Schematic Transform Kinematics of the Australian Precambrian: An Example of Precambrian Intraplate Tectonics

Abstract

The development of Precambrian mobile belts has been interpreted as a result of plate tectonic mechanisms. Recently debates on the role of plate tectonics in the Precambrian have been aired, and many current views tend to test alternative models involving ensialic reactivation or in situ, intraplate, tectonic processes. An attempt to analyze the palaeotectonic distribution, and progressive development, of Australian Precambrian mobile belts invokes the role of transform-like kinematic processes. The transform, ductile shear nature of these ensialic belts explains the internal deformation and the presence of igneous-metamorphic complexes. Contemporaneous, orthogonal zones of limited divergence and convergence are accommodated by this kinematic model. The history of the Australian Precambrian can be defined on the bases of at least five kinematic stages from the Archaean to the late Proterozoic. Each stage is defined by a Eulerian pole of rotation about which small circle arcs are fitted to chronologically appropriate mobile belt curvature traces. Estimates of displacement along the Albany-Fraser mobile belt, of about 600 km, accomodate orthogonal divergent-convergent tectonic zones in Central and Northern Australia.