In fact, Mike was canned by the Packers last season after he and A-Rodge reportedly rifted on and off throughout their final years together in Wisconsin.
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Among the work from the Western region — an area deeply rifted by conflict, due to the Anglo-American interest in prospecting for gold — sits a beautiful basket woven in 1907 with a "Harbor Lights" motif that was a trademark design of Washoe artist Louisa Keyser.
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Cathaysia was a microcontinent or a group of terranes that rifted off Gondwana during the Late Paleozoic.
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No continental rocks exist in western Nevada from more than 700 million years ago, because the western part of the region was rifted away, becoming part of current day Siberia.
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The Kenn Plateau is a large piece of submerged continental crust off northeastern Australia that rifted from northeastern Australia about 63-52 mya, along with other nearby parts of the Zealandia continent.
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After the collision, the continent rifted away during late Ordovician, so that Precordillera was no longer attached to Laurentia and stuck to the western Gondwana. This model is also known as "paired rift margin".
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The Paleo-Tethys had closed from west to east, creating the Cimmerian Orogeny. Pangaea, which looked like a C, with the new Tethys Ocean inside the C, had rifted by the Middle Jurassic, and its deformation is explained below.
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In the history of Earth many tectonic plates have come into existence and have over the intervening years either accreted onto other plates to form larger plates, rifted into smaller plates, or have been crushed by or subducted under other plates.
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The Bahía de Banderas is regarded by most geologists as the original attachment point for the southern cape of the Baja California Peninsula before it was rifted off the North American Plate millions of years ago, forming the Gulf of California.
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Avalonia is named for the Avalon Peninsula in Newfoundland. Avalonia developed as a volcanic arc on the northern margin of Gondwana. It eventually rifted off, becoming a drifting microcontinent. The Rheic Ocean formed behind it, and the Iapetus Ocean shrank in front.
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Within the past 66 million years, the Congo Basin has continued to sag, surrounded by topographic highs on all sides. In the Miocene, the basin closed due to flank uplift at the Atlantic rifted margin and gorges and rapids formed in the Mayombe mountains.
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18, p. 691-712Metcalfe, I., 2002, "Permian tectonic framework and palaeogeography of SE Asia", Journal of Asian Earth Sciences, v. 20, p. 551-566 The Cimmeria was separated from Gondwana around 400 mya during the Devonian and rifted towards Laurasia, the northeastern arm of Pangea.
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Farther north, subduction of the Pacific Plate has led to extensive volcanism, including the Coromandel and Taupo Volcanic Zones. Associated rifting and subsidence has produced the Hauraki Graben and more recently the Whakatane Graben and Wanganui Basin. Volcanism on Zealandia has also taken place repeatedly in various parts of the continental fragment before, during and after it rifted away from the supercontinent Gondwana. Although Zealandia has shifted approximately to the northwest with respect to the underlying mantle from the time when it rifted from Antarctica, recurring intracontinental volcanism exhibits magma composition similar to that of volcanoes in previously adjacent parts of Antarctica and Australia.
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Transitional crust, separating true oceanic and continental crusts, is the foundation of any passive margin. This forms during the rifting stage and consists of two endmembers: Volcanic and Non-Volcanic. This classification scheme only applies to rifted and transtensional margin; transitional crust of sheared margins is very poorly known.
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The formation of the Somali Plate began 60 million years ago and accelerated at the end of the Oligocene, approximately 23 million years ago. As the Arabian Plate and Somali Plate rifted apart, forming the Gulf of Aden through sea floor spreading in the Late Miocene, magma intruded between the two plates.
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By the end of the era, the continents had rifted into nearly their present forms, though not their present positions. Laurasia became North America and Eurasia, while Gondwana split into South America, Africa, Australia, Antarctica and the Indian subcontinent, which collided with the Asian plate during the Cenozoic, giving rise to the Himalayas.
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In the early Permian, a continental block rifted from Gondwanaland. The continental plate has been variously termed: Shan-Thai, Sibumasu, or Sinoburmalaya. This continental block harbors features of glaciogenic marine diamictite unit, indicating its origin from Gondwanaland. The Shan-Thai block was probably located northwest of Australia plate during the Gondwanaland period.
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This belt of rock was a part of what is called Laurentia, thought by some geologists to be the core of Rodinia.This belt stops suddenly at its western margin, leading geologists to suspect that some piece of crust had rifted away from what is now the West Coast of the United States.
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The lakes in this area (e.g. Lake Tanganyika and Lake Rukwa) are located in highly rifted basins and have an inter-fingering relationship with faults. Many of the lakes are bounded by normal or strike-slip faults. The extension rate for this rift starts at about in the north, and declines to the south.
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During the break-up of Pangea, the North American plate began to separate from the South American plate. The two plates rifted away from each other forming the "Proto-Caribbean Seaway", an 1800 km wide region of oceanic crust. As this rifting occurred, the Caribbean plate began its eastward migration from the Pacific region.
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Sheared margins form where continental breakup was associated with strike-slip faulting. A good example of this type of margin is found on the south-facing coast of west Africa. Sheared margins are highly complex and tend to be rather narrow. They also differ from rifted passive margins in structural style and thermal evolution during continental breakup.
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The Otway Basin that hosts Kanawinka occupies the southern margin of South Australia and Victoria, and also has a significant portion located offshore. This basin formed when Australia rifted away from Gondwana (the southern supercontinent), which occurred about 95 million years ago (Drexel et al. 1993) . The sequence of sediments in the basin was deposited from Jurassic through to recent times.
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126, p. 271-281. The basin appears to have been a closed "lacustrine" environment, or at least not completely open marine. Depositional environments are thought to have ranged from ancient floodplains and exposed mudflats to deep water. Evidence of the basin-bounding faults exists on all sides of the Belt basin except the west, which rifted away during subsequent continental breakup.
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The channel of Nizhnyaya Tunguska with its tributaries constitutes dense network of rivers and creeks which creates convenient summer pathways through the wide rifted valley of Eastern Siberia. Historically, the river was used as a route for the fur trade, fishery, for transportation of goods and mineral resources. Hunting and fur trade is still a significant part of the local economy.
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This was rifted in Toarcian times (Early Jurassic 190 Ma). Active rifting was complete by 160 Ma. After this thermal subsidence occurred till the end of Cretaceous. During this time rifting separated North America from Africa forming a transform zone . In the late Triassic and early Jurassic there were two stages of rifting involving extension and subsidence on the western margin of Iberia.
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The Appalachian-Ouachita orogen along the southeastern margin of the North American craton includes a late Paleozoic fold-thrust belt with a thin-skinned flat-and-ramp geometry, related to lateral and vertical variations in rock lithologies. The décollement surface varies along and across strike. Promontories and embayments in the late Precambrian-early Paleozoic rifted margin are preserved in the décollement geometry.
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The climate Kuehneotherium lived in was hot and dry during this part of the early Mesozoic. Conifer plants thrived and spread throughout Pangaea. As the continents rifted apart during the Early Jurassic the climate was more humid. Ferns, horsetails, cycads, and mosses were common in both the Triassic and Jurassic, however they were more prevalent in the more humid Jurassic Period.
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It attached to Laurasia completely around 280 mya during the Late Permian. Sibumasu terranes on the other hand, only started to separate from Gondwana during the Early Permian and rifted towards Indochina. The collision of Sibumasu terranes and Indochina terranes during 200mya Late Triassic resulted in the closure of the Paleo-Tethys Ocean and formation of the modern Titiwangsa Mountain belts.
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Sedimentary rocks overlay most of these ancient rocks. The oldest sediments were deposited on the flanks of a rifted continental margin, or passive margin that developed during Cambrian time. This margin existed until Laurasia and Gondwana collided in the Pennsylvanian subperiod to form Pangea. This is the buried crest of the Appalachian Mountains–Ouachita Mountains zone of Pennsylvanian continental collision.
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Antarctic Peninsula previous plate configurations. As Gondwana broke apart, the Antarctic Peninsula started to take on its modern shape. Roughly 220 million years ago, the continents of Antarctica, South America, and Africa rifted apart. This rifting created low relief basins which allowed for the transport of sediments and subsequent deposition of sedimentary rocks, which happen to be the oldest on the peninsula.
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The Chimanimani Mountains extend through the eastern part of the district, stretching for some 50 km (31 mi) and forming the border with Mozambique. The mountains are distinguished by large peaks, carved from a rifted quartzite massif. The highest peak is Monte Binga at 2,436 m (8,005 ft). Chimanimani National Park (171.1 km²) protects the Zimbabwean portion of the range.
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The geology of Socotra is part of the national geology of Yemen. Ancient Precambrian metamorphic rocks are intruded by younger igneous rocks, overlain by limestones and other marine sediments that deposited during marine transgression periods in the Cretaceous and the past 66 million years of the Cenozoic. The island is on the Somali Plate, which rifted away from the Arabian mainland within the past 60 million years.
