The East Antarctic craton is an ancient craton

Craton

A craton is an old and stable part of the continental lithosphere. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates. They are characteristically composed of ancient crystalline basement rock, which may be covered by...

 that forms most of Antarctica. The East Antarctic craton was part of the Nena supercontinent

Nena (supercontinent)

Nena was an ancient minor supercontinent that consisted of the cratons of Arctica, Baltica, and East Antarctica. Forming about 1.8 billion years ago, the continent was part of the global supercontinent, Columbia. Nena is an acronym that derives from Northern Europe and North...

 1.8 billion years ago.

During the early Paleozoic

Paleozoic

The Paleozoic era is the earliest of three geologic eras of the Phanerozoic eon, spanning from roughly...

 Era East Antarctica joined the Gondwana

Gondwana

In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...

 supercontinent

Supercontinent

In geology, a supercontinent is a landmass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia qualifies as a supercontinent today.-History:...

.

Breakup

During the Mesozoic

Mesozoic

The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...

 breakup of Gondwanaland, East Antarctica

East Antarctica

East Antarctica, also called Greater Antarctica, constitutes the majority of the Antarctic continent, lying on the Indian Ocean side of the Transantarctic Mountains...

separated from other major continental areas.

During and following this breakup the tectonic terranes of West Antarctica were added to form the current continent of Antarctica.