Tectonic geomorphology of Australia

Abstract

Abstract The Australian continent is actively deforming in response to far-field stresses generated by plate boundary interactions and buoyancy forces associated with mantle dynamics. On the largest scale (several 10 3 km), the submergence of the northern continental shelf is driven by dynamic topography caused by mantle downwelling along the Indo-Pacific subduction system and accentuated by a regionally elevated geoid. The emergence of the southern shelf is attributed to the progressive movement of Australia away from a dynamic topography low. On the intermediate scale (several 10 2 km), low-amplitude ( c . 100–200 m) long-wavelength ( c . 100–300 km) topographic undulations are driven by (1) anomalous, smaller-scale upper mantle convection, and/or (2) lithospheric-scale buckling associated with plate boundary tectonic forcing. On the smallest scale (10 1 km), fault-related deformation driven by partitioning of far-field stresses has modified surface topography at rates of up to c . 170 m Ma −1 , generated more than 30–50% of the contemporary topographic relief between some of Australia's highlands and adjacent piedmonts, and exerted a first-order control on long-term (10 4 –10 6 a) bedrock erosion. Although Australia is often regarded as tectonically and geomorphologically quiescent, Neogene to Recent tectonically induced landscape evolution has occurred across the continent, with geomorphological expressions ranging from mild to dramatic.