Structure and tectonics of the Agulhas-Falkland fracture zone

Z. Ben-Avraham, C. J.H. Hartnady, K. A. Kitchin

Research output: Contribution to journalArticlepeer-review

Abstract

The ∼1200-km-long Agulhas-Falkland Transform developed during the Early Cretaceous break-up of West Gondwanaland. On the African Plate, the continent bordering the Agulhas Fracture Zone extends between the Agulhas Bank and the South Tugela reentrant. It is divided into four distinct parts: Mallory Trough segment (I), Diaz Ridge segment (II), East London segment (III) and Durban segment (IV), from southwest to northeast. Each segment differs from the others in its physiography and in the nature of the continent-ocean crustal boundary. In segment I, a wedge-like, eastward-narrowing deep-water basin separates the steep continental slope from a marginal fracture ridge of probable volcanic origin along the transform fault trace. Along segment II the South African continental slope is deeply embayed and a great thickness of sedimentary strata has been ponded behind a buried ridge along the northern side of the fracture-zone trace, above a probable fragment of oceanic crust representing a northerly extension of the Jurassic Falkland Plateau Basin. In segment III, the continental margin is steep, especially along the middle slope; it lies directly along the transform trace, but conspicuously rugged along the continental slope, due to the effects of submarine canyoning and sediment slumping. In segment IV, the continent-ocean boundary also lies directly along the transform fault trace, and the margin shows evidence of seaward tilting above landward-dipping faults along the middle or lower slope. The segmentation is inherited from Jurassic structural fabrics formed prior to Early Cretaceous transform motion, when tectonic rotation of microplates caused rifting and partial oceanization along the future Agulhas-Falkland megafault trajectory.

Original languageEnglish
Pages (from-to)83-98
Number of pages16
JournalTectonophysics
Volume282
Issue number1-4
DOIs
StatePublished - 15 Dec 1997

Keywords

  • Agulhas-Falkland fracture zone
  • Microplates
  • Sheared margin
  • Transform

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