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Grunehogna Craton
Vaalbara is a hypothetical Archean supercontinent consisting of the Kaapvaal craton (now in eastern South Africa) and the Pilbara Craton (now in north-western Western Australia). E. S. Cheney derived the name from the last four letters of each craton's name. The two cratons consist of continental crust dating from 2.7 to 3.6 Ga, which would make Vaalbara one of Earth's earliest supercontinents. Existence and lifespan There has been some debate as to when and even if Vaalbara existed. An Archaean– Palaeoproterozoic (2.8–2.1 Ga) link between South Africa and Western Australia was first proposed by Alan Button in 1976. He found a wide range of similarities between the Transvaal Basin in South Africa and the Hamersley Basin in Australia. Button, however, placed Madagascar between Africa and Australia and concluded that Gondwana must have had a long stable tectonic history. Similarly, in the reconstruction of Rogers 1993, 1996 the oldest continent is Ur. In Rogers' reconstr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercontinent
In geology, a supercontinent is the assembly of most or all of Earth's continent, continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leaves room for interpretation and is easier to apply to Precambrian times. To separate supercontinents from other groupings, a limit has been proposed in which a continent must include at least about 75% of the continental crust then in existence in order to qualify as a supercontinent. Moving under the forces of plate tectonics, supercontinents have assembled and dispersed multiple times in the geologic past. According to modern definitions, a supercontinent does not exist today; the closest is the current Afro-Eurasian landmass, which covers approximately 57% of Earth's total land area. The last period in which the continental landmasses were near to one another was 336 to 175 million years ago, forming the supercontinent Pangaea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rodinia
Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago (Ga) and broke up 750–633 million years ago (Ma). were probably the first to recognise a Precambrian supercontinent, which they named "Pangaea I." It was renamed "Rodinia" by , who also were the first to produce a plate reconstruction and propose a temporal framework for the supercontinent. Rodinia formed at c. 1.23 Ga by accretion and collision of fragments produced by breakup of an older supercontinent, Columbia, assembled by global-scale 2.0–1.8 Ga collisional events.; Rodinia broke up in the Neoproterozoic, with its continental fragments reassembled to form Pannotia 633–573 Ma. In contrast with Pannotia, little is known about Rodinia's configuration and geodynamic history. Paleomagnetic evidence provides some clues to the paleolatitude of individual pieces of the Earth's crus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Antarctica
East Antarctica, also called Greater Antarctica, constitutes the majority (two-thirds) of the Antarctic continent, lying primarily in the Eastern Hemisphere south of the Indian Ocean, and separated from West Antarctica by the Transantarctic Mountains. It is generally greater in elevation than West Antarctica, and includes the Gamburtsev Mountain Range in the center. The geographic South Pole is located within East Antarctica. Apart from small areas of the coast, East Antarctica is permanently covered by ice and it has relatively low biodiversity, with only a small number of species of terrestrial plants, animals, algae, and lichens. The coasts are the breeding ground for various seabirds and penguins, and the leopard seal, Weddell seal, elephant seal, crabeater seal and Ross seal breed on the surrounding pack ice in summer. Location and description Almost completely covered in thick, permanent ice, East Antarctica comprises Coats Land, Queen Maud Land, Enderby Land, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Queen Maud Land
Queen Maud Land () is a roughly region of Antarctica Territorial claims in Antarctica, claimed by Norway as a dependent territory. It borders the claimed British Antarctic Territory 20th meridian west, 20° west, specifically the Caird Coast, Coats Land on the West, and the Australian Antarctic Territory 45th meridian east, 45° east, specifically Enderby Land on the East. In addition, a small unclaimed area from 1939 was annexed in June 2015. Positioned in East Antarctica, it makes out about one-fifth of the continent, and is named after the Norwegian Maud of Wales, Queen Maud (1869–1938). In 1930, the Norwegian Hjalmar Riiser-Larsen was the first person known to have set foot in the territory. On 14 January 1939, the territory was claimed by Norway. On 23 June 1961, Queen Maud Land became part of the Antarctic Treaty System, making it a demilitarised zone. It is one of dependencies of Norway, two Antarctic claims made by Norway, the other being Peter I Island. They are adm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
São Francisco Craton
SAO or Sao may refer to: Places * Sao civilisation, in Middle Africa from 6th century BC to 16th century AD * Sao, a town in Boussé Department, Burkina Faso * Serb Autonomous Regions (''Srpska autonomna oblast'', SAO), during the breakup of Yugoslavia Science and technology * Smithsonian Astrophysical Observatory of the Smithsonian Institution in Cambridge, Massachusetts, U.S. ** Smithsonian Astrophysical Observatory Star Catalog, which assigns SAO catalogue entries * Special Astrophysical Observatory of the Russian Academy of Science (SAO RAS) * Session-At-Once, a recording mode for optical discs Transportation * Saco Transportation Center, a train station in Saco, Maine, U.S., station code SAO * Sahel Aviation Service, Mali, ICAO airline code SAO * Airports in Greater São Paulo, Brazil, IATA airport code SAO People * Ligi Sao (born 1992), a Samoan rugby league player * Ron Sao, Western Australian politician Other uses * Sao (moon), a satellite of Neptune * S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleomagnetism
Paleomagnetism (occasionally palaeomagnetism) is the study of prehistoric Earth's magnetic fields recorded in rocks, sediment, or archeological materials. Geophysicists who specialize in paleomagnetism are called ''paleomagnetists.'' Certain magnetic minerals in rock (geology), rocks can record the direction and intensity of Earth's magnetic field at the time they formed. This record provides information on the past behavior of the geomagnetic field and the past location of Plate tectonics, tectonic plates. The record of geomagnetic reversals preserved in Volcanic rock, volcanic and sedimentary rock sequences (magnetostratigraphy) provides a time-scale that is used as a geochronology, geochronologic tool. Evidence from paleomagnetism led to the revival of the continental drift hypothesis and its transformation into the modern theory of plate tectonics. Apparent polar wander paths provided the first clear geophysical evidence for continental drift, while marine magnetic anomaly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
