|
List Of Supercontinents
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. Supercontinents have assembled and dispersed multiple times in the geologic past (see table). According to modern definitions, a supercontinent does not exist today; the closest in existence to a supercontinent is the current Afro-Eurasian landmass, which covers approx. 57% of Earth's total land area. The last time the continental landmasses were near to one another was 336 to 175 million years ago as the supercontinent, Pangaea. The positions of con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pangea Assembly 250
Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia (continent), Siberia during the Carboniferous approximately 335 million years ago, and began to break apart about 200 million years ago, at the end of the Triassic–Jurassic extinction event, Triassic and beginning of the Jurassic. In contrast to the present Earth and its distribution of continental mass, Pangaea was centred on the equator and surrounded by the superocean Panthalassa and the Paleo-Tethys Ocean, Paleo-Tethys and subsequent Tethys Ocean, Tethys Oceans. Pangaea is the most recent supercontinent to have existed and the first to be reconstructed by geologists. Origin of the concept The name "Pangaea" is derived from Ancient Greek ''pan'' (, "all, entire, whole") and ''Gaia (mythology), Gaia'' or Gaea (, "Mother goddess, Mother Earth, land"). The concept that the continents ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sclavia Craton
The Sclavia Craton is a late Archean super craton thought to be parental to the Slave and Wyoming Cratons in North America, the Dharwar Craton in southern India, and the Zimbabwe Craton in southern Africa. Sclavia was proposed by who estimated the number of Archean cratons to be about 35; cratonic fragments which he suggested were derived from a single or a few supercratons. The break-up of Sclavia, and possibly other continents or supercratons, can be linked to a global pulse of magmatic activity around 2.33–2.1 Gya probably caused by increased mantle plume activity. Related results of this mantle activity include the 2.3 Ga-old Precambrian dyke swarms in the Dharwar Craton The Dharwar Craton is an Archean continental crust craton formed between 3.6-2.5 billion years ago ( Ga), which is located in southern India and considered as the oldest part of the Indian peninsula. Studies in the 2010s suggest that the craton c ... in southern India which were emplaced in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plate Tectonics
Plate tectonics (from the la, label= Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large tectonic plates which have been slowly moving since about 3.4 billion years ago. The model builds on the concept of '' continental drift'', an idea developed during the first decades of the 20th century. Plate tectonics came to be generally accepted by geoscientists after seafloor spreading was validated in the mid to late 1960s. Earth's lithosphere, which is the rigid outermost shell of the planet (the crust and upper mantle), is broken into seven or eight major plates (depending on how they are defined) and many minor plates or "platelets". Where the plates meet, their relative motion determines the type of plate boundary: '' convergent'', '' divergent'', or '' transform''. Earthquakes, volcanic activity, mountain-building, and ocea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lid Tectonics
Lid tectonics, commonly thought of as stagnant lid tectonics, is the type of tectonics that is believed to exist on several planets and moons in the Solar System, and possibly existed on Earth during the early part of its history. The lid is the equivalent of the lithosphere in plate tectonics, formed of solid silicate minerals (or solid ice in the case of icy planets and moons). The relative stability and immobility of the strong cooler lids leads to stagnant lid tectonics, which has greatly reduced amounts of horizontal tectonics compared with plate tectonics (which can also be described as mobile lid tectonics). The presence of a stagnant lid above a convecting mantle was recognised as a possible stable regime for convection on Earth, in contrast to the well-attested mobile plate tectonics of the current eon. Formation A lid tectonic regime arises when the cold upper lithosphere is too viscous to participate in the underlying flow of the mantle. The lid's yield strength is hig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plate Reconstruction
:''This article describes techniques; for a history of the movement of tectonic plates, see Geological history of Earth.'' Plate reconstruction is the process of reconstructing the positions of tectonic plates relative to each other (relative motion) or to other reference frames, such as the earth's magnetic field or groups of hotspots, in the geological past. This helps determine the shape and make-up of ancient supercontinents and provides a basis for paleogeographic reconstructions. Defining plate boundaries An important part of reconstructing past plate configurations is to define the edges of areas of the lithosphere that have acted independently at some time in the past. Present plate boundaries Most present plate boundaries are easily identifiable from the pattern of recent seismicity. This is now backed up by the use of geodetic data, such as GPS/GNSS, to confirm the presence of significant relative movement between plates. Past plate boundaries Identifying past (but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ediacaran
