On the evening of 20 October Professor Chris Elders of Curtin University presented “The Peculiarities of Australia’s Northern and Western Margins” to a group of 34 souls at the Shoe Bar. The presentation focused on the role of structural inheritance from Palaeozoic rifts on the subsequent Mesozoic rifting. His presentation opened by suggesting that the NW Shelf rift margin, especially the northern Carnarvon Basin, has its own distinctive characteristics of narrow necking domains coupled with a wide proximal domain of thick Mesozoic sequences and thin lower continental crust. The Palaeozoic structural architecture is interpreted to have exerted a significant control on subsequent structural architecture and stratigraphy of the Mesozoic, in particular the accumulation of thick sequences of Triassic sediments in the Northern Carnarvon Basin over a wide proximal domain, and the distribution and geometry of subsequent Jurassic rift episodes. Tectonic reconstructions of the Permian may account for the morphology of the NW margin, from the NW Shelf to the Perth Basin. The presentation raised some interesting questions regarding the evolution of the NW Shelf margin, which are unresolved partly due to the absence is of its conjugate (Argoland) which has now disappeared to the north.
