supercontinent

Information about supercontinent

In geology, a supercontinent is a land mass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia[1] qualifies as a supercontinent today.

History

Most commonly, paleogeographers employ the term supercontinent to refer to a single landmass consisting of all the modern continents. The earliest known supercontinent was Vaalbara. It formed from proto-continents and was a supercontinent by 3.1 billion years ago (3.1 Ga). Vaalbara broke up ~2.8 Ga. The supercontinent Kenorland was formed ~2.7 Ga and then broke sometime after 2.5 Ga into the proto-continent cratons called Laurentia, Baltica, Australia, and Kalahari. The supercontinent Columbia formed and broke up during a period of 1.8 to 1.5 billion years (1.8-1.5 Ga) ago.

The supercontinent Rodinia broke up roughly 750 million years ago. One of the fragments included large parts of the continents now located in the southern hemisphere. Plate tectonics brought the fragments of Rodinia back together in a different configuration during the late Paleozoic era, forming the best-known supercontinent, Pangaea. Pangaea subsequently broke up into the northern and southern supercontinents, Laurasia and Gondwana.

Modern studies have suggested that supercontinents form in cycles, coming together and breaking apart again through plate tectonics, very roughly about every 250 million years.

Geology

Supercontinents block the flow of heat from the Earth's interior, and thus cause the asthenosphere to overheat. Eventually, the lithosphere will begin to dome upward and crack, magma will then rise, and the fragments will be pushed apart. It is currently a matter of some debate as to how the supercontinents reform, whether or not plate tectonics makes them re-join after travelling around the planet, or if they move apart and then back together again.

In other areas of study such as history and geography, land masses connected with an isthmus are also considered supercontinents or just continents, such as the Americas. Some historians call the combined land mass of Africa and Eurasia the supercontinent Africa-Eurasia.

Incomplete list of minor past supercontinents

These are supercontinents that comprised only a fraction of the land on Earth.

Incomplete list of supercontinents

Main article: List of supercontinents
In reverse-chronological order (stratolithic order) comprising nearly all land at the time.
  • Pangaea Ultima or Amasia (~250 – ~400 million years from now (future supercontinent))
  • Australia-Antarctica-Eurafrasia (~130 million years from now (future supercontinent))
  • Australia-Eurafrasia (~60 million years from now (future supercontinent))
  • Eurafrasia (~30 million years from now (future supercontinent))
  • Americas (~ 15 mya present-day supercontinent)
  • Eurasia (~ 60 mya present-day supercontinent)
  • Gondwana (~600 – ~30 million years ago)
  • Laurasia (~ 300 – ~60 million years ago)
  • Pangaea (~300 – ~180 million years ago)
  • Euramerica (~ – ~300 million years ago)
  • Pannotia (~600 – ~540 million years ago)
  • Rodinia (~1.1 Ga – ~750 million years ago)
  • Columbia, also called Nuna, (~1.8–1.5 Ga ago)
  • Kenorland (~2.7 Ga. Neoarchean sanukitoid cratons and new continental crust formed Kenorland. Protracted tectonic magna plume rifting occurred 2.48 to 2.45 Ga and this contributed to the Paleoproterozoic glacial events in 2.45 to 2.22 Ga. Final breakup occurred ~2.1 Ga.)
  • Ur (~3 Ga ago, though probably not a supercontinent; but still however, the earliest known continent. Ur, however, was probably the largest, perhaps even the only continent three billion years ago, so one can argue that Ur was a supercontinent for its time, even if it had been smaller than Australia is today). Still an older rock formation now located in Greenland dates back from hadean
  • Komatii Formation (3.475 Ga)
  • Vaalbara (~3.6 Ga ago. Evidence is the Yilgarn Craton, Western Australia and the world-wide Archean greenstone belts that were subsequently spread out across Gondwana and Laurasia)
  • Yilgarn (Zircon crystals from the Jack Hills of the Narryer Gneiss Terrane, Yilgarn craton, Western Australia and also 300 km. south point to a continental crust formation between 4.4-4.3 Ga. Evidence is the high Oxygen-18 values of 8.5 and micro-inclusions of SiO2 in these zircon crystals consistent with growth from a granitic source supracrustal material, low-temperature interactions and a liquid ocean.)

Notes

1. ^ And to a lesser extent, the Americas, if taken as a whole

See also

External links

Oceanic crust      0-20 Ma
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Not to be confused with landmass.


Land mass refers to the total area of a country or geographical region (which may include discontinuous pieces of land such as islands). The Earth's total land mass is 148,939,063.133 km² (57,511,026.
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continent is one of several large landmasses on Earth. They are generally identified by convention rather than any strict criteria, but seven areas are commonly regarded as continents – they are (from largest in size to smallest): Asia, Africa, North America, South America,
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A craton (Greek kratos; "strength") is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. Some are over 2 billion years old.
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A terrane in paleogeography is an accretion that has collided with a continental nucleus, or "craton" but can be recognized by the foreign origin of its rock strata. The crustal block or fragment preserves its own distinctive geologic history, which is different from the
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Eurasia is an immense landmass covering about 53,990,000 km² (or about 10.6%) of the Earth's surface. Often reckoned as a single continent, Eurasia comprises the traditional continents of Europe and Asia, concepts which date back to classical antiquity and the borders for which are
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Palaeogeography (sometimes spelled paleogeography) is the study of the ancient geologic environments of the Earth's surface as preserved in the stratigraphic record.

