It formed a triple junction with the Izanagi and Farallon plates in the Panthalassa Ocean as early as 410 million years ago, during which time the Phoenix plate was subducting under eastern Gondwana.

[2] Subduction ceased east of Australia about 120 million years ago, during which time a transform/transpressional boundary formed.

[6] A major decrease in spreading rate of the Antarctic–Phoenix Ridge and the convergence rate of the Phoenix plate with the Antarctic plate occurred around 52.3 million years ago, followed by subduction of a segment of the Antarctic–Phoenix Ridge between 50 and 43 million years ago.

[7][8] Although active subduction occurred for over 100 million years, it slowed dramatically or stopped entirely about 3.3 million years ago when seafloor spreading on the Antarctic–Phoenix Ridge ceased, leaving a small remnant of the former Phoenix plate incorporated in the Antarctic plate.

[6] This remnant underlies the southwest Drake Passage and is surrounded by the Shackleton fracture zone in the northeast, the Hero fracture zone in the southwest, the South Shetland Trough in the southeast and the extinct Antarctic–Phoenix Ridge in the northwest.