Controls on gravity-driven normal fault geometry and growth in stacked deltaic settings: a case study from the Ceduna Sub-basin

Abstract

Kinematics of gravity-driven normal faults exerts a critical control on petroleum systems in deltaic settings but to date has not been extensively examined. The Ceduna Sub-basin (CSB) is a passive margin basin containing the White Pointer (Albian-Cenomanian) and Hammerhead (Campanian-Maastrichtian) delta systems that detach on shale layers of Albian-Cenomanian and Turonian-Coniacian ages, respectively. Here we present evidence for spatially variable fault growth styles based on interpretation of the Ceduna 3D seismic survey and fault kinematic analyses using displacement–distance, displacement–depth and expansion index methods. We identified faults that continuously grew either between the Cenomanian–Santonian or Santonian and the Maastrichtian located throughout the study area and faults that exhibit growth between the Cenomanian–Maastrichtian that are geographically separated into three areas according to their evolution histories: (i) Northern CSB faults exhibit constant growth between the Cenomanian and Maastrichtian. (ii) Central CSB faults show two dip-linkage intervals between (a) Cenomanian and Coniacian–Late Santonian, (b) Coniacian–Late Santonian and Late Santonian–Maastrichtian segments, respectively. (iii) Central and southern CSB faults exhibit dip-linkage intervals between Cenomanian–early Santonian and Late Santonian–Maastrichtian segments. Our study demonstrates a relationship between the location of the Cenomanian–Maastrichtian faults and their evolution history suggesting constant growth evolution at north and dip linkage at the central and south areas.