Paleogeographic analysis is used in the detailed study of sedimentary basins in petroleum geology.
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continent is one of several large landmasses on Earth. They are generally identified by convention rather than any strict criteria, but seven areas are commonly regarded as continents – they are (from largest in size to smallest): Asia, Africa, North America, South America,
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The name "Vaalbara" is given to Earth's theorized first supercontinent. According to radiometric data of the encompassing cratons that constituted Vaalbara, it is believed to have existed 3.3 billion years ago (3.3 Ga) and possibly even as far back as 3.6 Ga.
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Annum is a Latin noun meaning year. It is the accusative singular of the second declension masculine noun annus (nominative), anni (genitive) [1] .

As a unit of time, it is defined as exactly 365.
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The name "Vaalbara" is given to Earth's theorized first supercontinent. According to radiometric data of the encompassing cratons that constituted Vaalbara, it is believed to have existed 3.3 billion years ago (3.3 Ga) and possibly even as far back as 3.6 Ga.
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Annum is a Latin noun meaning year. It is the accusative singular of the second declension masculine noun annus (nominative), anni (genitive) [1] .

As a unit of time, it is defined as exactly 365.
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Kenorland was one of the earliest supercontinents on Earth. It is believed to have formed during the Neoarchaean Era ~2.7 billion years ago (2.7 Ga) by the accretion of Neoarchaean cratons and the formation of new continental crust.
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Annum is a Latin noun meaning year. It is the accusative singular of the second declension masculine noun annus (nominative), anni (genitive) [1] .

As a unit of time, it is defined as exactly 365.
..... Click the link for more information.
Annum is a Latin noun meaning year. It is the accusative singular of the second declension masculine noun annus (nominative), anni (genitive) [1] .

As a unit of time, it is defined as exactly 365.
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A craton (Greek kratos; "strength") is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. Some are over 2 billion years old.
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Laurentia (also known as the North American craton), like all craton land, was created as continents moved about the surface of the Earth, bumping into other continents and drifting away.
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Baltica is a Late Proterozoic-Early Palaeozoic continent that now includes the East European craton of northwestern Eurasia. Baltica was created as an entity not earlier than 1.8 Ga.
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Yilgarn Craton is a large craton which constitutes the bulk of the Western Australian land mass. It is bounded by a mixture of sedimentary basins and Proterozoic fold and thrust belts. Zircon grains in the Jack Hills, Narryer Gneiss Terrane have been dated at ~4.
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The Kalahari craton occupies a large portion of South Africa and consists of the Kaapvaal, the Zimbabwe craton, the Limpopo belt, and the Namaqua Belt. It has formed a stable unit for the past 2.3 billion years (2.3 Ga).
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Columbia (also known as Nuna and, more recently, Hudsonland or Hudsonia) is the name of one of the Earth's earliest posited supercontinents, which existed approximately 1.8 to 1.5 billion years (Ga) ago in the Paleoproterozoic Era.
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Annum is a Latin noun meaning year. It is the accusative singular of the second declension masculine noun annus (nominative), anni (genitive) [1] .

As a unit of time, it is defined as exactly 365.
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Rodinia (from the Russian родина, or "motherland") refers to one of the oldest known supercontinents, which contained most or all of Earth's then-current landmass.
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The Paleozoic Era (from the Greek palaio, "old" and zoion, "animals", meaning "ancient life") is the earliest of three geologic eras of the Phanerozoic eon.
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Pangaea or Pangæa (IPA: /pænˈdʒiːə/[1], from παν, pan, meaning entire, and γαια, gaia, meaning Earth
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Laurasia (IPA: /lɔˈreɪʃiə, lɔˈreɪʃiʒə/[1]) was a supercontinent that most recently existed as a part of the split of the Pangaean supercontinent in the late
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Gondwana (IPA: /ɡɒnˈdwɑːnə/[1], originally Gondwanaland) included most of the landmasses in today's southern hemisphere, including Antarctica, South America, Africa, Madagascar,
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Plate tectonics (from Greek τέκτων, tektōn "builder" or "mason") is a theory of geology that has been developed to explain the observed evidence for large scale motions of the Earth's lithosphere.
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million (1,000,000), or one thousand thousand, is the natural number following 999,999 and preceding 1,000,001.

In scientific notation, it is written as 106[1]
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A year (from Old English gēr) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. By extension, this can be applied to any planet: for example, a "Martian year" is the time in which Mars completes its own orbit.
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