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Paleo-Pacific
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 Austra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South China (continent)
The South China Craton or South China Block is one of the Precambrian continental blocks in China. It is traditionally divided into the Yangtze Plate, Yangtze Block in the NW and the Cathaysia, Cathaysia Block in the SE. The Jiangshan–Shaoxing Fault represents the Suture (geology), suture boundary between the two sub-blocks. Recent study suggests that the South China Block possibly has one more sub-block which is named the Tolo Terrane. The oldest rocks in the South China Block occur within the Huangling Complex, Kongling Complex, which yields Uranium–lead dating, zircon U–Pb ages of 3.3–2.9 Ga. There are three important reasons to study the South China Block. First, South China hosts a great deal of Rare-earth element, rare-earth element (REE) ores. Second, the South China Block is a key component of the Rodinia, Rodinia supercontinent. Therefore, such study helps us understand more about the supercontinent cycle. Third, almost all major known clades of Triassic marine rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pacific Ocean 180Ma
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continents of Asia and Oceania in the west and the Americas in the east. At in area (as defined with a southern Antarctic border), this largest division of the World Ocean—and, in turn, the hydrosphere—covers about 46% of Earth's water surface and about 32% of its total surface area, larger than Earth's entire land area combined .Pacific Ocean . '' Britannica Concise.'' 2008: Encyclopædia Britannica, Inc. The centers of both the |
Triple Junction
A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction each of the three boundaries will be one of three types – a ridge (R), trench (T) or transform fault (F) – and triple junctions can be described according to the types of plate margin that meet at them (e.g. Fault-Fault-Trench, Ridge-Ridge-Ridge, or abbreviated F-F-T, R-R-R). Of the ten possible types of triple junction only a few are stable through time ('stable' in this context means that the geometrical configuration of the triple junction will not change through geologic time). The meeting of four or more plates is also theoretically possible but junctions will only exist instantaneously. History The first scientific paper detailing the triple junction concept was published in 1969 by Dan McKenzie and W. Jason Morgan. The term had traditionally been used for the intersection of three divergent boundaries or spreading ridges. These three divergent boundaries idea ... [...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 thick ... [...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 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 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 allochthons; all of which were displaced nearly 50 km (31 miles) along thrust faults. The Golconda and Rober ... [...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 ... [...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 Proter ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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