South and East African Fracture Zones: a long lifespan since the breakup of Gondwana

• Published in: Geological Society, London, Special Publications
• Main Authors: Roche, Vincent, Ringenbach, Jean-Claude, J-C, Sapin, François, Leroy, Sylvie
• Other Authors: Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Total E&P, Vincent Roche was supported by a grant from the Passive Margin Exploration Laboratories (PAMELA) project and by funds from Sylvie Leroy and Sorbonne Université. The PAMELA project is a scientific project led by Ifremer and TotalEnergies in collaboration with Université de Bretagne Occidentale, Université Rennes 1, Sorbonne Université, CNRS and IFPEN.
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Antarctic; Antarctic Ocean; Austral; Corridor The; Corridor, The; Weddell; Weddell Sea; Antarc*; Antarctica
• Online Access: https://hal.science/hal-03982694; https://hal.science/hal-03982694/document; https://hal.science/hal-03982694/file/SP524-2022-25.pdf; https://doi.org/10.1144/SP524-2022-25

Gondwana started to split up during the Early Jurassic (ca. 180 Ma) with the separation of Antarctica and Madagascar from Africa/South America, followed by the separation of South America and Africa during the Early Cretaceous. Thanks to recent seismic profiles, the architecture of rifted margins and the transform faults zones, which developed as a result of the relative motion between tectonic plates, have been recently evidenced and studied along the whole eastern and southeastern Africa margins (i.e., in the Western Somali Basin, the Mozambique Basin, the Natal Basin, and the Outeniqua Basin). Yet, the structure and overall kinematic evolution of the three major transform faults zones together - i.e., the Agulhas, the Davie, and the Limpopo Fracture Zones (FZ) - that control the opening of major oceanic basins (Antarctic Ocean, Weddell Sea and Austral South Atlantic) remain poorly studied. The interpretation of an extensive regional multichannel seismic dataset coupled with recent studies allows us to propose a detailed regional synthesis of the crustal domains and major structural elements of the rifted margins along the whole eastern and south-eastern Africa. We provide new constraints on the structure and evolution of these three transform systems. Although our findings indicate common features in transform style (e.g., a right-lateral transform system, a wide sheared corridor), the deformation and magmatism along these systems appear quite different. In particular, our results show that the Davie and Agulhas transforms faults postdate the development of the rift zone-controlling faults whereas the Limpopo margin seems to be a simple intra-continental transform. Moreover, the Davie and Agulhas FZ recorded spectacular inversions during the transform stage whereas transtensional deformation is developed 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 ...