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Klamath Mountains is the name given to one of California's eleven geomorphic provinces. The rocks of the Klamath Mountains originated as island arcs and continental fragments in the Pacific Ocean. The island masses consisted of rifted fragments of pre-existing continents and volcanic island masses created over subduction zones. These island masses contain rocks as old as 500 million years, dating to the early Paleozoic Era.
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The Proto-Pacific opened and Rodinia began to breakup during the Neoproterozoic (c. 750–600 Mya) as Australia-Antarctica (East Gondwana) rifted from the western margin of Laurentia, while the rest of Rodinia (West Gondwana and Laurasia) rotated clockwise and drifted south. Earth subsequently underwent a series of glaciations - the Varanger (c. 650 Mya, also known as Snowball Earth) and the Rapitan and Ice Brook glaciations (c.
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The core of Arctica was the Canadian Shield, which named Kenorland. They argued that this continent formed around 2.5 Ga then rifted before reassembling along the 1.8 Ga Trans-Hudson and Taltson-Thelon orogenies. These two orogenies are derived from continental crust (not oceanic crust) and were probably intracontinental, leaving Kenorland intact from 2.5 Ga to present. Correlations between orogenies in Canada and Siberia remain more controversial.
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Geologically, the range is considered a monocline; part of a rifted volcanic margin. The Lebombo monocline was aligned with the Explora Escarpment off-shore Dronning Maud Land, Antarctica, before the break-up of Gondwana. The Lebombo monocline strikes N-S and dips to the east. It is composed of a sequence of Jurassic age volcanic rock, both basaltic lavas and rhyolitic flows and tuffs.
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A second phase took place during the Mesozoic Era (before ~66 My). It consisted of a widespread extension of the Earth's crust that rifted and separated the continents mentioned above. This extension was responsible for the formation of many thick intracontinental sedimentary basins including the present Atlas. Most of the rocks forming the surface of the present High Atlas were deposited under the ocean at that time.
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The Newark Lowlands of the Newark Basin extends into New York between the Hudson Highlands and the Manhattan Prong. The basin formed beginning 220 million years ago during the late Triassic as Pangea rifted apart. Failed rift basins like the Newark Basin filled with thick sequences of sediment. The Stockton Formation is the lowest unit, with feldspar rich sandstone and conglomerate alternating with layers of shale mudstone.
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Meanwhile, Baltica collided with Siberia and Kazakhstania which resulted in the Uralian orogeny and Laurasia. Pangaea was finally amalgamated in the Late Carboniferous-Early Permian, but the oblique forces continued until Pangaea began to rift in the Triassic. In the eastern end collisions occurred slightly later. The North China, South China, and Indochina blocks rifted from Gondwana during the middle Paleozoic and opened the Proto-Tethys Ocean.
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The Mediterranean Sea, particularly during the Messinian salinity crisis, is a prime example. # Rifted boundaries/passive margins – Also known as divergent boundaries, these areas begin as rift basins, where extension is pulling apart the crust. If this rifting allows water to flood the resulting valley, salt deposition can occur. Examples include the Campos Basin, Brazil, Kwanza Basin, West Africa, and the Gulf of Mexico.
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Some islands lie on sections of continental crust that have rifted and drifted apart from a main continental landmass. While not considered continents because of their relatively small size, they may be considered microcontinents. Madagascar, the largest example, is usually considered an island of Africa, but its divergent evolution has caused it to be referred to as "the eighth continent" from a biological perspective.
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Satellite picture of the gulf Geologic evidence is widely interpreted by geologists as indicating the gulf came into being around 5.3 million years ago as tectonic forces rifted the Baja California Peninsula off the North American Plate.Hamilton, W.B., 1961, Origin of the Gulf of California: GSA Bull., 72, 1307–1318. As part of this process, the East Pacific Rise propagated up the middle of the Gulf along the seabed.
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The 2,125- to 2,090-million-year-old mafic magmatic events affecting the Superior and Wyoming cratons show the hotspot having moved west from Sudbury, and the two provinces have rifted so that they are separated by . That narrowest distance between the two cratons is from Sudbury, in east- central South Dakota. The Blue Draw Metagabbro is now west of Sudbury and south of the Superior province's southern border.
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The modern Manihiki Plateau rifted from the Hikurangi Plateau, now located adjacent to New Zealand, in the Early Cretaceous. In the Early Cretaceous the Manihiki Plateau was much shallower, below sea level or less. Shortly after emplacement the initiation of the Tongareva triple junction resulted in extension, upwelling and rifting. Renewed rifting at about 116 Ma created the eastern margin, the Manihiki Scarp, and separated Manihiki and Hikurangi.
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The Cenozoic Era covers the million years since the Cretaceous–Paleogene extinction event up to and including the present day. By the end of the Mesozoic era, the continents had rifted into nearly their present form. Laurasia became North America and Eurasia, while Gondwana split into South America, Africa, Australia, Antarctica and the Indian subcontinent, which collided with the Asian plate. This impact gave rise to the Himalayas.
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They are the Qinling-Dabie Orogen in the north and the Song Ma suture in the south. The current configuration of continental blocks is the result of an array of rifting and collision events over more than 400 million years. Simply put, the geological evolution of Southeast Asia is characterized by the Gondwana dispersion and Asian accretion. The Southeast Asia continental blocks successively rifted apart from the Gondwana.
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From 170 to 120 Ma more than 200 km of left lateral slip occurred between Europe and Iberia as it was rifted from the Grand Banks. From 120 to 83 Ma 115 km of convergence in Sardinia and Corsica region. At 83 Ma convergence with Europe happened till 67.7 Ma when it stopped moving with respect to Europe. In the Eocene 55–46 Ma there was right lateral slip.
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The total amount of uplift produced by this mechanism could be as much as 500 m. Other geoscientists have implied diapirism in the asthenosphere as being the cause of uplift. One hypothesis states that the early uplift of the Scandinavian Mountains could be indebted to changes in the density of the lithosphere and asthenosphere caused by the Iceland plume when Greenland and Scandinavia rifted apart about 53 million years ago.
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The Louisiade Plateau, also called the Louisiade Rise, is a poorly studied oceanic plateau in the northern Coral Sea of the South Pacific Ocean. It has been described as a continental fragment that rifted away from the northwestern continental margin of Australia but its position at the northern end of the Tasmantid Seamount Chain also suggests that the Louisiade Plateau might be a large igneous province formed by the arrival of the Tasmantid hotspot.
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She performed refraction measurements to study the seismic anisotropy in the upper mantle, showing that the maximum and minimum velocity was consistent with seafloor spreading. Alongside extensive studies of the Atlantic and Pacific Ocean, Keen used biostratigraphic and metamorphic data to analyse the exploratory wells around Labrador. She showed that the subsidence of basement followed similar depth-age curves to the oceanic lithosphere. Keen developed thermal-mechanical models and applied them to rifted continental margins.
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Twenty-one of the thirty seven largest aquifers "have exceeded sustainability tipping points and are being depleted" and thirteen of them are "considered significantly distressed". A plateau more than high extends across much of the Arabian Peninsula. The plateau slopes eastwards from the massive, rifted escarpment along the coast of the Red Sea, to the shallow waters of the Persian Gulf. The interior is characterised by cuestas and valleys, drained by a system of wadis.
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The ANS foreland basin was broken down into three depositional and tectonic sequences that define the deposits and structure of the basin. From the Mississippian to Jurassic a carbonate ramp built out to the south on the passive margin of the Arctic Alaskan Plate. The Arctic Alaskan Plate was then rifted and rotated in the Early to Mid Cretaceous. This rifting created the Barrow Arch that separates the ANS from the Canadian Basin.
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Volcanic passive margins represent one endmember transitional crust type, the other endmember (amagmatic) type is the rifted passive margin. Volcanic passive margins also are marked by numerous dykes and igneous intrusions within the subsided continental crust. There are typically a lot of dykes formed perpendicular to the seaward-dipping lava flows and sills. Igneous intrusions within the crust cause lava flows along the top of the subsided continental crust and form seaward-dipping reflectors.
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In contrast to Rodinia, Pannotia was short-lived. It rifted apart 545 million years ago, or only 65 million years after it formed. This resulted in the creation of at least four continents, namely Baltica, Siberia, Gondwana and Laurentia. By the Early Cambrian 514 million years ago, Laurenta was located on the equator, Baltica was south of Laurenta, Siberia was just south of the equator east of Laurenta, and Gondwana lied mostly in the Southern Hemisphere.
