Phoenix Plate

The Phoenix Plate (also known as the Aluk or Drake Plate) was an ancient tectonic plate that existed during the mid-Cretaceous through early Cenozoic time. The remainder of the plate is now located east of the Drake Passage/Shackleton Fracture Zone.

The Phoenix Plate began subducting under the Antarctic Plate. The Phoenix Ridge, a mid-oceanic ridge between the Pacific and the Phoenix Plates which had a spreading rate of 18–20 cm per year until around 84 Ma. A major decrease in spreading rate, and the convergence rate with the Antarctic Plate occurred around 52.3 Ma. During the Late Cretaceous, the Phoenix Plate fragmented into the Charcot Plate, much in the same way in which the Rivera and the Cocos Plate were formed by the fragmentation of the Farallon Plate.

The Antarctic-Phoenix Ridge (sometimes also called the Phoenix Ridge) consists of three extinct spreading ridge segments between the Antarctic Peninsula and the Scotia Sea. This ridge was initiated during the Late Cretaceous-Early Tertiary when the plate had divergent boundaries with the Bellingshausen and Pacific Plates. Bellingshausen was fused with the Antarctic Plate around 61 Ma and the Phoenix plate was gradually subducted by the Antarctic Plate as the Pacific-Antarctic Ridge propagated. The last collision between ridge crest segments and the subduction zone happened around 6.5 Ma and spreading had ceased entirely by 3.3 Ma when the small remnant of the Phoenix Plate was incorporated into the Antarctic Plate. The South Shetland Trench is the south-eastern boundary of the remnant and the Shackleton Fracture Zone is its north-eastern boundary.