'Supermountain' explains Earth's animal evolution

23 October 2006

A text version of the Gondwanan supermountain diagram is also available

Australian scientists have discovered evidence of an ancient 8000-kilometre-long supermountain range that may explain the beginnings of animal life on Earth.

Lead researcher Dr Rick Squire, from Monash's School of Geosciences, estimates that the range of peaks as high as the Himalayas developed between 650 and 500 million years ago during a dynamic period in Earth's history when several large continents collided with each other to form the supercontinent Gondwana.

The Gondwanan supermountain straddled the prehistoric landmass that eventually broke apart into the continents of Australia, New Zealand, Antarctica, South America, Africa, India and Arabia.

Dr Squire said the erosion of the supermountain resulted in enormous volumes of sand, silt and mud washing down a series of huge rivers and being deposited in oceans at the margins of the supercontinent.

"The huge rivers draining the supermountain provided a dramatic flux in nutrients, which supported a bloom of primitive life, and that provided the huge source of food necessary to trigger the sudden appearance of animals on Earth between about 580 and 520 million years ago," Dr Squire said.

Dr Squire and his team collected sandstone samples from around Victoria, including the Stawell gold mine, that contained many different minerals including zircon, which can be dated using a spectrometer.

"Remarkably, the ages of the zircons in the different samples were all very similar and closely matched results from other sandstone samples collected from other continents that once formed Gondwana," he said. "The similarities in age suggest a similar source, and the most likely candidate was the supermountain.

"The sandstones can be found everywhere in Australia, from Kalbarri on the western tip of Western Australia to the large rocky road cuttings north of Sydney near the Hawkesbury River. The Victorian Parliament building is made from Grampians Sandstone that was originally sourced from the supermountain, and the big gold deposits at Bendigo, Ballarat and Stawell all formed in sandstones that came from the same geological phenomenon," he said. 

Dr Squire's findings are published in the latest issue of the journal Earth and Planetary Science Letters.

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