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In fact, Cenozoic sediments cover much of Somaliland. The formation of the Somali Plate began 60 million years ago and accelerated at the end of the Oligocene, approximately 23 million years ago. As the Arabian Plate and Somali Plate rifted apart, forming the Gulf of Aden through sea floor spreading in the Late Miocene magma intruded between the two plates. Of particular significance for Somaliland, rifting in the Oligocene and Miocene reactivated Mesozoic normal faults, forming the Guban Basin.
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The oldest rocks in Nevada are in the East Humboldt Range in the northeast, with lead isotope data suggesting an age of 2.5 billion years, at the boundary of the Archean and Proterozoic. Metamorphic and igneous rocks formed 1.7 billion years ago underlie Clark County and the populous areas around Las Vegas. The region was part of the supercontinent Rodinia one billion years ago, situated at the equator. The continent rifted apart between 700 and 600 million years ago.
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One end of the TAO was a series of terranes (Avalonia–Carolina–Cadomia) which were rifted off the western margin of Gondwana and added to Laurentia in the Late Palaeozoic, while its other end probably reached past Australia into New Guinea. In 1937 Alexander du Toit proposed the Samfrau Orogeny as an evidence for Gondwana. His concept includes the orogenies of West Gondwana and orogenies that are now considered separate events but excludes those of East Gondwana.
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Earthquakes occur deep within bedrock. Most bedrock beneath the Charleston area was assembled as continents collided to form a supercontinent about 500-300 million years ago, raising the Appalachian Mountains. Most of the rest of the bedrock formed when the supercontinent rifted apart about 200 million years ago to form what are now the southeastern U.S., the Atlantic Ocean, and Africa. Today the Charleston area is far from the nearest plate boundary, which is in the Caribbean Sea.
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Subsistence related to this caused deep deposits of sediments on the east and some sediment remnants in pop downs in central parts of Spain. Two stages of rifting occurred in the east, one from Later Permian to Triassic, and the second from Late Jurassic to early Cretaceous. On the south side deposits of carbonates and clastic sediments formed a shelf in shallow water during late Triassic and Liassic times. This was rifted in Toarcian times (Early Jurassic 190 Ma).
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There are indications that the Bohemian Massif started moving northward from the Ordovician onward,Schätz et al. (2002) but many authors place the accretion of the Armorican terranes with the southern margin of Laurussia in the Carboniferous Hercynian orogeny (about 340 million years ago). The Rhenohercynian basin, a back-arc basin, formed at the southern margin of Euramerica just after the Caledonian orogeny. According to these authors, a small rim from Euramerica rifted off when this basin formed.
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Portion of North Africa that rifted to form Greater Adria The continent formed by rifting from the north Africa portion of the supercontinent of Gondwanaland 240 million years ago. It broke free into the Neo-Tethys Ocean and headed towards Laurasia. About 200 million years ago, the microcontinent of Iberia separated from the bulk of Greater Adria. The continent ended up accreting to the south Europe portion of the supercontinent of Laurasia, 140 million years ago.
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Animation of the rifting of Pangaea From 320 Ma onward, Gondwana, Laurussia, and intervening terranes merged to form the supercontinent Pangea. Pangea's main amalgamation occurred during the Carboniferous but continents continued to be added and rifted away in the Late Paleozoic to Early Mesozoic. Pangea ruptured during the Jurassic, preceded by and associated with widespread magmatic activity, including the Karoo flood basalts and related dyke swarms in South Africa and the Ferrar Province in East Antarctica.
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The initial rifting of Australia and Antarctica in the Jurassic continued through the Cretaceous, with offshore development of a mid ocean ridge seafloor spreading centre. Tasmania was rifted off during this stage. Cretaceous volcanism in the offshore of Queensland was related to a minor episode of arc formation, typified by the Whitsunday Islands, followed by development of offshore coral platforms, passive margin basins and far-field volcanism throughout the quiet Hunter- Bowen orogenic belt. Cretaceous sedimentation continued in the Surat Basin.
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The South Atlantic did not develop uniformly; rather, it rifted from south to north. Also, at the same time, Madagascar and India began to separate from Antarctica and moved northward, opening up the Indian Ocean. Madagascar and India separated from each other 100–90 Ma in the Late Cretaceous. India continued to move northward toward Eurasia at 15 centimeters (6 in) a year (a plate tectonic record), closing the eastern Tethys Ocean, while Madagascar stopped and became locked to the African Plate.
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Later, it was proposed that the Zenith Plateau, like the adjacent Wallaby Plateau, consists of a continental fragment of highly attenuated, stretched, and faulted continental crust that has been extensively intruded by magmatic rocks and deeply buried by volcanic rocks during the initial breakup of East Gondwana.Planke, S., P. A. Symonds, and C. Berndt, 2002, Volcanic rifted margin structure and development: A comparison between the NE Atlantic and western Australian continental margins. Paper no. 90022, AAPG Hedberg Conference, Stavanger, Norway, 8–11 Sept.
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The India Plate departed from the Gondwanaland and headed northwards at a rate of 10 cm/yr during the Cretaceous Period. The rifted Burma-microplate from Gondwanaland also docked against Shan-Thai block and together formed part of the Sunda plate approximately in the period. There is a discrepancy for the time of the Burma-Shan-Thai collision: Mitchell (1989) says Early Cretaceous yet changes to Mid-Eocene in 1993; Hutchison (1989) says Late Cretaceous; and Acharyya (1998) says late Oligocene.
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The Farallon Basin is a submarine depression located on the seabed at the southern end of the Gulf of California. The basin results from the activity of one of the several spreading centers in the Gulf. The basin is linked to the Atl Fault to the south, and the Farallon Fault in the north. The Farallon Basin has a spreading axis at its center, so the seafloor here is oceanic crust, transitioning into thin, rifted continental crust at the basin's edges.
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North China docked with Mongolia and Siberia during the Carboniferous–Permian, followed by South China. The Cimmerian blocks then rifted from Gondwana to form the Palaeo- Thethys and Neo-Tethys oceans in the Late Carboniferous, and docked with Asia during the Triassic and Jurassic. Western Pangaea began to rift while the eastern end was still being assembled. The formation of Pangaea and its mountains had a tremendous impact on global climate and sea levels, which resulted in glaciations and continent-wide sedimentation.
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The Indian subcontinent, or the South Asian subcontinent, sometimes simply called the subcontinent, is a physiographical region in southern Asia, situated on the Indian Plate and projecting southwards into the Indian Ocean from the Himalayas. The region is dominated by the Deccan Peninsula (aka the Indian Peninsula), which occupies approx. 48.6% of the total area of the subcontinent. Geologically, the Indian subcontinent is related to the landmass that rifted from Gondwana and merged with the Eurasian landmass nearly 55 million years ago.
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South China rifted away from the Gondwana supercontinent in the Silurian. During the formation of the great supercontinent Pangaea, South China was a smaller, separate continent located off the east coast of the supercontinent and drifting northward. In the Triassic the Yangtze Plate collided with the North China Plate, thereby connecting with Pangaea, and formed the Sichuan basin. In the Cenozoic the Yangtze Plate was influenced by the collision of the Indian and Eurasian plates creating the uplifting of the Longmen Mountains.
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Gilbert Seamount is a large seamount in the Tasman Sea located west of the South Island of New Zealand at the southern edge of the Lord Howe Rise. It has an elongated northwest–southeast trend, covering an area of about and rising to below sea level. The seamount is a continental fragment that rifted away from the South Tasman Rise and Challenger Plateau during the Cretaceous breakup of Gondwana. It is separated from the easterly Challenger Plateau by a deep saddle.
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The South Pandora and Tripartite Ridges in the northern NFB are active spreading ridges with -long segments, a -wide volcanic axis, and ordered magnetic lineations running parallel to the ridge. The ridge segments are separated by complex relay zones rather than transform faults. The South Pandora Ridge is divided into five segments averaging in width. The axial valley is partly obscured by faulted and rifted volcanic structures; elongated grabens are typical of slow spreading ridges with steep walls flanking a deep valley.
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The platform's basement rocks include Precambrian- Cambrian igneous rocks, Ordovician-Devonian sedimentary rocks, and Triassic- Jurassic volcanic rocks.Arthur, J. D., 1988, Petrogenesis of Early Mesozoic tholeiite in the Florida basement and overview of Florida basement geology: Florida Geological Survey Report of Investigation 97, 39 p. Florida's igneous and sedimentary foundation separated from what is now the African Plate when the super-continent Pangea rifted apart in the Triassic and possibly pre- Middle Jurassic. It then secured to the North American craton.
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By the middle Carboniferous, however, South China had already been in contact with North China long enough to allow floral exchange between the two continents. The Cimmerian blocks rifted from Gondwana in the Late Carboniferous. In the early Permian, the Neo-Tethys Ocean opened behind the Cimmerian terranes (Sibumasu, Qiantang, Lhasa) and, in the late Carboniferous, the Palaeo-Tethys Ocean closed in front. The eastern branch of the Palaeo-Tethys Ocean, however, remained opened while Siberia was added to Laurussia and Gondwana collided with Laurasia.
