Abstract - Fault size (e.g. maximum throw and length) and spacing populations from diverse tectonic settings predominantly define power-law distributions. Kinematic analysis of numerical and analogue models and a handful of natural datasets suggests, however, that the size population of active faults becomes non-power-law at higher strains. The breakdown of power-law scaling relationships is often attributed to the increased influence of the thickness of an effective mechanical layer. To test this hypothesis we have analysed the size and spatial characteristics of faults within two layer-bound fault systems imaged on high quality 3D seismic. The examples are from (a) a polygonal intra-formational fault network, South Australia, and (b) a parallel system of intra-formational faults contained within a Tertiary sedimentary succession, NW Porcupine Basin. Fault size and spacing distributions from these fault systems follow exponential to log-normal distributions, with the thickness of the layer-bound systems exercising a critical control on fault system evolution. Power-law scaling properties may have prevailed at the very early stages of fault system evolution but these are entirely obscured by the subsequent non-power-law scaling properties and scale-bound nature of these fault systems.
Abstract of talk given to:
Irish Geological Research Meeting, Dublin, February 2002