The onset of subduction of the Carnegie Ridge beneath the South American Plate has been dated variously from about mid-Miocene (15 Ma) to about Pleistocene (2 Ma). Although there is agreement that the ridge is being subducted, there is little agreement on the effect that this has had on either the subducting or over-riding plates.
The beginning of the Carnegie Ridge's descent beneath the South American Plate has been dated between roughly 15 million years ago (Miocene) and 2 million years ago (Pleistocene). Although there is agreement that the ridge is being subducted, there is little consensus on how this impacts both the plate it's sinking under and the plate pushing over it.