Misplaced Pages

#680319

92-488: Laurentia, Avalonia , Baltica , and a series of smaller terranes , collided in the Caledonian orogeny c. 400 Ma to form Laurussia/ Euramerica . Laurussia/Euramerica then collided with Gondwana to form Pangaea. Kazakhstania and Siberia were then added to Pangaea 290–300 Ma to form Laurasia. Laurasia finally became an independent continental mass when Pangaea broke up into Gondwana and Laurasia. Laurentia,

184-761: A cold spot in the Proto-pacific. Baltica remained near Gondwana in southern latitudes into the Ordovician . Laurentia, Baltica, and Siberia remained connected to each other within the short-lived, Precambrian - Cambrian supercontinent Pannotia or Greater Gondwana. At this time a series of continental blocks – Peri-Gondwana – that now form part of Asia, the Cathaysian terranes – Indochina, North China, and South China – and Cimmerian terranes – Sibumasu , Qiangtang , Lhasa , Afghanistan, Iran, and Turkey – were still attached to

276-720: A supercontinent existed from the Neoproterozoic to Jurassic , to the Russia , Siberian , and North China cratons . This hypothesis suggests that subduction of orogens in the Central Asian Orogenic Belt started in the late Precambrian and the Orogenic Belt reached its highest altitude with the amalgamation of Tarim's passive margin and northern accretionary system until the end Permian and middle Triassic . This hypothesis states that

368-464: 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. It collided with the continents Baltica , then Laurentia , and finally with Gondwana, ending up in the interior of Pangea . When Pangea broke up, Avalonia's remains were divided by the rift which became

460-548: A geological history from later in the early Cambrian until the mid-Orodovician. Subduction evolved along the shores of Gondwana, which caused Avalonia to rift away and begin its northbound journey towards Baltica during late Cambrian and Early Ordovician. The Rheic Ocean opened behind the Avalonian microcontinents. This independent movement of Avalonia started from a latitude of about 60° South. The eastern end of Avalonia collided with Baltica at 30°S, an event which closed

552-764: A large embayment west of the Appalachians. By the Middle Devonian, these two provinces had been united into one and the closure of the Rheic Ocean finally united faunas across Laurussia. High plankton productivity from the Devonian-Carboniferous boundary resulted in anoxic events that left black shales in the basins of Laurentia. The subduction of the Iapetus Ocean resulted in the first contact between Laurussia and Gondwana in

644-569: A separate southern Asian continent. This continent collided 240–220 Mya with a northern continent – North China, Qinling, Qilian, Qaidam, Alex, and Tarim – along the Central China orogen to form a combined East Asian continent. The northern margins of the northern continent collided with Baltica and Siberia 310–250 Ma, and thus the formation of the East Asian continent marked Pangaea at its greatest extent. By this time,

736-728: A series of large back-arc basins . During the Ordovician, these basins evolved into a new ocean, the Rheic Ocean , which separated a series of terranes – Avalonia , Carolinia , and Armorica  – from Gondwana. Avalonia rifted from Gondwana in the Early Ordovician and collided with Baltica near the Ordovician–Silurian boundary (480–420 Mya). Baltica-Avalonia was then rotated and pushed north towards Laurentia. The collision between these continents closed

828-789: A single tectonic unit. Avalonia is the largest of the peri-Gondwanan terranes, a series of continental blocks that more or less simultaneously broke off the margins of the southern supercontinent Gondwana and therefore share an early Paleozoic marine fauna. They were pulled northward and eventually collided to form the Appalachian , Caledonide , and Variscan orogens . West Avalonia, in North America, stretches from New England to Atlantic Canada, and East Avalonia, in Europe, from southern Britain to Brabant. Other Peri-Gondwanan terranes, sometimes called "Greater Avalonia", include Carolina in

920-482: A southward younging direction, meaning that the rocks in the north are older than the rocks in the south. Cenozoic - Mesozoic sedimentary basins can be found at the eastern portion of the Central Asian Orogenic Belt while volcanic-plutonic rocks formed from the Paleozoic to Mesozoic can be found in the middle and western portion of the Orogenic Belt. It has an extensive granitoid development as around 60% of

