Continental crustal fragments, partially synonymous with microcontinents, are fragments of continents that have broken off from main continental masses to form distinct islands, often several hundred kilometers from their place of origin. All continents are fragments; the terms "continental fragment" and "microcontinent" are usually restricted] to those smaller than Australia, taking Australia conventionally as the smallest continent. They are not known to contain a craton or fragment of a craton. Continental fragments include some seamounts and underwater plateaus.
Some microcontinents are fragments of Gondwana or other ancient cratonic continents: these include Madagascar; the northern Mascarene Plateau, which includes the Seychelles; the island of Timor, etc. Other islands, such as several in the Caribbean Sea, are composed largely of granitic rock as well, but all continents contain both granitic and basaltic crust, and there is no clear dividing line between islands and microcontinents under such a definition. The Kerguelen Plateau is a large igneous province formed by a volcanic hot spot; however, it was associated with the breakup of Gondwana and was for a time above water, so it is considered a microcontinent, though not a continental fragment. Other hotspot islands such as Iceland and Hawaii are considered neither microcontinents nor continental fragments. Not all islands can be considered microcontinents: the British Isles, Sri Lanka, Borneo, and Newfoundland, for example, are each within the continental shelf of an adjacent continent, separated from the mainland by inland seas flooding its margins.
Several islands in the eastern Indonesian archipelago are considered continental fragments, although this designation is controversial. These include Sumba, Timor (Nusa Tenggara), Banggai-Sulu Islands (Sulawesi), Obi, southern Bacan, and the Buru-Seram-Ambon complex (Maluku).
- Continental fragments (pieces of Pangaea smaller than Australia)
- Other microcontinents (formed post-Pangaea)