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Prior to the onset of orogeny the Archean-aged craton of what is today northeastern Fennoscandia rifted creating an ocean basin, the "pre-Svecofennian Ocean", that then closed during the Svecofennian orogeny. The closure of this basin was indebted to subduction and resulted thus both in the formation of igneous rocks and the emplacement of the Jormua and Outokumpu ophiolites about 1950 million years ago. In the later stages of the Lapland-Savo orogeny an island arc, the Knaften arc, accreted to the Keitele-Karelia-Norrbotten collage.
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In Japan the main technology base is a part of the country that was "rifted" from Earth's past. The technology, regardless of the unlikelihood of the varied factions obtaining it, is in fact instrumental to the continued survival of mankind in a world where many creatures now can survive being struck by the main gun of a battle tank. The most prolific weapons on Rifts Earth, in nearly all regions, are energy weapons. The most common are lasers, ion beams, plasma cannons, and particle beams.
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Late Carboniferous to Early Permian deposits of Tethyan affinity in the Zanskar-Spiti area are mostly terrigenous, detrital sedimentary rocks, although some magmatic activity documented in Pakistan and central Nepal has been associated with this period. These sedimentary layers are associated with the erosion that followed the uplift of the margins of the newly rifted Indian continent. In the eastern and central Himalayas more voluminous volcanic eruptions have been documented from the same period. The Abor volcanics produced of basaltic to andesitic flows and tuffs.
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It is believed, for instance, that the event happened some 300 million years ago, in the Palaeozoic. At that time, Australia lay quite a long way south of where it now lies. It had not yet rifted apart from Antarctica; both continents, and others, were joined together as parts of Gondwana. The theoretical asteroid itself is reckoned to have measured ten kilometres across, and when it struck, the energy that it released was equivalent to 650 million Hiroshima A-bombs (and thus roughly 41 zettajoules).
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Off to the west were three other masses: Laurentia, Siberia and Baltica, located as if on the vertices of a triangle. To the south of them was a large archipelago, the terrane Avalonia, rifted off the north Gondwana margin in early Ordovician. By the end of the Silurian and in Early Devonian times, Baltica and Laurentia drifted towards each other, closing the Iapetus Ocean between them. They collided in the Caledonian orogeny and formed the Caledonide mountains of North America, Greenland, the British Isles and Norway.
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The remains of the Farallon Plate are the Juan de Fuca, Explorer and Gorda Plates, subducting under the northern part of the North American Plate; the Cocos Plate subducting under Central America; and the Nazca Plate subducting under the South American Plate. The Farallon Plate is also responsible for transporting old island arcs and various fragments of continental crustal material rifted off from other distant plates and accreting them to the North American Plate. These fragments from elsewhere are called terranes (sometimes, "exotic" terranes). Much of western North America is composed of these accreted terranes.
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Basin formation was initiated in the middle Eocene as extension related to the opening of the Makassar straits and Celebes Sea rifted the crust of Eastern Borneo. This rifting created a broad system of half grabens that reverse polarity along NNE-SSW and N-S trending normal faults. Thermal subsidence in the late Eocene and early Oligocene induced minor reactivation along the existing faults. During the late Oligocene there was a brief renewal of extension and rifting along the northern margin of the basin, while the other basin margins experienced uplift.
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Final breakup formed a large group of mafic dike and sill swarms in the North American provinces 2.2–2.1 billion years ago. By the Paleoproterozoic era Kenorland had already rifted apart, and the TGB formed a small part of the supercontinent Columbia starting 1.9–1.8 billion years ago. Eastern India, Australia, Laurentia, Baltica, North China, the Amazon shield and portions of Antarctica formed the landmass until it ruptured 1.5–1.4 billion years ago. In the late Mesoproterozoic era 1.1 billion years ago, the Temagami belt was part of another supercontinent.
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The Kelabit Highlands is thought to developed from the rifted continental crust where water sediments were deposited before Borneo was separated from the mainland Eurasian plate. This is evidenced by the presence of evaporite and limestone found in the area. Evidence of folding and faulting along the NE-SW axis is also found in this area. The types of stones changes from oxidised iron and coal-bearing sandstones in the east of Kelabit highlands, to mudstone and limestone of the Kelabit highlands, and grey sandsones westwards in the Mount Murud region.
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During the Karoo period, southern Gondwana rifted across a large area encompassing what is now southern South America and South Africa. The rift basin and surrounding regions were cloaked in thick layers of continental sediment and sedimentation accelerated when Gondwana drifted over the South Pole, causing massive glaciation of Africa in the Karoo Ice Age. Ultimately, the glaciers melted at the end of the Permian, creating a swampy delta environment. Rocks directly preserving this sequence are found in the Karoo Supergroup, one of the most extensive stratigraphic units in southern Africa.
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Mostly mountainous, the region arose through faults resulting from the Rift Valley. Geologically, the Horn and Yemen once formed a single landmass around 18 million years ago, before the Gulf of Aden rifted and separated the Horn region from the Arabian Peninsula. The Somali Plate is bounded on the west by the East African Rift, which stretches south from the triple junction in the Afar Depression, and an undersea continuation of the rift extending southward offshore. The northern boundary is the Aden Ridge along the coast of Saudi Arabia.
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It is difficult to reconstruct the early wanderings of the West African Craton, but around 1.13–1.071 billion years ago it seems to have been one of the cratons that came together to form Rodinia, a supercontinent. At that time, the Congo Craton lay to the west of the Amazonian Craton, and the West African Craton lay to the south where both were rotated about 180° and retain this relative configuration. Around 750 million years ago Rodinia rifted apart into three continents: Proto-Laurasia, the Congo craton and Proto-Gondwana.
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Danube Planum as seen by Voyager 1 in March 1979 Danube Planum is a rifted mesa on the surface of Jupiter's moon Io. It is located on Io's trailing hemisphere at . Danube Planum is 244.22 kilometers across and 5.5 km tall. The mountain is bisected by a 15-to-25-kilometer-wide, northeast-southwest- trending canyon, splitting the mountain into two main east and west mountains, with several additional blocks at the southern end of the fracture. The outer margin of the plateau is marked by 2.6-to-3.4-km-tall scarps.
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The Otway Basin developed along the Australian Southern Rift System during late Jurassic to Cenozoic breakup of eastern Gondwana as Antarctica began rifting away from Australia. The basin lies at the transition from a normal-obliquely rifted continental margin to the west to a transform continental margin to the southeast. This transition zone is dominated by transtensional faulting that contributes to the basin's complex structural and depositional history. The margin developed through repeated episodes of extension and thermal subsidence leading up to, and following, the commencement of seafloor spreading between Australian and Antarctica.
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In Northern Hainan, there is a prominent fault, the Changjiang-Qionghai fault, along which shows the traces where the oceanic basin rifted apart under consistent extension in Late Paleozoic. The Cambrian and Permian units were then deposited in the basin. Also, it is suggested that from the Late Devonian to Permian, Hainan Island as part of the South China Block drifted towards the Southeast Asian crustal plate in the north, breaking away from the East Gondwana. As a result, there was an unconformity between the Paleozoic and the Mesozoic units.
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The Jurassic () was important in the development of birds, one of the insects' major predators. During the early Jurassic period, the supercontinent Pangaea broke up into the northern supercontinent Laurasia and the southern supercontinent Gondwana; the Gulf of Mexico opened in the new rift between North America and what is now Mexico's Yucatan Peninsula. The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous Period, when Gondwana itself rifted apart. The global climate during the Jurassic was warm and humid.
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Bathymetric data suggest it is a possible graben structure with steep, linear, north-south margins that formed during the Eurekan Rifting Episode. The faults forming the supposed graben appear to have been guided in part by the structure of the Cornwallis Fold Belt, but probably were controlled ultimately by trends in the Precambrian crystalline basement. The Kaltag Fault is a northeast trending structure that extends along the continental margin northwest of the Queen Elizabeth Islands. It forms a boundary between the Canadian Arctic Rift System and other rifted structures to the northwest.
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Extending through northern North America is a major seaway system connecting the Atlantic and Arctic oceans. This system was created by geological events of the Canadian Arctic Rift System and is still controlled by rift structures. It includes the Northwest Passage, which cuts through the Labrador Sea, Baffin Bay, Parry Channel and other channels within and adjacent to the Arctic Archipelago. Inflow from the Atlantic Ocean and outflow from the Arctic Ocean has resulted in ocean currents flowing along the rifted continental margins of West Greenland, Baffin Island and Labrador.
