Australia: The Land Where Time Began

A biography of the Australian continent 

About 600 Ma the bonding of continents on the opposite side of Antarctica to Australia jolted the Australian continent with such force, in what has been called the Petermann Event, that the Petermann Mountains (See Neoproterozoic Australia) were thrust up thousands of metres along the weak point of thinner crust beneath the old inland sea, somewhere near the border between South Australia and the Northern Territory. By the end of the Petermann Event (The Petermann Ranges Orogeny) the Petermann Mountains were a chain of snow-capped peaks extending for 2000 km. The relatively rapid uplift of vast amounts of rock to form a range, with dimensions like those of the Himalayas, resulted in large amounts of eroded material being deposited in vast alluvial fans, on the northern flank of the mountain range these sediments were eventually buried and consolidated, and after the later erosion of the softer material above and around the harder consolidated rock, Uluru and Kata Tjuta were left exposed.

The present-day Petermann Ranges are a mere shadow of their former glory, being more like a chain of hills than mighty mountains. Uluru (Ayre's Rock) was believed to be consolidated outwash resulting from the erosion of the mighty Peteremanns. Later research has shown that the source of the material from which Uluru formed was carried by palaeorivers from the south.  KatajutaKatajuta (The Olgas) were thought to have originated from the same deposits but are now known to have formed from a different source.

The Petermann Orogeny of the Late Neoproterozoic is believed to be the main influence on the crustal architecture of the present, having overprinted the Musgravian Orogeny of the Grenville that dates to about 1320-1150 Ma (Camacho & McDougall, 2000). A east-trending network of dextral transpressional shear zones, on a crustal scale, were formed by this orogeny, accommodating the rapid burial and exhumation of the Musgrave Province (Camacho & McDougall, 2000). The reorientation of the structural grain of the Grenville within 10-30 km of these shear zones was caused by the focusing of deformation on discrete crustal boundaries (Aitken & Betts, 2008).

Sources & Further reading

1. Penny Van Oosterzee, The Centre - The Natural history of Australia's Desert Regions, Reed Australia, 1993
2. Mary E White, After the Greening, The Browning of Australia, Kangaroo Press, 1994
3. High-resolution aeromagnetic data over central Australia assist Grenville-era (1300-1100 Ma) Rodinia reconstructions

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