1012-640: Is debated. Laurentia and Baltica first formed a continental mass known as Proto-Laurasia as part of the supercontinent Columbia which was assembled 2,100—1,800 Mya to encompass virtually all known Archaean continental blocks. Surviving sutures from this assembly are the Trans-Hudson orogen in Laurentia; Nagssugtoqidian orogen in Greenland; the Kola-Karelian (the northwest margin of

SECTION 10

#1732765946681

1104-479: Is located at the southwest of the Qinhe City, Xinjian , Northwest China, is considered as one of the most important high-quality copper and gold reserve in the Central Asian Orogenic Belt, with the deposit being hosted by the volcanic rocks formed during Middle Devonian . Since Central Asian Orogenic Belt has a complex tectonic setting, it is often being associated with different kinds of energy production in

1196-680: Is located between the East European craton and North China craton on the Northwest-Southeast direction, and between Siberian craton and Tarim craton on the Northeast-Southwest direction. The belt extends for approximately 2500 km in the East-West direction. The Central Asian Orogenic Belt has a long and complicated geological history. Through mapping, geologists concluded that the geological formation has

1288-523: Is located in the eastern portion of the belt, which is in Inner Mongolia , Mongolia , and southern Russia . The Kazakhstan orocline, which is located in the north of the Tarim craton and Karakum craton, as well as at the south-east of Baltica , is a bend of the Central Asian Orogenic Belt, which consists of broken fragments of continents formed in the late Paleozoic . In Precambrian time,

1380-420: Is poorly known, but, based on isotopic analyses , proto-Avalonia most likely evolved together with Carolina about 800 Ma from volcanic arcs far offshore from the supercontinent Rodinia , most likely outboard continental terranes of more obvious West African affinities, such as Cadomia and Iberia . About 650 Ma the Avalonian belt collided with Gondwana. Avalonia originally developed along

1472-621: Is preserved in the Central Asian Orogenic Belt , the largest orogen on Earth. North China, South China, Indochina, and Tarim broke off Gondwana during the Silurian-Devonian; Palaeo-Tethys opened behind them. Sibumasu and Qiantang and other Cimmerian continental fragments broke off in the Early Permian. Lhasa , West Burma , Sikuleh, southwest Sumatra, West Sulawesi, and parts of Borneo broke off during

1564-624: Is rich in mineral ores, including platinum , gold , silver and copper . The mines of these valuable metals can be found and explored according to the tectonic settings and the structures of the orogenic belt . For platinum , its associated minerals can be found in the dunite , a type of ultramafic intrusive igneous rock , from the Xiadong Alaskan complex. The platinum would usually appear as platinum-group element sulfide and sulfarsenide. It could also appear as inclusions of chromite and clinopyroxene or as interstitial grains in

1656-824: Is today the Gulf of Mexico to Nova Scotia, and in Africa and Europe, from Morocco to Greenland. By c.  83 Mya spreading had begun in the North Atlantic between the Rockall Plateau , a continental fragment sitting on top of the Eurasian Plate, and North America. By 56 Mya Greenland had become an independent plate, separated from North America by the Labrador Sea-Baffin Bay Rift . By 33 Mya spreading had ceased in

1748-582: The Acadian orogeny . In the Carboniferous , the new continent and another terrane, Armorica which included Iberia , drifted in from Gondwana, trapping Avalonia between it and the continent so adding Iberia/Armorica to Euramerica. This was followed up by the arrival of Gondwana. The effects of these collisions are seen in Europe as the Variscan folding . In North America it shows as later phases of

1840-615: The Altaids , is one of the world's largest Phanerozoic accretionary orogens , and thus a leading laboratory of geologically recent crustal growth. The orogenic belt is bounded by the East European Craton and the North China Craton in the Northwest-Southeast direction, as well as Siberia Craton and Tarim Craton in the Northeast-Southwest direction. It formed by ocean closures during Neoproterozoic to