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The geology of Turks and Caicos includes the Turks and Caicos Bank, which together with the Florida-Bahamas Platform is a section of continental crust rifted away from North America during the rifting open of the Atlantic Ocean. Triassic sedimentary and volcanic rocks are inferred based on similar rocks in the Bahamas, overlain by Jurassic, Cretaceous and Paleogene limestone. During a drop in sea level during the Pleistocene glaciations, limestone was exposed as plateaus as sand dunes accumulated atop them and a karst landscape developed with caves and blue holes.
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The Alexander terrane is made up of Cambrian-Ordovician quartz sandstone, limestone and mafic volcanic rocks, Ordovician-Silurian carbonates, siltstone and calcareous mudstone, as well as Devonian-Triassic siltstone, sandstone and carbonate. Geologists have subdivided the Alexander terrane into the Saint Elias subterrane in the Yukon and British Columbia (the Craig subterrane is located in Alaska). Some have suggested that the two subterranes were rifted off of Baltica and then brought together during the Silurian-Devonian Klakas orogeny. The Wrangellia terrane linked with the Alexander is somewhat younger.
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During the Neoproterozoic, older parts of the Armorican Massif formed the northern margin of the paleocontinent Gondwana. During the Paleozoic era, the Armorican Massif was part of the microcontinent Armorica, which probably also included terranes found in the Vosges, Black Forest and Bohemian Massif further east. Armorica rifted off the northern margin of Gondwana somewhere during the Ordovician or Silurian periods to move northward and collide with Laurussia during the Hercynian orogeny. The oldest rocks of the massif are Neoproterozoic sediments of the Brioverian Supergroup which were deformed and metamorphosed during the Cadomian orogeny.
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Instead thrust faults generally cause a thickening of the stratigraphic section. When thrusts are developed in orogens formed in previously rifted margins, inversion of the buried paleo-rifts can induce the nucleation of thrust ramps. Foreland basin thrusts also usually observe the ramp-flat geometry, with thrusts propagating within units at a very low angle "flats" (at 1–5 degrees) and then moving up- section in steeper ramps (at 5–20 degrees) where they offset stratigraphic units. Thrusts have also been detected in cratonic settings, where "far- foreland" deformation has advanced into intracontinental areas.
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The Sirte Basin province is considered to be a type locality of a continental rift (extensional) area and is referred to as part of the Tethyan rift system.Futyan (1996) According to the designation scheme of Bally and Snelson, it is classified as 1211; a cratonic basin located on earlier rifted grabens on a rigid lithosphere and not associated with formation of megasutures.A. Bally and S. Snelson (1980) p.9 Clifford terms it as an interior fracture basin near the tectonic plate margin, which characteristically has an axis at an angle to that margin.
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The Jurassic Period extends from about 201.3 ± 0.2 to 145.0 Ma. During the early Jurassic, the supercontinent Pangaea broke up into the northern supercontinent Laurasia and the southern supercontinent Gondwana; the Gulf of Mexico opened in the new rift between North America and what is now Mexico's Yucatan Peninsula. The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous Period, when Gondwana itself rifted apart. The Tethys Sea closed, and the Neotethys basin appeared. Climates were warm, with no evidence of glaciation.
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The Lord Howe Rise was formed by seafloor spreading which also resulted in the creation of the Tasman Sea. It was rifted away from Eastern Australia by a mid-ocean ridge that was active from 80 to 60 million years ago, and now lies 800 kilometres offshore from mainland Australia. The Lord Howe Rise contains a line of seamounts called the Lord Howe Seamount Chain which formed during the Miocene period when this part of Zealandia existed over the Lord Howe hotspot. Lord Howe was the last volcano to erupt on the rise.
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The existence of the South China Sea slope also leads the strike of impinging folds with NNW-trend to turn more sharply to a NE-strike, parallel to strike of the South China Sea slope. Analysis shows that the pre-orogenic mechanical/crustal heterogeneities and seafloor morphology exert strong controls on the thrust-belt development in the incipient Taiwan arc-continent collision zone.Lin, Andrew T. et al. Tectonic Features Associated with the Overriding of an Accretionary Wedge on top of a Rifted Continental Margin: An Example from Taiwan.
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In the Paleocene, Borneo was a promontory of SE Asia, partially separated by oceanic crust of the proto-South China Sea. There is geologic evidence that suggests Borneo has rotated counter clock wise about 45° from its orentation at the end of the Oligocene while remaining to straddle the equator. This would indicate most of the Paleogene sediment in North Borneo was sourced from Indochina. In the Mid Eocene formation of the Celebs Sea and Makassar Strait rifted the eastern margin of Borneo while subduction of oceanic crust occurred on the western margin, producing deep basins on both sides.
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This necessitates drilling to depths of greater than in order to tap the temperatures of more than . The drilling is at a rifted plate margin on the mid-oceanic ridge. Producing steam from a well in a reservoir hotter than —at a proposed rate of around should be sufficient to generate around 45 MW. If this is correct, then the project could be a major step towards developing high-temperature geothermal resources. "Deep Vision" recognized at its inception that much research would be needed regarding the poorly understood supercritical environment and as such sought to promote inclusion of the wider scientific community.
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Collision began along the Great Lakes tectonic zone with the Algoman mountain-building event and continued for tens of millions of years. During the formation of the GLTZ, the gneissic Minnesota River Valley subprovince was thrust up onto the Superior province's edge as it consumed the Superior province's oceanic crust. Fragmentation of the Kenorland supercontinent began and was completed by . The Wyoming province is the continental landmass that is hypothesized to have rifted away from the southern Superior province portion of Kenorland, before moving rapidly west and docking with the Laurentia supercontinent 1,850 to 1,715 million years ago.
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Sunset on the South China Sea off Mũi Né village on the south-east coast of Vietnam The sea lies above a drowned continental shelf; during recent ice ages global sea level was hundreds of metres lower, and Borneo was part of the Asian mainland. The South China Sea opened around 45 million years ago when the "Dangerous Ground" rifted away from southern China. Extension culminated in seafloor spreading around 30 million years ago, a process that propagated to the SW resulting in the V-shaped basin we see today. Extension ceased around 17 million years ago.
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Geography of the Permian world During the Permian, all the Earth's major landmasses were collected into a single supercontinent known as Pangaea. Pangaea straddled the equator and extended toward the poles, with a corresponding effect on ocean currents in the single great ocean ("Panthalassa", the "universal sea"), and the Paleo-Tethys Ocean, a large ocean that existed between Asia and Gondwana. The Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, causing the Paleo- Tethys Ocean to shrink. A new ocean was growing on its southern end, the Tethys Ocean, an ocean that would dominate much of the Mesozoic era.
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Precambrian rocks from the Iberian Peninsula suggest it too probably formed part of core Gondwana before its detachment as an orocline in the Variscan orogeny close to the Carboniferous–Permian boundary. South-east Asia is made of Gondwanan and Cathaysian continental fragments that were assembled during the Mid-Palaeozoic and Cenozoic. This process can be divided into three phases of rifting along Gondwana's northern margin: firstly, in the Devonian, North and South China, together with Tarim and Quidam (north-western China) rifted, opening the Palaeo-Tethys behind them. These terranes accreted to Asia during Late Devonian and Permian.
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These horsts and grabens extend from onshore areas northward into a complex offshore terrane that includes the Ionian Sea abyssal plain to the northeast. This plain is underlain by oceanic crust that is being subducted to the north and east beneath the Hellenic arc. The Pelagian province to the west, particularly the pull-apart basins of the Sabratah Basin and extending along the South Cyrenaica Fault Zone (SCFZ) and the Cyrenaica Platform to the east, is strongly influenced by extensional dextral strike-slip faulting. To the south, the Nubian Swell is the stable continental basement for this rifted basin.
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During the middle of the Miocene period Japan was affected by the opening of the Sea of Japan as a back-arc basin in response to continuing subduction of the Pacific Plate. This period of extensional tectonics caused the development of rift basins on the western side of Honshu, including the northern part of the Fossa Magna. When the back-arc spreading stopped during the late Miocene, the rifted area started to shorten and the basins became inverted. The western margin of the Nagano Basin, part of the Fossa Magna, is formed by an active reverse fault zone, the West Nagano Basin Fault.
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Geothermal heating peaks in crust about to be rifted; and since warmer rocks are less dense, the crustal rocks rise up relative to their surroundings. This rising creates areas of higher altitude, where the air is cooler and ice is less likely to melt with changes in season, and it may explain the evidence of abundant glaciation in the Ediacaran period. The eventual rifting of the continents created new oceans and seafloor spreading, which produces warmer, less dense oceanic lithosphere. Due to its lower density, hot oceanic lithosphere will not lie as deep as old, cool oceanic lithosphere.
