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The syn-rift architecture of extensional basins records deposition from and interactions between footwall-, hangingwall-, and axially-derived systems. However, the exact controls on their relative contributions and the overall variable depositional architecture, and how their sediment volume varies through time, remains understudied. We undertook a quantitative approach to determine temporal and spatial changes in the contribution of fault-scarp degradation to the syn-rift tectono-stratigraphic development of the Thebe-0 fault system on the Exmouth Plateau (NW Shelf, offshore Australia), using high-quality 3D seismic reflection and boreholes data. The magnitude of footwall erosion was measured in terms of vertical (VE) and headward (HE) erosion by calculating the volume of eroded material along the footwall scarp. A detailed seismic-stratigraphic and facies analysis allowed us to constrain the architectural variability of the hangingwall depositional systems and the types of resulting deposits (i.e., fault-controlled base-ofscarp, settling from suspension, and hangingwall-derived). After addressing the syn-rift tectono-stratigraphic framework, we suggest that periods of significant erosion along the Thebe-0 fault scarp are related to the accumulation of faultcontrolled base-of-scarp deposits characterised by comprising a lower wedge with chaotic to low-continuity reflections. Footwall-derived deposits characterised by an upward decrease in stratigraphic dip are interpreted as related to periods of reduced fault activity and sustained sediment delivery sourced from the footwall scarp and systems beyond it (e.g., antecedent systems). We then analysed the tectono-stratigraphic framework and the volumetric comparison between material eroded from the fault-scarp and accumulated in the basin, aiming to estimate the contribution of fault-scarp degradation to the hangingwall syn-rift fill. Our results suggest periods of enhanced fault activity control fault-scarp degradation variability through time, and we agree with that described by previous researchers--fault throw variability along-strike regulates the variability in the magnitude of erosion. However, we propose that fault-scarp degradation timing and its spatial variability are also influenced by the interaction and linkage with adjacent normal faults and by sea level variations. Lastly, we determine broader similarities and differences with a system located in the same fault array (i.e., Thebe-2 fault system), aiming to give insights into the tectono-stratigraphic evolution of a broader area and the spatial variability in fault-scarp degradation. [ABSTRACT FROM AUTHOR]

Gravitational collapse of delta systems is thin-skinned deformation due to sedimentary loading that induces spreading or sliding above a very weak detachment layer and typically consists of up-dip listric extensional faults linked to down-dip a compressional system of toe-thrusts. Detailed mapping and analysis of a modern high-quality, 3D depth-migrated seismic data set from the offshore Ceduna sub-basin, southern Australian margin has shown that gravitational collapse in this sub-basin occurred by multiple failure episodes. We show that the late Albian – early Turonian succession consists of two stacked collapse features; a previously unrecognised Albian–early Cenomanian system 1 and the overlying system 2 of the Cenomanian–early Turonian White Pointer delta of the Ceduna sub-basin. Collapse system 1 is located beneath the extensional domain of the Cenomanian – early Turonian White Pointer collapse system 2, which itself consists of three structural sub-domains that are classified based on fault architectures and geometries, and are named after their relative location as proximal, central, and distal sub-domain. Individual sub-domain consists of scoop-shaped listric normal faults linked downwards to thrust faults. The main faults of these sub-domains detach on multiple decollement surfaces of shales, presumably overpressured. This study proposes an investigation into the development of stacked and complex basinwards sequential formation of gravity collapse features in delta systems on passive margins. The research documents the complex structural styles and evolution of the late Albian – early Turonian stacked delta collapse systems and proposes a revised structural and stratigraphic framework of the Ceduna sub-basin. A four-dimensional (4D) tectonostratigraphic models for the evolution of the late Albian – early Turonian succession within the Ceduna sub-basin is also proposed. • Gravity-driven deformation could potentially consist of few stacked collapse sets. • The late Albian-Turonian gravitational collapse in the Ceduna sub-basin occurred by multiple failure episodes. • Identified two stacked collapse systems - Albian–early Cenomanian system 1 and Cenomanian–early Turonian system 2. • Three deformation sub-domains characterised by scoop-shaped listric faults linked to thrust faults are presented. • The combination of stacked and progressively basinwards developed gravity collapse sets formed complex structural styles. [ABSTRACT FROM AUTHOR]