1932-656: The Ardennes of Belgium and north-eastern France, north Germany, north-western Poland, south-eastern Ireland, and the south-western edge of the Iberian Peninsula . Part of the British-Belgian section formed an island in the Carboniferous, affecting the disposition of coalfields; this is known by names such as the ' London-Brabant Island '. Its bulk had an effect on the geological structure between

SECTION 20

#1732765946681

2024-726: The Atlantic Ocean . When the term "Avalon" was first coined by Canadian geologist Harold Williams in 1964, he included only Precambrian rocks in eastern Newfoundland. More than a decade later he extended the term to include all exotic rocks from Newfoundland down to Rhode Island. Since the introduction of the term terrane in the 1980s, Avalonia has been referred to as "platform", "composite terrane", "superterrane", "East" and "West Avalonia", and "Avalon sensu lato". "Avalonia" can thus refer exclusively to rocks in Newfoundland (Avalonia sensu stricto ), an assembly of terranes, or

2116-601: 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. 610-590 Mya) – both Laurentia and Baltica were located south of 30°S, with

2208-1018: The Svecokarelian/Svecofennian orogen ) and the Volhyn—Central Russia and Pachelma orogenies (across western Russia) in Baltica; and the Akitkan Orogen in Siberia. Additional Proterozoic crust was accreted 1,800—1,300 Mya, especially along the Laurentia—Greenland—Baltica margin. Laurentia and Baltica formed a coherent continental mass with southern Greenland and Labrador adjacent to the Arctic margin of Baltica. A magmatic arc extended from Laurentia through southern Greenland to northern Baltica. The breakup of Columbia began 1,600 Mya, including along

2300-875: The Tornquist Sea , during the Late Ordovician. In Avalonia, folding, faulting, and volcanism followed – as evidenced in the Welsh Borderland and the Taconic deformation in Laurentia ;– some or all of which are related to the collision. Plinian eruptions resulted from the subduction beneath Avalonia and produced thick layers of K-bentonite in southwestern Baltica, while the Millbrig eruptions occurred in Laurentia. This Late Ordovician magmatism peaked between 457 and 449 Ma. In

2392-701: The Turgai Sea separated Europe and Asia from the Middle Jurassic to the Oligocene and as this sea or strait dried out, a massive faunal interchange took place and the resulting extinction event in Europe is known as the Grande Coupure . The Coraciiformes (an order of birds including kingfishers) evolved in Laurasia. While this group now has a mostly tropical distribution, they originated in

2484-402: The accretion of paleo-Kazakhstan completed, meaning that materials were added to the paleo-Kazakhstan at a subduction zone. The subsequent Devonian and Carboniferous rocks deposited on paleo-Kazakhstan were mainly volcanic rocks formed from continental arcs . During Devonian to early Carboniferous , several unconformities were formed, together with the thrusting in the back of

2576-534: The carbonates and turbidites of the southern continents during Silurian to Carboniferous . In the late Paleozoic , these rocks were deformed in two phases. Some well-developed strike slip faults can be found in Kazakhstan. The geology of Tuva-Mongolia orocline can be divided into two major parts. One of which was formed in the Precambrian , while the other one consists of sedimentary rocks in

2668-530: The orogenic belt . The following table shows the locations of some of the ophiolites that can be found in the Central Asian Orogenic Belt and the related interpretation on the evolutionary history of the Central Asian Orogenic Belt Being an accretionary orogen , the geological evolutionary history of the Central Asian Orogenic Belt is highly complicated. There are two major evolutionary hypotheses that have been proposed. One of

2760-560: The sauropods , theropods , and ornithischians  – was similar to that of the crocodilians. East Asia remained isolated with endemic species including psittacosaurs (horned dinosaurs) and Ankylosauridae (club-tailed, armoured dinosaurs). Meanwhile, mammals slowly settled in Laurasia from Gondwana in the Triassic, the latter of which was the living area of their Permian ancestors . They split in two groups, with one returning to Gondwana (and stayed there after Pangaea split) while

2852-697: The subduction under the original southern end of the Kipchak arc. During the Late Carboniferous (318-303 Myr), Baltica and Siberia experienced right-lateral shearing , combined with compressional force, the entire Kazakhstan orocline became more tightly packed. Until the Early Permian (269-260 Myr), the Nurol basin, which is a stretched continental crust , was formed and alkaline magmatism occurred at its basement. Finally, during

