Australia: The Land Where Time Began

A biography of the Australian continent 

Arunta Block

This encompasses the area of the Central Australian shield. The rocks of this shield formed more than 1800 my ago. 2 mountain ranges were formed and eroded away again on this block between 1800 Ma and 900 Ma, when the shield was covered by the sea. The sand that was deposited over the rock at this time, 900 Ma, was covered and squeezed and eventually uncovered again, as the Heavitree Quartzite formation. This section of rock forms the orange cliffs of Ellery Bighole, to the south of the Arunta Block. The fossilised ripples of the sand from 900 Ma can be seen in the quartzite cliffs. See Ellery Creek.

According to Bonamici et al.(Source 2) the sheath fold and subsidiary structures formed during a single deformational event that was progressive is indicated by the uniformity of the foliation, lineation and mesoscale fold orientations across Mount Hay and the constant magnitude of the maximum stretch across structural domains. From the scale inferred of the enclosing shear zone (≥8 km thick) from its geometry, and the regional tectonic correlations it has been inferred that the Mt Hay Sheath Fold formed in a subhorizontal, crustal-scale flow zone during the Strangways Orogeny of the Palaeoproterozoic, 1740-1690 Ma.  The deformation record is consistent with fold formation either on one side of a channel or through detachment flow.


  1. Thermal Extent of the Alice Springs Event, Arunta Block, Central Australia
  2. Geology of the Mt Hay Region, Arunta Block, Central Australia
  3. Central Australian Domain

  4. The Building Blocks of a Continent
  5. Tectonic Evolution of Proterozoic Australia

Sources & Further reading

  1. Penny Van Oosterzee, 1993, The Centre - The Natural history of Australia's Desert Regions, Reed Australia.
  2. Anatomy of a 10 km scale sheath fold, Mt Hay ridge, Arunta Region, central Australia: The structural record of deep crustal flow


Author: M. H. Monroe
Last updated  04/01/2015
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