Structural inheritance in amagmatic rift basins: Manifestations and mechanisms for how pre-existing structures influence rift-related faults

Abstract

In the context of rift basin formation, structural inheritance describes the influence of pre-existing structures on new rift-related structures, including faults. Pre-existing structures in the crust or upper mantle can determine where rift basins form. As these basins evolve, pre-existing structures in the rocks underneath the newly formed basin can also interact with the far-field strain or stress field, leading to variations in the orientations and kinematics of individual rift-related faults. Given that continental rifts commonly form in pre-deformed lithosphere, structural inheritance is likely to be the norm, not the exception. As such, structural inheritance has implications for reconstructing the paleotectonic history of rifts, investigating seismic hazards, and understanding the fluid transport and storage capabilities of natural fracture systems in the context of geo-energy and ore deposits.The aim of this review is to provide a framework for recognising the various expressions of structural inheritance and their underlying mechanisms in amagmatic rift basins. We synthesise field and geophysical observations and the results of analogue and numerical models to: (1) demonstrate how different inheritance mechanisms (frictional reactivation vs. local re-orientation of the far-field strain and/or stress) can produce different geometric and kinematic relationships between pre-existing structures and rift-related faults; (2) classify these mechanisms in terms of hard-linked and soft-linked inheritance; and (3) show that different mechanisms can be activated at different depths by the same pre-existing structure. These insights can help us better interpret basement structures under the sedimentary cover of rift basins, which are not often well-imaged in geophysical data, and understand the multi-stage evolution of rift basins worldwide.