| Phoenix plate | |
|---|---|
 The Panthalassa Ocean 250 million years ago, showing the Phoenix plate in the south, the Farallon plate in the northeast and the Izanagi plate in the northwest | |
| Type | Historical |
ThePhoenix plate (also known as theAluk plate orDrake plate) was atectonic plate that existed during the earlyPaleozoic through lateCenozoic time. It formed atriple junction with theIzanagi andFarallon plates in thePanthalassa Ocean as early as 410 million years ago, during which time the Phoenix plate wassubducting under easternGondwana.[1]
By the late Jurassic–early Cretaceous, 150–130 million years ago, thePacific plate arose from the Izanagi–Farallon–Phoenix triple junction, resulting in the creation of the Izanagi–Pacific–Phoenix and Farallon–Pacific–Phoenix triple junctions.[2] Subduction ceased east ofAustralia about 120 million years ago, during which time a transform/transpressional boundary formed.[3] This transform/transpressional boundary with the Phoenix plate lasted until about 80 million years ago as the plate continued to descend southwards as a result ofLate Cretaceous subduction under theAntarctic Peninsula.[3][4]
During the Late Cretaceous or early Cenozoic, the southwestern part of the Phoenix plate fragmented into theCharcot plate, much in the same way in which theRivera andCocos plates were formed by the fragmentation of the Farallon plate.[5]
TheAntarctic–Phoenix Ridge, amid-oceanic ridge between the Antarctic and Phoenix plates, initiated following Late Cretaceous to early Cenozoic times when the Phoenix plate haddivergent boundaries with theBellingshausen and Pacific plates in the southwesternPacific Ocean.[6] A major decrease in spreading rate of the Antarctic–Phoenix Ridge and theconvergence 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 whenseafloor 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 southwestDrake Passage and is surrounded by theShackleton fracture zone in the northeast, theHero fracture zone in the southwest, theSouth Shetland Trough in the southeast and the extinct Antarctic–Phoenix Ridge in the northwest.[6][9]
60°18′57″S62°48′23″W / 60.31583°S 62.80639°W /-60.31583; -62.80639