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In the Late Permian (Sakmarian-Roadian) the theoliitic Nar-Tsum(?) produced of spilites and Bhote Kosi basalts in southern Tibet. The slightly younger (Artinskian- Kazanian) Panjal Traps produced the largest magmatic province in north-western India. Its lava flows now covers 105 km2, from the eastern Zanskar-Spliti- Lahaul area to north-eastern Pakistan and they filled a rifted valley called the Zanskar-Spiti synclinorium. The original extent of the Panjal Traps may have exceeded 0.2x106 km2, a distribution similar to those of the Emeishan LIP in south-western China and the Columbia River basalts in north-western United States.
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The Burwash Basin consists of turbidites interbedded with felsic to indermediate volcanic tuff. At 2634 Ma the Slave switched to a compressional regime and the Burwash Basin started to close, possibly due to shallow subduction from the NW or SE. By 2.6 Ga the Slave had collided with the much larger Sclavia, resulting in shortening and cross-folding over the craton. The presence of three rifted margins around the Slave, as well as similarly aged 3.3–3.5 Ga basement rocks, fuchsitic quartzite, and 2.9 Ga tonalites, suggest that the Dharwar, Zimbabwe, and Wyoming cratons were also part of Sclavia.
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The region probably formed far south-west of its present location where it was subsequently rifted apart when the South Fiji Basin opened in the Early Oligocene. From the Early Oligocene to Miocene the region was part of an arc that formed the northern margin of the Australian plate. The NFB back-arc basin broke through this margin 12 and has since the Late Miocene rotated the New Hebrides Arc 30° clockwise and Fiji at least 100° counter-clockwise. Today the Pacific Plate is subducting westward along the eastern margin of the NFB, the Tonga-Kermadec Trench.
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The three largest plateaus, the Caribbean, Ontong Java, and Mid-Pacific Mountains, are located on thermal swells. Other oceanic plateaus, however, are made of rifted continental crust, for example the Falkland Plateau, Lord Howe Rise, and parts of Kerguelen, Seychelles, and Arctic ridges. Plateaus formed by large igneous provinces were formed by the equivalent of continental flood basalts such as the Deccan Traps in India and the Snake River Plain in the United States. In contrast to continental flood basalts, most igneous oceanic plateaus erupt through young and thin () mafic or ultra-mafic crust and are therefore uncontaminated by felsic crust and representative for their mantle sources.
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Avalonian terranes that constitute Avalonia are the following modern-day regions: northern France, Belgium (the Ardennes), England, Wales, southeastern Ireland, eastern Newfoundland, Nova Scotia, southern New Brunswick and some coastal parts of New England. The basement consisted of Late Precambrian age arc rocks, and is believed to come from the margin of Gondwana, sometime in the Early Ordovician. Avalonia rifted from Gondwana, during the onset of igneous activity in the Ardennes, Wales, and SE Ireland that consumed the Tornquist Sea oceanic crust. It drifted in a northerly direction and probably collided with Baltica in the Late Ordovician, and then with Laurentia in the Late Devonian.
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As Zealandia had rifted away at this time it explains the lack of ground dwelling marsupials and placental mammals in New Zealand's fossil record. Dinosaurs continued to prosper but, as the angiosperms diversified, conifers, bennettitaleans and pentoxylaleans disappeared from Gondwana 115 Ma together with the specialised herbivorous ornithischians, whilst generalist browsers, such as several families of sauropodomorph Saurischia, prevailed. The Cretaceous–Paleogene extinction event killed off all dinosaurs except birds, but plant evolution in Gondwana was hardly affected. Gondwanatheria is an extinct group of non-therian mammals with a Gondwanan distribution (South America, Africa, Madagascar, India, and Antarctica) during the Late Cretaceous and Palaeogene.
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In the Precambrian, when the Arctic was located south of the Equator, the continent Arctica (or Arctida) filled the gap between the cratons that today surround the Arctic region. Arctica rifted apart in the Late Precambrian (950 Ma) and was reassembled in a new configuration in the Late Paleozoic (255 Ma). Cape Tegethoff, a basaltic headland of Franz Josef Land During the Jurassic- Cretaceous this second continent, known as Pangea, broke apart, opening the Amerasian Basin and the Arctic Ocean. HALIP dispersed the components of this second continent around the margins of the Arctic Ocean where they are now terranes and microplates embedded into fold belts or overlain by sediments.
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Plate reconstruction during the late Devonian, showing the location of Armorica (Am) within the proposed Hun superterrane Geological map of the Armorican Massif, the main outcrop of the Armorican 250px The Armorican terrane, Armorican terrane assemblage, or simply Armorica, was a microcontinent or group of continental fragments that rifted away from Gondwana towards the end of the Silurian and collided with Laurussia towards the end of the Carboniferous during the Variscan orogeny. The name is taken from Armorica, the Gaulish name for a large part of northwestern France that includes Brittany, as this matches closely to the present location of the rock units that form the main part of this terrane.
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Rift episodes were followed by initiation of sea-floor spreading first to the south, then to the east, and finally to the northeast of the Grand Banks area. Widely faulted and moderately rotated Upper Triassic to Lower Cretaceous beds within the rift basin were subsequently buried beneath a relatively unstructured cover of Upper Cretaceous and Tertiary strata. These latter minimally deformed strata were deposited on the newly established passive margin. The current passive margin conditions were established when the last rifted border to the three-sided promontory of continental crust underlying the Grand Banks bathymetric feature formed along its northeast margin near the start of Late Cretaceous times.
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Dragon Cliffs of the Strand Fiord Formation The Sverdrup Basin Magmatic Province is a large igneous province located on Axel Heiberg Island and Ellesmere Island, Nunavut, Canada near the rifted margin of the Arctic Ocean at the end of Alpha Ridge. With an area of 550,110 km2, the Sverdrup Basin Magmatic Province forms part of the larger High Arctic Large Igneous Province and consists of flood basalts, dikes and sills which form two volcanic formations called the Ellesmere Island Volcanics and Strand Fiord Formation. The flood basalt lava flows are similar to those of the Columbia River Basalt Group in the U.S. states of Washington, Oregon and Idaho.
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Due east of the Baja California Peninsula, the Rise is sometimes referred to as the Gulf of California Rift Zone. In this area, newly formed oceanic crust is intermingled with rifted continental crust originating from the North American Plate. Near Easter Island, the East Pacific Rise meets the Chile Rise at the Easter Island and Juan Fernandez microplates, trending off to the east where it subducts under the South American Plate at the Peru–Chile Trench along the coast of southern Chile. The southern extension of the East Pacific Rise (called the Pacific- Antarctic Ridge) merges with the Southeast Indian Ridge at the Macquarie Triple Junction south of New Zealand.
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The Adare Trough is a single, northwest-southeast trending, graben roughly 120 km long with high rifted flanks located centrally in the Adare Basin, 100 km northwest of Cape Adare. The flanks are roughly 40 km apart and are asymmetrical when compared to one another, with the East flank rising higher than the west by roughly 550 meters. The major uplift required to form the Adare trough marks the last major extensional phase of the Adare basin. Magnetic anomalies curve southwards from the Adare Trough towards the Ross Sea, indicating the Adare Trough is part of the extinct third arm of a West Antarctic Rift System ridge- ridge-ridge triple junction.
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Various models have Siletzia forming inshore, on or near the continental margin. While all current models have Siletzia rifting away from the continent after accretion or formation, a subclass of "rifted" models consider the rifting to have caused the Siletzia eruptions. proposed that the Siletzia basalts might have "leaked" through transform faults (perpendicular to a spreading ridge) during changes in direction of the tectonic plates. The size of these eruptions and their location in this region is attributed to proximity to the Yellowstone hotspot.. This "leaky transform" theory seems to be largely rejected, likely because the plate motion model it was based on was shown to be faulty.. Wells, et al.
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The Shan–Thai or Sibumasu Terrane is a mass of continental crust extending from Tibet into Southeast Asia sharing a similar geological history. The Shan–Thai Terrane rifted from Australia in the Permian and collided with the Indochina terrane in the Triassic.: "Thailand consists of Shan-Thai and Indochina Microcontinents or Terranes welded together by the subsequently deformed Nan Suture.... During the Middle Triassic Shan–Thai sutured nearly simultaneously to Indochina and to South China, the continent-continent collision being a part of the Indosinian Orogeny and Indochina tended to underthrust Shan–Thai." It extends from Malaysia, through peninsular Thailand, Myanmar, West Yunnan, to Lhasa.
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The volcanism began in northern Madagascar and moved toward southern Madagascar over a period of several million years. While age constraints on the flood basalts vary depending on the source, most concur that the volcanism occurred between 85 to 92 Ma using argon-argon dating processes. In northern Madagascar, ages ranged from 88 to 92 Ma, while in southern Madagascar, ages ranged from 85 to 88 Ma. Argon-argon and uranium-lead dating both indicate that the volcanism first ended in the northern part of the island. The extent of the volcanism covers the rifted margin of the eastern coast of Madagascar, the Mahajanga and Morondava basins in western Madagascar.
