Continental fragment

Continental crustal fragments, partially synonymous with microcontinents, are fragments of continents that have been broken off from main continental masses forming distinct islands, often several hundred kilometers from their place of origin. All continents are fragments; the terms "continental fragment" and "microcontinent" are restricted to those smaller than Australia. 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: 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 which islands would be considered microcontinents under such a definition. The Kerguelen Plateau is a large igneous province formed by a volcanic hot spot, but was associated with the breakup of Gondwana, was for a time above water, and is therefore considered to be a microcontinent, though not a continental fragment, whereas other hotspot islands such as Iceland and Hawaii are considered neither microcontinents nor continental fragments. This is not a choice in the classification of all islands: The British Isles, Sri Lanka, Borneo, and Newfoundland for example are within the continental shelves of their adjacent continents, separated from the mainland by inland seas flooding its margins.

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