discovery suggests that the vast, semi-arid expanse may not be as featureless as science previously thought.
Its width is about 1300 meters
Using satellite imagery, an international team of scientists led by Matej Lebar, a geologist from the Slovenian Academy of Sciences and Arts, has found an ancient landform that could once have been a coral reef or part of it.
Although science knows that calcium carbonate from shells and fossils can form limestone, experts were surprised by the results.
Nullarbor Plain limestone is rich in coral fossils and algae, but there are no essential features associated with carbonate deposition.
The reef-like landform consists of a raised circular ring about 1,300 m wide with a dome in the middle; It may be the first primary sedimentary structure ever discovered on a plain.Unlike the rest of the world, vast areas of the Nullarbor Plain have remained unchanged through millions of years of weathering and erosion. This is how the unique geological painting of ancient history became.
Through high-resolution satellite images and field work, we have identified clear remnants of the original seafloor structure that has been preserved over millions of years. . said Milo Parham, a geologist at Curtin University in Australia ScienceAlert Online scientific portal. This is the first landform of its kind to be discovered on the Nullarbor Plain.
He added that the ring-shaped “mound” cannot be explained by a meteorite impact or any known deformation process, but preserves the original microbial textures and features typically found in modern Great Barrier Reefs.
Records geological processes dating back to the Miocene
Much of Australia is now saturated with vast and dry inland deserts. But millions of years ago, during the Miocene, the continent was teeming with life; It was covered not only by dense and thriving forest ecosystems, but also by vast inland seas.
The Earth’s surface and terrain operations According to a study published in a scientific journal
The ocean that engulfed the Nullarbor Desert began drying out about 14 million years ago, exposing the shallow water limestone deposited during the Middle Neolithic.
From a geological point of view, few events have occurred on the plain since then: there has been no significant deposition of sediments, but no processes that would lead to the formation of mountain ranges or the occurrence of other features either. This means that Nullarbor is a “clean record” of geological processes and features dating back to the Miocene.
Evidence of long-vanished river channels and dune systems that were pressed directly into the limestone preserves archives of ancient landscapes and even records of prevailing winds. Barham pointed out. “And it’s not just landscapes, because the isolated caves that surround the plains preserve the mummified remains of Tasmanian tigers and the complete skeletons of long-extinct wonders like Thylacoleo, the marsupial lion.”
And that’s not all: due to relatively stable conditions, the surface of Nullarbor Plain has preserved a large amount of meteorites.
Analysis of some limestone rocks on a reef-like structure revealed benthic fossils, unicellular marine organisms, compatible with Nullarbor limestone. However, in one of the samples, the scientists found something interesting: a microbial bond material that could have been formed by corals or algae. Its presence indicates that the reef-like structure originates from the time of limestone deposition.