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The Hindu Kush photographed by Apollo 9 Geologically, the range is rooted in the formation of a subcontinent from a region of Gondwana that drifted away from East Africa about 160 million years ago, around the Middle Jurassic period. The Indian subcontinent, Australia and islands of the Indian Ocean rifted further, drifting northeastwards, with the Indian subcontinent colliding with the Eurasian Plate nearly 55 million years ago, towards the end of Palaeocene. This collision created the Himalayas, including the Hindu Kush. The Hindu Kush are a part of the "young Eurasian mountain range consisting of metamorphic rocks such as schist, gneiss and marble, as well as of intrusives such as granite, diorite of different age and size".
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There is a parking lot at this entrance, a picnic area, and the start of the preserve's main path which stretches about a half mile along the east side of Haledon Reservoir. A few small, unmarked trails extend west off the main path, leading to the shore of the reservoir and part of the system of dikes extending out into the water. The main path also runs through a few areas of exposed volcanic basalt, lava that erupted to the surface 200 million years ago as the super continent Pangaea rifted apart during the early Jurassic.Stanford, Scott D. OFM 54, Surficial Geology of the Paterson Quadrangle, Passaic, Bergen, and Essex Counties, New Jersey.
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The Pacific is ringed by many volcanoes and oceanic trenches Ulawun stratovolcano situated on the island of New Britain, Papua New Guinea The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth. The tectonic plates continue to move today. The slowest spreading ridge is the Gakkel Ridge on the Arctic Ocean floor, which spreads at less than , while the fastest, the East Pacific Rise near Easter Island, has a spreading rate of over .
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Microcontinents from the Cimmerian Superterrane, including Iran, collided with the Eurasian Plate by the late Triassic, while the Neo-Tethys oceanic crust subducated northwards under Eurasia. In the Sinai, the Triassic is preserved with open-ocean carbonate sediments and river sediments, as well as clastic material that spans into the Negev Desert. When the Cimmerian blocks dispersed in the Cretaceous, it caused rifting in the Afro-Arabian Plate area, continuing the expansion of the Palmyra and Levant basins. During the late Cretaceous and the start of the Cenozoic subsidence occurred in the rifted areas and the Levant Basin was part of the Messinian Salinity Crisis which left up to two kilometers of evaporate in the dried out Mediterranean region.
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On a broader scale, there was a change in absolute direction of the Pacific plate. (marked by the end of the bend in the Hawaiian-Emperor seamount chain), and a change in the convergence of the Kula plate with the North American plate.. As subduction waned so did the force that had clamped Siletzia against the continent, and the tectonic regime shifted from compressional to extensional.. Deposition of sand from the then proximal Idaho Batholith into the Tyee Formation in southern Oregon may have continued as late as 46.5 Ma,. but was interrupted when Siletzia rifted from the continent and began rotating away.As explained earlier, it appears the rotation was about a northern pole.
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The Permian extends from about 298.9 ± 0.15 to 252.17 ± 0.06 Ma. During the Permian all the Earth's major land masses, except portions of East Asia, were collected into a single supercontinent known as Pangaea. Pangaea straddled the equator and extended toward the poles, with a corresponding effect on ocean currents in the single great ocean (Panthalassa, the universal sea), and the Paleo-Tethys Ocean, a large ocean that was between Asia and Gondwana. The Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, causing the Paleo-Tethys to shrink. A new ocean was growing on its southern end, the Tethys Ocean, an ocean that would dominate much of the Mesozoic Era.
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Plate tectonics- 100 Ma, Cretaceous period The Cretaceous Period extends from circa to . During the Cretaceous, the late Paleozoic-early Mesozoic supercontinent of Pangaea completed its breakup into present day continents, although their positions were substantially different at the time. As the Atlantic Ocean widened, the convergent-margin orogenies that had begun during the Jurassic continued in the North American Cordillera, as the Nevadan orogeny was followed by the Sevier and Laramide orogenies. Though Gondwana was still intact in the beginning of the Cretaceous, Gondwana itself broke up as South America, Antarctica and Australia rifted away from Africa (though India and Madagascar remained attached to each other); thus, the South Atlantic and Indian Oceans were newly formed.
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Strength envelopes indicate that the rheological structure of the lithosphere underneath the foreland and the orogen are very different. The foreland basin typically shows a thermal and rheological structure similar to a rifted continental margin with three brittle layers above three ductile layers. The temperature underneath the orogen is much higher and thus greatly weakens the lithosphere. According to Zhou et al. (2003), “under compressional stress the lithosphere beneath the mountain range becomes ductile almost entirely, except a thin (about 6 km in the center) brittle layer near the surface and perhaps a thin brittle layer in the uppermost mantle.” This lithospheric weakening underneath the orogenic belt may in part cause the regional lithospheric flexure behavior.
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Idealized image showing the breakup of Gondwana as South America rifted away from Africa The breakup of Gondwana began in the early Cretaceous (about 184-132 Ma). South America began to drift westward from Africa as the South Atlantic Ocean opened, resulting in complete open marine conditions by 110 Ma. During this, the Owambo Basin was reactivated as a pull-apart rift basin pulling apart from the east to the west, but received compression from the opening of the Damara Belt to its south. This created rotational seismic wrench systems across the basin profile. These wrench systems allowed for intrusions of continental igneous deposits: sills and dikes, along with pegmatites from metasomatized country rock.
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Seafloor spreading to the south of Avalonia pushed the latter into north Laurentia and thrust up the northern Appalachian Mountains in the acadian phase of the Caledonian orogeny. Contemporaneously the Tornquist Sea between Avalonia and Baltica was entirely closed. Thus Avalonia formed the southern coast of the new continent Euramerica (Laurussia, the Old Red Sandstone continent in present-day North America, the British Isles, northern Germany, Scandinavia and western Russia). In late Devonian and in the Carboniferous the archipelago Armorica of southern Europe, which had rifted off Gondwana after Avalonia later in the Ordovician, was pushed into Avalonia, creating a second range, the North American/European Variscan, to the east of the Caledonide/Appalachian.
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The Permian () was a relatively short time period, during which all the Earth's major land masses were collected into a single supercontinent known as Pangaea. Pangaea straddled the equator and extended toward the poles, with a corresponding effect on ocean currents in the single great ocean ("Panthalassa", the "universal sea"), and the Paleo-Tethys Ocean, a large ocean that was between Asia and Gondwana. The Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, causing the Paleo- Tethys to shrink. At the end of the Permian, the biggest mass extinction in history occurred, collectively called the Permian–Triassic extinction event: 30% of all insect species became extinct; this is one of three known mass insect extinctions in Earth's history.
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The Cretaceous () had much of the same insect fauna as the Jurassic until much later on. During the Cretaceous, the late- Paleozoic-to-early-Mesozoic supercontinent of Pangaea completed its tectonic breakup into present day continents, although their positions were substantially different at the time. As the Atlantic Ocean widened, the convergent-margin orogenies that had begun during the Jurassic continued in the North American Cordillera, as the Nevadan orogeny was followed by the Sevier and Laramide orogenies. Though Gondwana was still intact in the beginning of the Cretaceous, it broke up as South America, Antarctica and Australia rifted away from Africa (though India and Madagascar remained attached to each other); thus, the South Atlantic and Indian Oceans were newly formed.
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Typically, accreting terranes are portions of continental crust which have rifted off another continental mass and been transported surrounded by oceanic crust, or they are old island arcs formed at some distant subduction zone. A tectonostratigraphic terrane is a fault-bounded package of rocks of at least regional extent characterized by a geologic history which differs from that of neighboring terranes. The basic characteristics of these terranes is that the present spatial relations are not compatible with the inferred geologic histories. Where terranes which lie next to each other possess strata of the same age, it must be demonstrable that the geologic evolutions are different and incompatible, and there must be an absence of intermediate lithofacies which could link the strata.
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Lhasa terrane approach to Qiangtang terrane More detailed view of the tectonic evolution of the Bangong suture zone The Lhasa terrane was formed from the North and South Lhasa terranes, which were at first separated by the Paleo-Tethys Ocean, and were joined in a suture zone in the Late Paleozoic. The Paleo-Tethys Ocean that separated the North and South Lhasa terranes closed, and around 260 Ma in the Late Permian an HP metamorphic belt formed between the two blocks. Around 220 Ma in the Triassic an MP metamorphic belt formed. The Tibetan Plateau was formed from a number of continental terranes that rifted from northern Gondwana in the Paleozoic and Mesozoic, moved northward and accreted to southern Asia.
