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Paleo-Pacific Ocean
Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the superocean that surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the history of Earth. During the Paleozoic– Mesozoic transition 250 it occupied almost 70% of Earth's surface. Its ocean floor has completely disappeared because of the continuous subduction along the continental margins on its circumference. Panthalassa is also referred to as the Paleo-Pacific ("old Pacific") or Proto-Pacific because the Pacific Ocean is a direct continuation of Panthalassa. Formation The supercontinent Rodinia began to break up 870–845 probably as a consequence of a superplume caused by mantle slab avalanches along the margins of the supercontinent. In a second episode 750 the western half of Rodinia started to rift apart: western Kalahari and South China broke away from the western margins of Laurentia; and by 720 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Panthalassa 250Ma
Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the superocean that surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the history of Earth. During the Paleozoic–Mesozoic transition 250 it occupied almost 70% of Earth's surface. Its ocean floor has completely disappeared because of the continuous subduction along the continental margins on its circumference. Panthalassa is also referred to as the Paleo-Pacific ("old Pacific") or Proto-Pacific because the Pacific Ocean is a direct continuation of Panthalassa. Formation The supercontinent Rodinia began to break up 870–845 probably as a consequence of a superplume caused by mantle slab avalanches along the margins of the supercontinent. In a second episode 750 the western half of Rodinia started to rift apart: western Kalahari and South China broke away from the western margins of Laurentia; and by 720 Austral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laurentia
Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and also the northwestern part of Scotland, known as the Hebridean Terrane. During other times in its past, Laurentia has been part of larger continents and supercontinents and itself consists of many smaller terranes assembled on a network of Early Proterozoic orogenic belts. Small microcontinents and oceanic islands collided with and sutured onto the ever-growing Laurentia, and together formed the stable Precambrian craton seen today. The craton is named after the Laurentian Shield, through the Laurentian Mountains, which received their name from the Saint Lawrence River, named after Lawrence of Rome. Interior platform In eastern and central Canada, much of the stable craton is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stikinia
Stikinia, or the Stikine terrane, is a terrane in British Columbia, Canada; the largest of the Canadian Cordillera. It formed as an independent, intraoceanic volcanic arc during the Paleozoic and Mesozoic. Stikinia forms the bedrock of numerous volcanoes in the southern portion of the Northern Cordilleran Volcanic Province (NCVP), a Miocene to Holocene geologic province that has its origins in continental rifting. Extent Until recently the Paleozoic rocks that form a non-continuous belt along the western margin of the NCVP (the Stikine assemblage) were only recognized in a restricted area in northern British Columbia, between the Stikine River and Taku River areas. In contrast, Mesozoic Stikinia rocks form a near-continuous belt that extends much farther to the north, leading some authors to question the nature of the unexposed Paleozoic basement north of the Taku River area. The following correlations have significant implications for tectonic reconstructions of the northern C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wrangellia Terrane
The Wrangellia Terrane (named for the Wrangell Mountains, Alaska) is a crustal fragment (terrane) extending from the south-central part of Alaska and along the Coast of British Columbia in Canada. Some geologists contend that Wrangellia extends southward to Oregon, although this is not generally accepted. Extent and terminology The term Wrangellia is confusingly applied to all of: * The Wrangell(ia) Terrane alone; * A composite terrane (CT) consisting of the Wrangell Terrane, Peninsular Terrane, and other rock units that were not originally part of the North American craton; * A composite terrane which also includes the Alexander Terrane. Earlier geologists sometimes used the term "Talkeetna Superterrane" to describe Wrangellia. Origin There are two conflicting hypotheses about whether the Wrangellia Superterrane originated at polar or equatorial latitudes: # That Wrangellia accreted at a northerly latitude near its current location (when North America, or Laurentia, was fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terrane
