Fault displacement profiles in multilayer system: from fault restriction to fault propagation
Résumé
The distribution of displacement along faults is a key parameter in various areas of geology such as earthquake studies, three-dimensional strain restoration, fault growth, and reservoir and seal strata relations in hydrocarbon systems. It is essential therefore to understand how local conditions govern displacement distribution. We analyse dip-parallel displacement profiles of normal faults cutting five alternating limestone and shale layers and we discuss their evolution, from their nucleation to their restriction by lithological interfaces or bed-parallel faults in clays, or to their further propagation through several layers. Local displacement gradients control the shape of displacement profiles and are highly variable over the course of fault history. Accordingly, the Dmax-L relation is nonlinear. Bed-parallel faults prove stronger restrictors than lithological interfaces and the correlation of the local gradient with lithology during restriction and propagation indicates that knowledge of these gradients is required if we are to understand how faults develop in multilayer systems.