Oblique reactivation of inherited fabrics in rift basins: applications to the Northern Carnarvon Basin

Abstract

Rift basins are typically developed on heterogeneous continental crust. Inherited basement fabrics exert a fundamental control rift basin geometry, and on the geometry of individual faults. Many rift basins are also the result of multiple rift episodes and early formed structures will exert further control on the way in which faults evolve in subsequent rift events. Inherited fabrics and fault reactivation are often invoked to explain rift orientation and segmentation, often with little independent evidence for their existence. However analogue models of orthogonal and oblique rifts show that predictable fault patterns result from the partitioning of stress between pre-existing structures and superimposed extension directions. The Northern Carnarvon Basin provides an ideal laboratory in which to test these models. High resolution 3D seismic data allows detailed imaging of fault patterns developed during separate Lower-Middle Jurassic and Lower Cretaceous rift events. Fault patterns clearly reveal the influence of older structures, most likely related to Carboniferous and Permian rifting, enabling contemporaneous stress patterns to be revealed.