A plate tectonic model of the Palaeozoic tectonic history of New South Wales

Abstract

An updated∗ tectonic model for the Palaeozoic tectonic history of New South Wales, based on actualistic models of plate tectonics, has resulted from tectonic analyses and syntheses during the compilation of the Tectonic Map of New South Wales. Most emphasis is given to marginal seas, which characterize Pacific marginal mobile zones. Marginal seas form in the regime of lithospheric tension under the influence of retrograde motion of the Benioff zone, and during the formation of a new Benioff zone, or during formation of spheno‐ and rhombochasms. Additional mechanisms for obduction zone formation are suggested: the development of an obduction zone at the originally coupled continental margin is important. Three basic types of volcanic chains are distinguished: volcanic arcs, volcanic arches, and volcanic rifts, in the formation of which both primary subduction zones at major plate margins, and secondary subduction zones which develop in marginal seas may be concerned. During the Palaeozoic the eastern part of the Australian continent evolved in a complicated process of continental crust accretion. By interaction of the Australian plate (Proterozoic continent) with the neighbouring oceanic, Palaeo‐Pacific plate, systems of marginal seas, volcanic chains, island arcs, microcontinents, flysch wedges or trench complexes, and primary and secondary Benioff zones were formed, and also deformed, episodically. The most active role during the structural deformation was played by the continental plate moving towards the adjacent primary Benioff zone.