South and East African Fracture Zones: a long lifespan since the breakup of Gondwana - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue The Geological Society, London, Special Publications Année : 2022

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

François Sapin
  • Fonction : Auteur
  • PersonId : 1127022
Sylvie Leroy

Résumé

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 magmatic additions that may compensate a part of the displacement and modify the structural style. In the post-drift history, several reactivations of transform fault zone are recorded implying that some transform margins are excellent recorders of large plate kinematic changes. Such reactivations can serve also as drains for magmatic fluids in the vicinity of hotspots emplacement.
Fichier principal
Vignette du fichier
SP524-2022-25.pdf (4.2 Mo) Télécharger le fichier
Origine Fichiers produits par l'(les) auteur(s)
Licence

Dates et versions

hal-03982694 , version 1 (12-10-2023)

Licence

Identifiants

Citer

Vincent Roche, Jean-Claude J-C Ringenbach, François Sapin, Sylvie Leroy. South and East African Fracture Zones: a long lifespan since the breakup of Gondwana. The Geological Society, London, Special Publications, 2022, 524 (1), pp.279 - 305. ⟨10.1144/SP524-2022-25⟩. ⟨hal-03982694⟩
26 Consultations
34 Téléchargements

Altmetric

Partager

Gmail Mastodon Facebook X LinkedIn More