In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its own distinctive geologic history, which is different from that of the surrounding areas—hence the term "exotic" terrane. The suture zone between a terrane and the crust it attaches to is usually identifiable as a fault. A sedimentary deposit that buries the contact of the terrane with adjacent rock is called an overlap formation. An igneous intrusion that has intruded and obscured the contact of a terrane with adjacent rock is called a stitching pluton. Older usage of ''terrane'' simply described a series of related rock formations or an area having a preponderance of a particular rock or rock groups. Overview A tectonostratigraphic terrane is not necessarily an independent microplate in origin, since it may not contain the full thickness ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allochthon
upright=1.6, Schematic overview of a thrust system. The hanging wall block is (when it has reasonable proportions) called a nappe. If an erosional hole is created in the nappe that is called a window (geology)">window. A klippe is a solitary outcrop of the nappe in the middle of autochthonous material. An allochthon, or an allochthonous block, is a large block of rock which has been moved from its original site of formation, usually by low angle thrust faulting. An allochthon which is isolated from the rock that pushed it into position is called a klippe. If an allochthon has a "hole" in it so that one can view the autochthon (geology), autochthon beneath the allochthon, the hole is called a "window" (or Fenster). Etymology: Greek; 'allo' = other, and 'chthon' = earth. In generalized terms, the term is applied to any geologic units that originated at a distance from their present location For comparison, see also Autochthon. In the United States there are three notable al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Anomaly
In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying material. The magnetic variation (geomagnetic reversals) in successive bands of ocean floor parallel with mid-ocean ridges was important evidence for seafloor spreading, a concept central to the theory of plate tectonics. Measurement Magnetic anomalies are generally a small fraction of the magnetic field. The total field ranges from 25,000 to 65,000 nanoteslas (nT). To measure anomalies, magnetometers need a sensitivity of 10 nT or less. There are three main types of magnetometer used to measure magnetic anomalies: # The fluxgate magnetometer was developed during World War II to detect submarines. It measures the component along a particular axis of the sensor, so it needs to be oriented. On land, it is often oriented vertically, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pan-African Ocean
The Pan-African Ocean is a hypothesized paleo-ocean whose closure created the supercontinent of Pannotia. The ocean may have existed before the break-up of the supercontinent of Rodinia. The ocean closed before the beginning of the Phanerozoic Eon, when the Panthalassa Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the superocean that surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the history of Earth. During th ... ocean expanded, and was eventually replaced by it. See also * * References Historical oceans Proterozoic paleogeography {{palaeo-geo-stub ... [...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 Proterozoi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mirovia
Mirovia or Mirovoi (from Russian мировой, ''mirovoy'', meaning "global") was a hypothesized superocean which may have been a global ocean surrounding the supercontinent Rodinia in the Neoproterozoic Era, about 1 billion to 750 million years ago. Mirovia may be essentially identical to, or the precursor of, the hypothesized Pan-African Ocean, which followed the rifting of Rodinia. The Panthalassa (proto-Pacific) Ocean developed in the Neoproterozoic Era by subduction at the expense of the global Mirovia ocean. Geologic evidence suggests that the middle Neoproterozoic, the Cryogenian period, was an extreme ice age so intense that Mirovia may have been completely frozen to a depth of 2-km. This is part of the Snowball Earth hypothesis. See also *Panthalassa Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the superocean that surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aulacogen
An aulacogen is a failed arm of a triple junction. Aulacogens are a part of plate tectonics where oceanic and continental crust is continuously being created, destroyed, and rearranged on the Earth’s surface. Specifically, aulacogens are a rift zone, where new crust is formed, that is no longer active. Origin of term The term ''aulacogen'' is derived from Greek ''aulax'' 'furrow' and was suggested by the Soviet geologist Nikolay Shatsky in 1946. Formation A triple junction is the point where three tectonic plates meet; the boundaries of these plates are characterized by divergence, causing a rift zone or spreading center; a transform fault; or convergence causing subduction or uplift of crust and forming mountains. The failed arm of a triple junction can be either a transform fault that has been flooded with magma, or more commonly, an inactive rift zone. Aulacogen formation starts with the termination of an active rift zone, which leaves behind a graben-like formation. Over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
