Mesozoic seafloor spreading anomalies MO-M10 have been identified in the Natal Valley between the south-eastern African margin and the Mozambique Ridge. These identifications confirm that seafloor spreading north and south o f the Falkland Agulhas Fracture Zone (FAFZ) began simultaneously. The Natal Valley anomalies are offset -1300km by the FAFZ from their equivalents in the southern Cape Basin. Their positions confirm that the Tugela Ridge marks the continent/ocean boundary (COB) in the Natal Valley. We have computed successive Falkland Plateau palaeopositions using Natal Valley and Georgia Basin anomalies. These show that the offset in spreading ridges at the FAFZ remained -1300km long from M10 to MO time. By anomaly 34 time, the offset was -1270 km. Therefore no major ridge jumps had occurred by then. Dating MO as 108 Myr BP and anomaly 34 as 80 Myr B P , the average halfspreading rate immediately south of the FAFZ for the Cretaceous Normal Polarity Epoch is 4.2 cm yr-' . Using this, we date: (a) the change in early pole of rotation at 105 Myr; (b) a reconstruction which juxtaposes salt boundaries in the Brazil and Angolan basins at 103.7 Myr; (c) final separation of the Falkland Plateau from southern Africa at 98.3 Myr; (d) the formation of the oceanic northern part of the Agulhas Plateau at 97.3-90.7 Myr.Comparison of magnetic data with implied COB positions in the southernmost Cape and Argentine Basins, and the Georgia Basin suggests continental separation began 122-1 27 Myr BP with undeformed magnetic anomalies dating from 122 Myr (M10). These dates are consistent with micropalaeontological and sedimentological data around southern Africa.
Sedimentation over large areas of a marginal plateau, the northernmost Natal Valley (NNV), is influenced by the tropical/sub-tropical Agulhas Current. Through mobilization of detritus and concentration of sedimentation into localized depo-centres, current action provides a mechanism for hiatus development both in on-shelf and off-shelf areas. Post-Gondwana break-up sedimentary basin in-fill is interrupted by several regional hiatuses. These correlate with coastal regressions, global sea-level low-stands, proposed phases of invigorated oceanic circulation and with global phases of slow deep-sea sedimentation. An assessment of these mechanisms indicates detritus supply related to sea-level changes cannot explain correlation of on-shelf and off-shelf hiatuses. Current action may have been a contributory factor in development of a Cenomanian/Turonian hiatus and facies change and a Cretaceous/Tertiary boundary hiatus.
An Early Oligocene hiatus clearly marks a change in the Agulhas Current regime. Current-moulded features, asymmetric sediment distributions and re-working attest to enhanced current action. Establishment of a cold bottom layer in the ocean at this time stimulated Indian Ocean surface/near-surface circulation. New circulation patterns were established after a Miocene/Pliocene boundary hiatus. Since then the main flow-paths have been fairly stable, although local depo-centre shifts late in the Pliocene–Recent sequence suggest eastward movement of a counter-current and cyclonic eddy off Maputo.
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