Geomorphological development of the eastern margin of the Australian Craton

Abstract

The denudation chronologies of five uplands of contrasting geological structure located at the eastern margin of the Australian Craton are examined. They are the Isa Highlands, MacDonnell Ranges and Flinders Ranges (fold mountains, orogenic setting); the Arcoona Plateau (dissected plateau, platform setting); and the Gawler Ranges (massif of old silicic volcanics, cratonic setting). In each, surfaces of Mesozoic age, many of them exhumed and of pre-Cretaceous age, are preserved. Each also appears to have been uplifted recurrently. Each was either overwhelmed or bordered by the Early Cretaceous (Neocomian-Aptian) sea.Tectonism associated with the break-up of Gondwana probably allowed this important marine transgression. Thereafter, thalassostatic and erosional/depositional isostatic responses have maintained the uplands as uplands and the intervening basins as negative topographic and structural units; the pattern of topography has been constant for the last 60-100 Ma.

A study of Lake Wyara, an episodically filled saline lake in southwest Queensland, Australia

“…Lake Wyara lies in a down-faulted area just east of a Tertiary fault (Senior, 1971), but there has been extensive modification of the basin by sedimentation and wind-induced currents. Other large inland saline lakes in Australia are of tectonic origin and have similar basin modifications (Campbell and Twidale, 1993;Dulhunty, 1975Dulhunty, , 1982Dulhunty, , 1990Timms, 1992). The numerous beaches at various levels on the eastern shore have resulted from a dominant westerly wind regime acting over a wide range of water-levels.…”

The biology of the saline lakes of central and eastern inland of Australia: a review with special reference to their biogeographical affinities

“…Lake Torrens lies in a graben with basal lacustrine sediments of Cainozoic age (Twidale & Campbell, 1993), Lake Eyre has been present in some form since the middle Jurassic but its present basin was created by epeirogenic earth movements in the last 30,000 years (Kotwicki, 2000). Lake Wyara lies on a Tertiary fault (Timms, 1998a), and Lake Buchanan lies along a fault line in an intermontane basin and dates back in some form to the early Tertiary (Chivas et al, 1986).…”

“Canons” revisited and reviewed: Lester Kingʼs views of landscape evolution considered 50 years later

“…Such unequal erosion, combined with episodic degradation, has led to the stepped topography found in many areas (King, 1962;Crickmay, 1974). Recurrent epeirogenic uplift of some blocks and subsi-dence of others, due to a combination of crustal stress, isostatic adjustments, and in some areas, thalassostatic loading, enhances such effects (Jessen, 1943;Bourcart, 1950;Twidale and Campbell, 1992).…”

“…There is sound evidence and argument to suggest that inselbergs such as Wudinna Hill in the Eyre Peninsula of South Australia (crest of Cretaceous? age) and Ayers Rock in central Australia (Maastrichtian) have increased in relief amplitude through time, not because of uplift but because of the stability of their crests and concurrent episodic lowering of the surrounding plains (Twidale and Bourne, 1975a;Twidale, 1982aTwidale, , 1978b see also Jessen, 1936;Twidale and Campbell, 1992). Similarly, massifs such as the Gawler Ranges (Neocomian-Aptian) and the Hamersley Ranges (Middle Eocene) now stand higher in the local relief than in the past.…”