Structural evolution of a gravitationally detached normal fault array: analysis of 3D seismic data from the Ceduna Sub‐Basin, Great Australian Bight

• Published in: Basin Research
• Main Authors: Robson, A., King, R., Holford, S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2017
• Subjects: Antarc*; Antarctica
• Online Access: http://hdl.handle.net/2440/110263; https://doi.org/10.1111/bre.12191

The growth, interaction and controls on normal fault systems developed within stacked delta systems at extensional delta-top settings have not been extensively examined. We aim to analyse the kinematic, spatial and temporal growth of a Cretaceous aged, thin-skinned, listric fault system in order to further the understanding of how gravity-driven fault segments and fault systems develop and interact at an extensional delta-top setting. Furthermore, we aim to explore the influence of a pre-existing structural framework on the development of gravity-driven normal faults through the examination of two overlapping, spatially and temporally distinct delta systems. To do this, we use three-dimensional (3D) seismic reflection data from the central Ceduna Sub-basin, offshore southern Australia. The seismic reflection data images a Cenomanian-Santonian fault system, and a post- Santonian fault system, which are dip-linked through an intervening Turonian-early Campanian section. Both of these fault systems contain four hard-linked strike assemblages oriented NW–SE (127–307), each composed of 13 major fault segments. The Cenomanian-Santonian fault system detaches at the base of a shale interval of late Albian age, and is characterised by kilometre-scale growth faults in the Cenomanian-Sanontian interval. The post-Santonian fault system nucleated in vertical isolation from the Cenomanian-Santonian fault system. This is evident through displacement minima observed at Turonian-early Campanian levels, which is indicative of vertical segmentation and eventual hard dip-linkage. Our analysis constrains fault growth into four major evolutionary stages: (1) early Cenomanian nucleation and growth of fault segments, resulting from gravitational instability, and with faults detaching on the lower Albian interval; (2) Santonian cessation of growth for the majority of faults; (3) erosional truncation of fault upper tips coincident with the continental breakup of Australia and Antarctica (ca. 83 Ma); (4) Campanian-Maastrichtian ...