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Despite their ardent anti-technology sentiments, one of the New Empire's closest allies is the Republic of Japan, an alliance centered on three pre-Rifts cities (Hiroshima, Iwakuni, and Kure) accidentally rifted off the planet at the exact moment of the Great Cataclysm, and sent hundreds of years into their future. The rest of the archipelago (which now has the pre-Rifts main island of Honshū divided into two islands from the risen sea levels) is dominated by smaller breakaway governments; a significant portion of the northern half of Japan is dominated by Oni and other denizens from Rifts called the Zone. Korea - both North and South - has been completely overrun by demons with nothing remaining of the pre-Rifts nations.
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Seeking to explain the observed clockwise paleorotation, and noting that Siletzia appeared to have rotated as a rigid block, proposed two models. First was rotation about a southern pivot in contact with the Klamath Mountains. This has various problems, especially because at the northern end sediments and even boulders from the continent are found at the base of the Crescent Formation, showing that it was near the continent from the beginning.. In the second model (subsequently refined by ), Siletzia was originally adjacent to the Olympic-Wallowa Lineament, then rifted from the continent and rotated about a northern pivot near the Olympic Peninsula. Because sediments also show the Klamaths in close contact from the start, this requires the Klamaths to have moved with Siletzia.
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From the Late Carboniferous to the Early Permian the New England orogen was dominated by an extensional setting related to a subduction to strike-slip transition. Subduction was re-initiated in the Permian and the granitic rocks of the New England Batholith were produced by a magmatic arc, indicating the presence of an active plate margin along most of the orogen. Permian to Cretaceous remains of this convergent margin, preserved as fragments in Zealandia (New Zealand, New Caledonia, and the Lord Howe Rise), were rifted off Australia during the Late Cretaceous to Early Tertiary break-up of eastern Gondwana and the opening of the Tasman Sea. The Cretaceous Junction Plate, located north of Australia, separated the eastern Tethys from Panthalassa.
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The banks of the South Scotia Ridge are made of continental crust that rifted off the land bridge 40-30 Ma. The banks on the northern Central Scotia Sea, on the other hand, are volcanic constructs overlaying an oceanic basement parts of which is the spreading centre of the separation between South America and Antarctica. Seafloor spreading in the West Scotia Sea continued until 6.6-5.9 Ma. The oldest volcanic activity in Central and Eastern Scotia Sea, i.e. the first signs of a volcanic arc, has been dated to 28.5 Ma. The South Sandwich Islands fore-arc originated in the Central Scotia Sea and was translated eastward by the back-arc spreading centre in the East Scotia Sea, i.e. the East Scotia Ridge.
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Geography of the Contiguous United States in the late Cretaceous period During the Cretaceous, the late-Paleozoic-to-early-Mesozoic supercontinent of Pangaea completed its tectonic breakup into the present-day continents, although their positions were substantially different at the time. As the Atlantic Ocean widened, the convergent-margin mountain building (orogenies) that had begun during the Jurassic continued in the North American Cordillera, as the Nevadan orogeny was followed by the Sevier and Laramide orogenies. Though Gondwana was still intact in the beginning of the Cretaceous, it broke up as South America, Antarctica and Australia rifted away from Africa (though India and Madagascar remained attached to each other); thus, the South Atlantic and Indian Oceans were newly formed. Such active rifting lifted great undersea mountain chains along the welts, raising eustatic sea levels worldwide.
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The East Bull Lake intrusive suite, in the southern Superior province near Sudbury, Ontario, aligns spatially with the Blue Draw Metagabbro if the Superior and Wyoming cratons are restored to the Kenorland configuration proposed by Roscoe and Card (1993). These layered mafic intrusions are of similar thickness and identical age, and occur along a rifted belt. Recent paleomagnetic and geochronological data from the central Wyoming craton support the hypothesis that the Huronian (in southern Ontario) and Snowy Pass (in southeastern Wyoming) supergroups were adjacent to each other at and may have evolved as a single sedimentary rift basin between 2,450 and 2,100 million years ago. These Huronian and Snowy Pass sedimentary rocks are similar, each having 2,450- to 2,100-million-year-old epicratonic rifts succeeded by a 2,100- to 1,800-million-year-old passive sedimentary margins.
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Mike (Millard Filmore) Coffin is an American oceanographer who was born in 1955 in Maine. His research expertise encompasses massive volcanism on the seafloor, environmental effects of massive volcanism, plate tectonics, and rifted continental margins. Educated at Dartmouth College (AB) and Columbia University (MA, MPhil, PhD), he has pursued an international career in oceanography.POGO Profile Following university studies, he worked at Geoscience Australia (1985-1989), the University of Texas at Austin (1990-2001), the University of Tokyo (2001-2007), the Japan Agency for Marine- Earth Science and Technology (2002-2003), the UK’s University of Southampton and National Oceanography Centre (2007-2010), and the University of Tasmania (2011-present). He has also held visiting positions at Dartmouth College (1982), the University of Oslo (1992, 1996), Geoscience Australia (2000), France’s University of Strasbourg (2001), and the University of Hawaii (2002).
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The southern pivot seems to be largely abandoned, in part because various studies (e.g.: ; ; ) show most of the rotation was post-accretion. These classes of models have been classified as either "accreted" or "rifted," but this is inaccurate as inshore formation can still involve accretion, and all offshore accretion models using a northern pivot imply rifting. Studies of Siletzia's origins have generally focused on accounting for two principal observations: the large paleorotation (described above), and the voluminous output (over 50,000 cubic miles, exceeding the volume of most continental rift zones, and some flood basalt provinces).. Accounting for the observed volumes of basalt requires an enhanced magmatic source, for which most models invoke either the presence of the Yellowstone hotspot, or slab windows.. The latter would have resulted from the subduction of the Farallon—Kula (or possibly Farallon—Resurrection) spreading ridge.
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The archean basement had served as a rigid indentor which controlled the overall wedge shaped geometry of the orogen. Lithology of area shows that the base rocks of Aravalli are of Mewar Gneiss formed by high-grade regional metamorphic processes from preexisting formations that were originally sedimentary rock with earliest life form that were formed during the archean eon, these contain fossils of unicellular organism such as green algae and cyanobacteria in stromatolitic carbonate ocean reefs formed during the paleoproterozoic era. Sedimentary exhalative deposits of base metal sulfide ores formed extensively along several, long, linear zones in the Bhilwara aulacogen or produced local concentration in the rifted Aravalli continental margin, where rich stromatolitic phosphorites also formed. Tectonic evolution of the Aravalli Mountains shows Mewar Geniss rocks are overlain by Delhi Supergroup type of rocks that also have post-Aravalli intrusions.
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Now here stood a rock near the Tritonian > lake; and of his own device, or by the prompting of some god, he smote it > below with his foot; and the water gushed out in full flow. And he, leaning > both his hands and chest upon the ground, drank a huge draught from the > rifted rock, until, stooping like a beast of the field, he had satisfied his > mighty maw. > Thus she spake; and they gladly with joyful steps ran to the spot where > Aegle had pointed out to them the spring, until they reached it. And as when > earth-burrowing ants gather in swarms round a narrow cleft, or when flies > lighting upon a tiny drop of sweet honey cluster round with insatiate > eagerness; so at that time, huddled together, the Minyae thronged about the > spring from the rock.
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There are four different perspectives needed to classify passive margins: # map-view formation geometry (rifted, sheared, and transtensional), # nature of transitional crust (volcanic and non-volcanic), # whether the transitional crust represents a continuous change from normal continental to normal oceanic crust or this includes isolated rifts and stranded continental blocks (simple and complex), and # sedimentation (carbonate-dominated, clastic-dominated, or sediment starved). The first describes the relationship between rift orientation and plate motion, the second describes the nature of transitional crust, and the third describes post-rift sedimentation. All three perspectives need to be considered in describing a passive margin. In fact, passive margins are extremely long, and vary along their length in rift geometry, nature of transitional crust, and sediment supply; it is more appropriate to subdivide individual passive margins into segments on this basis and apply the threefold classification to each segment.
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Mosaic of images taken by Voyager 1 of Pele (above right of center) and its filamentary volcanic plume As Voyager 1 approached the Jupiter system in March 1979, it acquired numerous images of the planet and its four largest satellites, including Io. One of the most distinctive features of these distant images of Io was a large, elliptical, footprint-shaped ring on the satellite's trailing hemisphere (the side facing away from the direction of motion in a synchronously-rotating satellite like Io). During the encounter itself on March 5, 1979, Voyager 1 acquired high-resolution images of the footprint-shaped region. At the center of bow tie-shaped dark region in the middle of the ring was a depression partially filled with dark material, by in size. This depression, later found to be the source of the Pele volcano, is at the northern base of a rifted mountain later named Danube Planum.
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