Australia: The Land Where Time Began

A biography of the Australian continent 

The Delamerian Orogeny occurred possibly between about 514 million years ago and 500 million years ago, beginning near the end of the Cambrian and continuing into the Ordovician. The Flinders Ranges and the Mt Lofty Ranges are highly eroded remains of the large mountain range that resulted from the folding and faulting that occurred as the sedimentary deposits of the Adelaide geosyncline buckled. There were also a number of volcanic intrusions, such as the granites of Victor Harbour, and in the eastern Mt Lofty Ranges.

Some parts of the Adelaide Geosyncline were not affected by the orogeny. In the northwest, the Stuart Shelf was not affected and in the north and northeast, in the Cooper Basin and the Pedirka Basin limestones and shales were deposited. 

The zone of uplift and folding extended north through Adelaide, the seas over parts of the continent and the Gulf of Carpentaria retreating as the crust was uplifted and folded.

The Delamerian Orogeny continued into the Ordovician, a zone extending from western Tasmania to the north-northwest across western Victoria to north-central South Australia. A climate of high rainfall is indicated by the rapid rate of erosion of this raised crust.

The onset of uplift of the Delamerian Orogeny is marked by the Pantapinna Formation, dated to 515 Ma

Links

1. Atlas South Australia Geology
2. Granite Production in the Delamerian Orogen, South Australia
3. Extensionof the Delamerian (Ross) Orogen into western New Zealand: Evidence from zircon ages and implications for crustal growth along the Pacific Margin of Gondwana.

Sources & Further reading

1. Mary E. White, The Nature of Hidden Worlds, Reed, 1993
2. Veevers, J.J. (ed.), 2000, Billion-year earth history of Australia and neighbours in Gondwanaland, GEMOC Press Sydney

Geology