South and East African Fracture Zones: a Long Lifespan Since the Breakup of Gondwana

Abstract

Summary Gondwana started to slit up during the Early Jurassic with the separation of Antarctica and Madagascar from Africa, followed by the separation of South America and Africa during the Middle Jurassic. Yet, the structure and overall kinematic evolution of the three major transform fault zones together – the Agulhas, the Davie, and the Limpopo FZ – which control the opening of the major oceanic basins remain poorly studied. The interpretation of an extensive multichannel seismic dataset allows us to provide new constraints on the structure and evolution of these three transform systems. In particular, results show that the Davie and Agulhas transform faults postdate the development of the rift zone-controlling faults whereas the Limpopo margin seems to show an intracontinental transform faulting stage. Moreover, the Davie and Agulhas FZ recorded spectacular inversions during the transform stage whereas transtensional deformation is observed along the Limpopo FZ. This different style of deformation may be explained by two main forcing parameters: (i) the far-field forces that may induce a rapid change of regional tectonic stress, and (ii) the magmatic conditions that may modify the rheology of the crust. In post-drift history, rapid changes in regional tectonic stress are recorded along the Davie system.