Continental fragment

Continental fragment

Continental crustal fragments, partially synonymous with microcontinents, are fragments of continents thought to have been broken off from the main continental mass forming distinct islands, possibly several hundred kilometers from their place of origin.[1] All continents are fragments; the terms 'continental fragment' and 'microcontinent' are restricted to those smaller than Sahul (Australia-New Guinea). Other than perhaps Zealandia, they are not known to contain a craton or fragment of a craton.

Some microcontinents are fragments of Gondwanaland or other ancient cratonic continents: Zealandia, which includes New Zealand and New Caledonia; Madagascar; the northern Mascarene Plateau, which includes the Seychelles; the island of Timor,[2]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 boundary as to 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 Gondwanaland, was for a time above water, and is therefore considered to be a microcontinent, though not a continental fragment,[3][4] 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.

Several islands in the eastern Indonesian archipelago are considered continental fragments, although this is a controversial theory. These include Sumba, Timor (Nusa Tenggara), Banggai-Sulu Islands (Sulawesi), Obi, southern Bacan, and the Buru-Seram-Ambon complex (Maluku).[5]

Continental fragments

(pieces of Pangea smaller than Sahul)

  • Zealandia
  • Madagascar
  • Mascarene Plateau
  • Jan Mayen Microcontinent
  • Rockall Plateau
  • South Orkney Microcontinent[6]
  • East Tasman Plateau
  • Gilbert Seamount
  • ?parts of Wallaby Plateau
  • possibly Sumba, Timor, and other islands of eastern Indonesia; Sulawesi was formed via the subduction of a microcontinent
Other microcontinents

References

  1. ^ Monk,, K.A.; Fretes, Y., Reksodiharjo-Lilley, G. (1996). The Ecology of Nusa Tenggara and Maluku. Hong Kong: Periplus Editions Ltd.. p. pages 41–43. ISBN 962-593-076-0. 
  2. ^ Monk,, K.A.; Fretes, Y., Reksodiharjo-Lilley, G. (1996). The Ecology of Nusa Tenggara and Maluku. Hong Kong: Periplus Editions Ltd.. p. pages 27–29. ISBN 962-593-076-0. 
  3. ^ UT Austin scientist plays major rule in study of underwater "micro-continent". Retrieved on 2007-07-03
  4. ^ Sci/Tech 'Lost continent' discovered Retrieved on 2007-07-03
  5. ^ Monk,, K.A.; Fretes, Y., Reksodiharjo-Lilley, G. (1996). The Ecology of Nusa Tenggara and Maluku. Hong Kong: Periplus Editions Ltd.. p. page 41. ISBN 962-593-076-0. 
  6. ^ R. A. J. Trouw; C. W. Passchier, L. S. A. Simőes, R. R. Andreis and C. M. Valeriano (1997). "Mesozoic tectonic evolution of the South Orkney Microcontinent, Scotia arc, Antarctica". Geological Magazine 134: 383–401. doi:10.1017/S0016756897007036. 

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