Abstract

Abrupt regression events in the Devonian of eastern Australia, lacking synchroneity from region to region, contrast with the extensive and well defined inter-regionally synchronous transgression-regression pattern; the latter is fundamentally concordant with the global eustatic pattern recently discriminated for the Devonian. Such abrupt events, typically characterized by dramatic change in style of sedimentation, are taken to be connected with the changing pattern of diastrophism through Devonian time in eastern Australia. There was plurality of such events but whether these, in aggregate, are reflections of episodic or continuous style diastrophism is not yet clear.

The best available data for time constraints on these diastrophic events are set forth and shown to be consistent with a more intricate pattern than generally visualized. For pre-Emsian Bowning and/or Bindi diastrophic pulses (and their associated vulcanism and plutonism) the main focus of activity was in southeastern Australia, as it was for antecedent Silurian diastrophism. For Tabberabberan events (serotinus Zone and younger), the data - though not necessarily constraining as to interpretation - are consistent with maximum intensity in the south with, through time, northward augmentation of the area undergoing orogenesis. This accords with oblique and diachronous plate-interaction. The pattern of plate movements, nevertheless, has yet to be satisfactorily elucidated. The tectonics obviously involved considerable strike-slip fault movement, including large scale (hundreds of kilometres) relative displacement of tectonostratigraphic terranes. This has not been taken into account in recent palinspastic reconstructions.