Plate tectonic development of the south west Indian Ocean: A revised reconstruction of East Antarctica and Africa

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Abstract
A revised sequence of reconstructions for East Antarctica relative to Africa is generated from published seafloor spreading and fracture zone anomalies. These date from the Cretaceous/Tertiary boundary to the Late Jurassic and lead to a revised predrift reconstruction for east and west Gondwanaland: Euler pole 1.67°S, 35.99°E, rotation angle 53.43°. This reconstruction derived wholly from marine data places East Antarctica adjacent to the Lebombo Mountains and south of and subparallel to the Sabi acid volcanic suite, supporting the postulate that these rocks represent Mesozoic plate boundaries. This refit implies that part of the coastal plain of Mozambique is underlain by oceanic or very highly extended continental crust. The reconstruction is supported by the alignment of (1) the Cape Fold Belt with its Antarctic equivalents and (2) the western limit of Pan‐African reactivation of the Mozambique Mobile Belt with the western limit of the Sverdrupfjella metamorphic suite. Antarctica initially moved along a transform fault lying immediately east of and subparallel to the Lebombo Mountains, the eastern face of the Tugela Cone, the southeastern face of the Falkland Plateau in its reconstructed position, and the eastern flank of the Agulhas Plateau in its reconstructed position. At M10 time a triple junction formed near the tip of the Falkland Plateau implying that the oldest lineated magnetic anomalies in the eastern Weddell Sea associated with this triple junction cannot predate M10. At M2 time the Mozambique Ridge rifted from the Astrid Ridge in a ridge jump episode. Such an event may also explain the presence of magnetic anomalies in the southern Mozambique Basin. Gunnerus Ridge, Conrad Rise, and Del Cano Rise are all tectonically associated with the Madagascar Ridge.