Australia: The Land Where Time Began |
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Officer Basin The Officer basin was uplifted at the end of the Cretaceous, when it formed its own river system that flowed to the south. This Neoproterozoic to Late Devonian basin covers parts of South Australia and Western Australia. It is 410,000 km2 and a maximum sediment thickness of 10 km. It comprises several major depocentres. After a short, minor period of rifting it subsided by thermal sag. Mostly fluvial and marine siliceous and carbonate sediments and evaporites were deposited in its depocentres. Then followed an erosional surface overlain by fluvial and glacial deposits With the extensive uplift along the northern margin of the basin at the start of the Petermann Ranges Orogeny, and widespread deposition of silicates and carbonates during the latest Proterozoic-Late Cambrian. The start of the Delamerian Orogeny, accompanied by extensive basaltic volcanism in the centre and west of the basin, stopped the Cambrian sedimentation. During the Ordovician a period of extension led to the deposition of shallow marine to fluvial-deltaic silicates in the northeastern part of the basin. This sedimentation stopped in the latest Ordovician or Silurian with the uplift associated with the Alice Springs Orogeny. Also in the northeastern part of the basin, space was made for the deposition of fluvial silicates during the Late Devonian by a suspected extension event. See Neoproterozoic Australia, Central Australian Basins,
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Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |