Continental fragment
Encyclopedia
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. 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
,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, 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
).
Continental fragments
(pieces of Pangea smaller than Sahul
)
Other microcontinents
Australia (continent)
Australia is the world's smallest continent, comprising the mainland of Australia and proximate islands including Tasmania, New Guinea, the Aru Islands and Raja Ampat Islands...
(Australia-New Guinea). Other than perhaps Zealandia
Zealandia (continent)
Zealandia , also known as Tasmantis or the New Zealand continent, is a nearly submerged continental fragment that sank after breaking away from Australia 60–85 million years ago, having separated from Antarctica between 85 and 130 million years ago...
, they are not known to contain a 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...
or fragment of a craton.
Some microcontinents are fragments of Gondwanaland or other ancient cratonic continents: Zealandia, which includes New Zealand
Geography of New Zealand
The geography of New Zealand encompasses two main islands and a number of smaller islands, located near the centre of the water hemisphere. New Zealand varies in climate, from cold and wet to dry and to subtropical in some areas...
and New Caledonia
Geography of New Caledonia
The geography of New Caledonia , an overseas collectivity of France located in the subregion of Melanesia, makes the continental island group unique in the southwest Pacific. Among other things, the island chain has played a role in preserving unique biological lineages from the Mesozoic...
; Madagascar
Geography of Madagascar
Madagascar is an island in the Indian Ocean off the eastern coast of southern Africa, east of Mozambique. It is the fourth largest island in the world. The highest point is Maromokotro, in the Tsaratanana Massif region in the north of the island, at . The capital Antananarivo is in the Hauts...
; the northern Mascarene Plateau
Mascarene Plateau
The Mascarene Plateau is an submarine plateau in the Indian Ocean, north and east of Madagascar. The plateau extends approximately 2000 km, from the Seychelles in the north to Réunion in the south. The plateau covers an area of over 115,000 km² of shallow water, with depths ranging from...
, which includes the Seychelles
Seychelles
Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....
; the island of Timor
Timor
Timor is an island at the southern end of Maritime Southeast Asia, north of the Timor Sea. It is divided between the independent state of East Timor, and West Timor, belonging to the Indonesian province of East Nusa Tenggara. The island's surface is 30,777 square kilometres...
,etc. Other islands, such as several in the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
, 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
Kerguelen Plateau
The Kerguelen Plateau is an underwater volcanic large igneous province , also the microcontinent and submerged continent in the southern Indian Ocean. It lies about 3,000 km to the southwest of Australia and is nearly three times the size of Japan...
is a large igneous province
Large igneous province
A Large Igneous Province is an extremely large accumulation of igneous rocks—intrusive, extrusive, or both—in the earth's crust...
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, whereas other hotspot islands such as Iceland
Geography of Iceland
Iceland is a medium-sized island in the North Atlantic ocean. The island is located east of Greenland and immediately south of the Arctic Circle, atop the divergent boundary of the Mid-Atlantic Ridge in the North Atlantic Ocean. It lies about from New York City and from Scotland...
and Hawaii
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...
are considered neither microcontinents nor continental fragments. This is not a choice in the classification of all islands: The British Isles
British Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...
, Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
, Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
, 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
Sumba
Sumba is an island in eastern Indonesia, is one of the Lesser Sunda Islands, and is in the province of East Nusa Tenggara. Sumba has an area of 11,153 km², and the population was officially at 611,422 in 2005...
, Timor
Timor
Timor is an island at the southern end of Maritime Southeast Asia, north of the Timor Sea. It is divided between the independent state of East Timor, and West Timor, belonging to the Indonesian province of East Nusa Tenggara. The island's surface is 30,777 square kilometres...
(Nusa Tenggara), Banggai
Banggai
Banggai Archipelago is a group of islands, which is located at the far eastern end of Central Sulawesi, Indonesia. It makes up a newly established regency after splitting out of Luwuk. It is surrounded by the Banda Sea's Gulf of Tolo , and the Molucca Sea...
-Sulu
Sulu Archipelago
The Sulu Archipelago is a chain of islands in the southwestern Philippines. This archipelago is considered to be part of the Moroland by the local rebel independence movement. This island group forms the northern limit of the Celebes Sea....
Islands (Sulawesi
Sulawesi
Sulawesi is one of the four larger Sunda Islands of Indonesia and is situated between Borneo and the Maluku Islands. In Indonesia, only Sumatra, Borneo, and Papua are larger in territory, and only Java and Sumatra have larger Indonesian populations.- Etymology :The Portuguese were the first to...
), Obi
Obi
Obi may refer to:* Obi , a sash worn with a kimono or with the uniforms used by practitioners of Japanese martial arts* Obi-Wan Kenobi, fictional character from the Star Wars universe...
, southern Bacan
Bacan
Bacan refers to a group of islands in the Maluku Islands of Indonesia and to that group's largest island. The islands are mountainous and forested. The islands lie south of Ternate and west of Halmahera's southernmost arm...
, and the Buru
Buru
Buru is the third largest island within Maluku Islands of Malay Archipelago. It lies between the Banda Sea to the south and Seram Sea to the north, west of Ambon and Seram islands. The island belongs to Maluku province of Indonesia and includes the Buru and South Buru regencies...
-Seram
Seram
Seram is an island in the Maluku province of Indonesia. It is located north of Ambon Island. The chief port/town is Masohi.- Geography and geology :...
-Ambon
Ambon Island
Ambon Island is part of the Maluku Islands of Indonesia. The island has an area of , and is mountainous, well watered, and fertile. Ambon Island consists of 2 territories: The main city and seaport is Ambon , which is also the capital of Maluku province and Maluku Tengah Ambon Island is part of the...
complex (Maluku
Maluku Islands
The Maluku Islands are an archipelago that is part of Indonesia, and part of the larger Maritime Southeast Asia region. Tectonically they are located on the Halmahera Plate within the Molucca Sea Collision Zone...
).
Continental fragments
(pieces of Pangea smaller than Sahul
Australia (continent)
Australia is the world's smallest continent, comprising the mainland of Australia and proximate islands including Tasmania, New Guinea, the Aru Islands and Raja Ampat Islands...
)
- ZealandiaZealandia (continent)Zealandia , also known as Tasmantis or the New Zealand continent, is a nearly submerged continental fragment that sank after breaking away from Australia 60–85 million years ago, having separated from Antarctica between 85 and 130 million years ago...
- MadagascarMadagascarThe Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
- Mascarene PlateauMascarene PlateauThe Mascarene Plateau is an submarine plateau in the Indian Ocean, north and east of Madagascar. The plateau extends approximately 2000 km, from the Seychelles in the north to Réunion in the south. The plateau covers an area of over 115,000 km² of shallow water, with depths ranging from...
- Jan Mayen Microcontinent
- Rockall Plateau
- South Orkney Microcontinent
- East Tasman PlateauEast Tasman PlateauIn the Cretaceous period, the continental breakup of Gondwana started near Tasmania. About a rift entered the east coast of Tasmania from the south and split off the Lord Howe Rise. Sea floor spreading continued to move this continental sliver away to the east from Tasmania and Australia, and...
- Gilbert Seamount
- ?parts of Wallaby Plateau
- possibly SumbaSumbaSumba is an island in eastern Indonesia, is one of the Lesser Sunda Islands, and is in the province of East Nusa Tenggara. Sumba has an area of 11,153 km², and the population was officially at 611,422 in 2005...
, TimorTimorTimor is an island at the southern end of Maritime Southeast Asia, north of the Timor Sea. It is divided between the independent state of East Timor, and West Timor, belonging to the Indonesian province of East Nusa Tenggara. The island's surface is 30,777 square kilometres...
, and other islands of eastern Indonesia; SulawesiSulawesiSulawesi is one of the four larger Sunda Islands of Indonesia and is situated between Borneo and the Maluku Islands. In Indonesia, only Sumatra, Borneo, and Papua are larger in territory, and only Java and Sumatra have larger Indonesian populations.- Etymology :The Portuguese were the first to...
was formed via the subduction of a microcontinent
Other microcontinents
- CubaCubaThe Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
, HispaniolaHispaniolaHispaniola is a major island in the Caribbean, containing the two sovereign states of the Dominican Republic and Haiti. The island is located between the islands of Cuba to the west and Puerto Rico to the east, within the hurricane belt...
, JamaicaJamaicaJamaica is an island nation of the Greater Antilles, in length, up to in width and 10,990 square kilometres in area. It is situated in the Caribbean Sea, about south of Cuba, and west of Hispaniola, the island harbouring the nation-states Haiti and the Dominican Republic...
, and other granitic Caribbean islands - BarbadosBarbadosBarbados is an island country in the Lesser Antilles. It is in length and as much as in width, amounting to . It is situated in the western area of the North Atlantic and 100 kilometres east of the Windward Islands and the Caribbean Sea; therein, it is about east of the islands of Saint...
- Kerguelen PlateauKerguelen PlateauThe Kerguelen Plateau is an underwater volcanic large igneous province , also the microcontinent and submerged continent in the southern Indian Ocean. It lies about 3,000 km to the southwest of Australia and is nearly three times the size of Japan...