The Ediacaran Period ( ) is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and the beginning of the Phanerozoic Eon. It is named after the Ediacara Hills of South Australia. The Ediacaran Period's status as an official geological period was ratified in 2004 by the International Union of Geological Sciences (IUGS), making it the first new geological period declared in 120 years. Although the period takes its name from the Ediacara Hills where geologist Reg Sprigg first discovered fossils of the eponymous Ediacaran biota in 1946, the type section is located in the bed of the Enorama Creek within Brachina Gorge in the Flinders Ranges of South Australia, at . The Ediacaran marks the first appearance of widespread multicellular fauna following the end of Snowball Earth glaciation events, the so-called Ediacaran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accretion (geology)
Accretion, in geology, is a process by which material is added to a tectonic plate at a subduction zone, frequently on the edge of existing continental landmasses. The added material may be sediment, volcanic arcs, seamounts, oceanic crust or other igneous features. Description Accretion involves the addition of material to a tectonic plate via subduction, the process by which one plate is forced under the other when two plates collide. The plate which is being forced down, the subducted plate, is pushed against the upper, over-riding plate. Sediment on the ocean floor of the subducting plate is often scraped off as the plate descends. This accumulated material is called an accretionary wedge (or accretionary prism), which is pushed against and attaches to the upper plate. In addition to accumulated ocean sediments, volcanic island arcs or seamounts present on the subducting plate may be amalgamated onto existing continental crust on the upper plate, increasing the cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesoproterozoic
The Mesoproterozoic Era is a geologic era that occurred from . The Mesoproterozoic was the first era of Earth's history for which a fairly definitive geological record survives. Continents existed during the preceding era (the Paleoproterozoic), but little is known about them. The continental masses of the Mesoproterozoic were more or less the same ones that exist today, although their arrangement on the Earth's surface was different. Major events and characteristics The major events of this era are the breakup of the Columbia supercontinent, the formation of the Rodinia supercontinent, and the evolution of sexual reproduction. This era is marked by the further development of continental plates and plate tectonics. The supercontinent of Columbia broke up between 1500 and 1350 million years ago, and the fragments reassembled into the supercontinent of Rodinia around 1100 to 900 million years ago, on the time boundary between the Mesoproterozoic and the subsequent Neoprotero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoarchean
The Neoarchean (; also spelled Neoarchaean) is the last geologic era in the Archean eon that spans from 2800 to 2500 million years ago—the period being defined chronometrically and not referencing a specific level in a rock section on Earth. The era is marked by major developments in complex life and continental formation. Complex life This era saw the rise of oxygen in the atmosphere after oxygenic photosynthesis evolved as early as the Mesoarchean era. The environmental changes that occurred in the Neoarchean such as its developing atmospheric and soil compositions drastically differentiated the era from others in its encouragement of microbial metabolisms to evolve and diversify. The era could have also seen pre-biotic organic molecules being brought to Earth through meteorites, comets, or through abiotic reactions. The growth of juvenile continental crust as well as the onset of plate tectonics in the Archean allowed for the colonization of a larger variety of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Year
A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked. A calendar year is an approximation of the number of days of the Earth's orbital period, as counted in a given calendar. The Gregorian calendar, or modern calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars. For the Gregorian calendar, the average length of the calendar yea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pannotia
Pannotia (from Greek: '' pan-'', "all", '' -nótos'', "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neoproterozoic supercontinent that formed at the end of the Precambrian during the Pan-African orogeny (650–500 Ma), during the Cryogenian period and broke apart 560 Ma with the opening of the Iapetus Ocean, in the late Ediacaran and early Cambrian. Pannotia formed when Laurentia was located adjacent to the two major South American cratons, Amazonia and Río de la Plata. The opening of the Iapetus Ocean separated Laurentia from Baltica, Amazonia, and Río de la Plata. In 2022 the whole concept of Pannotia has been put into question by scientists who argue its existence is not supported by geochronology, "the supposed landmass had begun to break up well before it was fully assembled". Origin of concept J. D. A. Piper was probably the first to propose a Proter ... [...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 and broke up 750–633 million years ago. 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 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 million years ago. In contrast with Pannotia, little is known yet about the exact configuration and geodynamic history of Rodinia. Paleomagnetic evidence provides some clues to the paleolatitude of individual pieces of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
