| Summary: | Abstract Plate kinematic models propose that India and Sri Lanka (INDSRI) separated from Antarctica by extremely slow seafloor spreading that started in early Cretaceous times, and that a long-distance ridge jump left a continental fragment stranded off the Antarctic margin under the Southern Kerguelen Plateau 1-3. Here, we present newly acquired magnetic and deep wide-angle seismic data that require a fundamental re-evaluation of these concepts. The new data clearly define the onset of oceanic crust in the Enderby Basin and off southern Sri Lanka, and date its formation with unprecedented confidence. The revised timing indicates that India and Sri Lanka detached from Antarctica earlier in the east than in the west. Furthermore, no compelling evidence for an extinct spreading axis is found in the Enderby Basin. A refined plate motion model indicates that India and Sri Lanka departed from Antarctica without major rift jumps, but by the action of three spreading ridges with different timings and velocities that must have been accommodated by significant intracontinental deformation.
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