Australia: The Land Where Time Began

A biography of the Australian continent 

North and West of the Gawler Craton

There are several planation surfaces and palaeodrainage channels that have siliceous fills that have been recognised in the Officer Basin to the north and west of the Gawler Craton. The silicification has been attributed to either the earlier or later Tertiary by various authors (Wopfner, 1967; Benbow et al., 1995a; 1995b; McNally & Wilson, 1995; Hon et al., 2003). In the Eromanga Basin silcrete plateaux are also prominent. To the southwest of Lake Eyre the plains have a duricrust of silcrete from the Pleistocene, and have an opaline matrix, in contrast to the microcrystalline structure seen in older siliceous duricrusts (Wopfner & Twidale, 1967).

The strata to the west of the Basin, from the Upper Jurassic and Cretaceous, thin out and disappear to the southwest of the Basin. There is a plane that is eroded in various Proterozoic and Palaeozoic rocks that has long been identified as an exhumed sub-Cretaceous, (Late Jurassic) surface (Jack, 1931; Wopfner, 1964). The Peake and Denison (or Davenport) Ranges are isolated remnants of the Adelaide Geosyncline fold belt (Flint, 1993), that are upfaulted on their eastern side and the prominent summit surface is suggested by the author1 to likely be an uplifted part of the sub Late Jurassic surface that is so prominent at the southwestern margin of the Eromanga Basin (Jack, 1931; Wopfner, 1968).

To the west of the Gawler Craton, the Eucla Basin, that has exposures of limestones from the Eocene and Miocene in the coastal cliffs, is occupied by the Nullarbor Plain, a plain that is featureless, that is best interpreted as an etch plain from the Pliocene or Pleistocene (Lowry, 1970; Lowry & Jennings, 1974; Twidale, 1990). At the northeastern margin of the plain, the Barton Range and Ooldea Range, are coastal dunes from the ?Miocene that have been preserved by a calcrete capping (Benbow, 1990).

Sources & Further reading

  1. Twidale, C.R., 2007, Ancient Australian Landscapes, Rosenberg Publishing Pty. Ltd. , NSW
Author: M. H. Monroe
Last updated 27/10/2013
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