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Interactions between footwall-, hangingwall- and axial-derived depositional systems make syn-rift stratigraphic architecture difficult to predict, and preservation of net-erosional source landscapes is limited. Distinguishing between deposits derived from fault-scarp degradation (consequent systems) and those derived from long-lived catchments beyond the fault crest (antecedent systems) is also challenging but important for hydrocarbon reservoir prospecting. We undertake geometric and volumetric analysis of a fault-scarp degradation complex and adjacent hangingwall-fill associated with an individual fault block in the northern Carnarvon Basin, NW Shelf, Australia. Fault throw, and vertical and headward erosion of the complex are measured. Seismic-stratigraphic and seismic facies analyses allow us to constrain the along-strike architectural variability of the footwall-derived fans in the hangingwall. Footwall-derived systems interacted with hangingwall- and axial-derived systems, through diversion around topography, interfingering, or successive onlap. We calculate the volume of footwall-sourced hangingwall fans for nine quadrants along the fault block, and compare this to the volume of material eroded from the immediately up-dip fault-scarp. This analysis highlights areas of sediment bypass (excess erosion) and areas fed by sediment sources beyond the degraded fault scarp (excess hangingwall-fill). Exposure of the border fault footwall and adjacent fault terraces produced small catchments located beyond the fault crest that fed the hangingwall basin. One source persisted nearly throughout the syn-rift episode, and its location coincided with: (i) an intra-basin topographic high; (ii) a local fault throw minimum, possibly representing a breached relay ramp; (iii) increased vertical and headward erosion within the fault-scarp degradation complex; and (iv) sustained clinoform development in the immediate hangingwall. Our novel quantitative volumetric approach to identify through-going sediment input points and areas dominated by sediment bypass could be applied to other rift basin-fills. We also emphasise the need to incorporate interaction of multiple sediment sources and their resultant architecture in tectono-stratigraphic models for rift basins.

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