Elastic flexure and distributed deformation along Australia’s North West Shelf: Neogene tectonics of the Bonaparte and Browse basins
Published:January 01, 2008
Myra Keep, Mathew Harrowfield, 2008. "Elastic flexure and distributed deformation along Australia’s North West Shelf: Neogene tectonics of the Bonaparte and Browse basins", The Nature and Origin of Compression in Passive Margins, Howard Johnson, Tony G. Doré, Robert W. Gatliff, Robert W. Holdsworth, Erik R. Lundin, J. Derek Ritchie
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Neogene collision between Australia and the Banda Arc modified the adjacent Bonaparte and Browse basins of the North West Shelf of Australia. Modification comprised both continuous long-wavelength amplification of Permo-Carboniferous basement topography and flexure and normal faulting of Triassic–Recent sedimentary cover. Deformation was continuous across the Browse and Bonaparte basins, despite the basins beings separated by a rupture-barrier style accommodation zone, the Browse–Bonaparte Transition. The degree of basement control and mechanisms of fault linkage vary significantly across this transition, and reflect differences in the structural relief, amplitude and depth of rifted basement either side of the transition. Neogene collision amplified the architectural divide. Amplification of basement topography over wavelengths of several hundred kilometres was associated with negligible horizontal length change. The transcurrent component of Neogene deformation was partitioned outboard of any continuous flexural amplification.
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The Nature and Origin of Compression in Passive Margins
Increasingly, researchers have reported that passive margins do not show a simple uninterrupted thermal sag pattern of post-rift subsidence following continental separation. Rather, the structural and stratigraphic development of such margins may record evidence of complex phases of differential subsidence, exhumation and fold development. Some of the fold structures observed on passive continental margins appear to be related to regional stresses transmitted through basement rocks, whereas others are related to gravitational sliding and toe-thrusting. This special publication concentrates on the first of these categories. The morphology and distribution of such folds, together with potential mechanisms for generation of regional stress, are described in a series of papers by authorities in the field. As well as being an enigmatic feature of passive margin geology, the compressive folds have significance in the exploration for petroleum.