Antarctic Plate
The Antarctic Plate started to subduct beneath South America 14 million years ago in the Miocene epoch. At first it subducted only in the southernmost tip of Patagonia, meaning that the Chile Triple Junction lay near the Strait of Magellan. As the southern part of the Nazca Plate and the Chile Rise became consumed by subduction the more northerly regions of the Antarctic Plate began to subduct beneath Patagonia so that the Chile Triple Junction lies at present in front of Taitao Peninsula at 46°15' S.