From Australian pink sand beaches to undiscovered Antarctic mountain belt
A team of Australian scientists has established a link between the pink beaches of southern Australia and the Great White Continent, and in the process has discovered a previously undiscovered Antarctic mountain belt.
There are many pink sand beaches around the world, but those of the Cape Jervis Formation in southern Australia were of particular interest to scientists. A research team from the University of Adelaide has looked into the matter, and their findings, published in the journal Nature Communications Earth and Environment on June 11, are surprising to say the least.
To possess this color, the sand contains garnet, a mineral whose color varies from red to black, and which has two sources in Australia. The first source comes from the formation of the Adelaide Fold Belt, a geological phenomenon that occurred between 514 and 490 million years ago. A second source comes from the formation of the Gawler craton 3.3 to 1.4 billion years ago. Laser dating has determined that garnet from the beaches of South Australia is 590 million years old. In other words, the mineral was either too old or too young to have formed locally.
Its origins lie elsewhere. In the truest sense of the word. Knowing that garnet is destroyed by prolonged exposure to a marine environment, scientists set out to find a possible source not too far away. So they turned to Antarctica, a continent whose geological history is compatible with the mineral’s formation process. “Garnet requires high temperatures to form and is usually associated with the formation of large mountain belts, and this was a time when the South Australian crust was comparatively cool and non-mountainous.”, mentions Sharmaine Verhaert, PhD student in geology and lead author of the study in a press release issued by the University of Adelaide on June 12.
Garnet had already been discovered in the trans-Antarctic mountains of East Antarctica. Hidden beneath the thick ice cap, researchers believe the region is home to a 590-million-year-old mountain belt. At the end of the Paleozoic, when the supercontinent Gondwana linked Antarctica to Australia, garnet-rich glacial sand would have traveled to Australia, carried over long distances by glaciers that also served to protect the garnet from abrasion. “The garnet deposits were then locally stored in glacial sedimentary deposits along the southern Australian margin until erosion liberated them and the waves and tides concentrated them on the South Australian beaches.”, says Dr. Stijn Glorie, assistant professor of geology and co-author of the study.
But the interest of this research does not stop there. By identifying the source of Australian beach garnet, the research team may have uncovered a previously unknown mountain range hidden beneath the ice cap of Victoria Land and the Transantarctic Mountains. A discovery that could redefine the geological history and early formation of the Pacific Ocean.
Mirjana Binggeli, Polar Journal AG
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