Laurasia - Misplaced Pages Continue

2944-623: The Acadian orogeny. This was happening at around the Equator during the later Carboniferous, forming Pangaea with Avalonia near its centre but partially flooded by shallow sea. In the Jurassic , Pangaea split into Laurasia and Gondwana, with Avalonia as part of Laurasia. In the Cretaceous , Laurasia broke up into North America and Eurasia with Avalonia split between them. Iberia

3036-864: The Appalachian and the deep bedrock of Florida in North America, Oaxaquia and Yucatán in Mexico, and the Chortis Block in Central America. The North American terranes of Ganderia and Carolinia are sometimes grouped with Avalonia because they were transferred together across the Iapetus Ocean. Sometimes the Meguma terrane in Nova Scotia is also included. The Avalonian part of Great Britain almost exactly coincides with England and Wales. Elsewhere in Europe, parts of Avalonia are found in

3128-630: The Arctic in the late Eocene c. 35 Mya from where they diversified across Laurasia and farther south across the Equator. The placental mammal group of Laurasiatheria is named after Laurasia. In the Triassic–Early Jurassic (c. 200 Mya), the opening of the Central Atlantic Ocean was preceded by the formation of a series of large rift basins, such as the Newark Basin , between eastern North America, from what

3220-758: The Ardennes and the English Midlands by influencing the subsequent crustal folding resulting from the Variscan collision. In Canada, Avalonia comprises the Avalon Peninsula of southeast Newfoundland , southern New Brunswick , part of Nova Scotia , and Prince Edward Island . In the United States, Avalonia consists of northern coastal Maine , all of Rhode Island , and other sections of coastal New England . The basement of Avalonia

3312-445: The Balkhash-Yili volcanic belt , documenting the event of lateral accretion of the continental crust. The collision between paleo-Kazakhstan and Tarim occurred from the middle Carboniferous to the beginning of the Permian. The south-verging thrusts in the northern part of the South Tienshan consist of ophiolites, accreted high-grade metamorphic rocks, basalts and cherts formed in deep sea environments. These rocks were thrusted upon

3404-412: The Cadomian–Avalonian, Cathaysian, and Cimmerian terranes – broke away from Gondwana and began to drift north. Laurentia remained almost static near the Equator throughout the early Palaeozoic, separated from Baltica by the up to 3,000 km (1,900 mi)-wide Iapetus Ocean . In the Late Cambrian, the mid-ocean ridge in the Iapetus Ocean subducted beneath Gondwana which resulted in the opening of

3496-444: The Carboniferous–Permian Siberia, Kazakhstan, and Baltica collided in the Uralian orogeny to form Laurasia. The Palaezoic-Mesozoic transition was marked by the reorganisation of Earth's tectonic plates which resulted in the assembly of Pangaea, and eventually its break-up. Caused by the detachment of subducted mantle slabs, this reorganisation resulted in rising mantle plumes that produced large igneous provinces when they reached

3588-542: The Central Asian Orogenic Belt formed due to the accretion of multiple oceanic arcs and continental crusts , while another hypothesis proposed that it was produced by accumulating subduction-accretion complexes on a magmatic arc . The Central Asian Orogenic Belt is now one of the most researched orogenic belts in the world due to its high significance in researching continental accretion and ore formation. It contains plentiful natural resources, including mineral ores, oil and gas. These rich mineral resources explain why

3680-528: The Central Asian Orogenic Belt involved numerous subduction , collision in parallel orientation, accretion , amalgamation of microcontinents and bending of oroclines . It is still debated whether the microcontinents derived from Gondwana were involved in the formation of the Central Asian Orogenic Belt in this hypothesis since the original structure of the Orogenic Belt is highly deformed and broken through tectonic evolution. The second hypothesis proposed by geologist Celal Sengor in 1993 suggested that

3772-482: The Central Asian Orogenic Belt is also called the Central Asian metallogenic domain, which is one of the largest metallogenic domains in the world. Like any typical accretionary orogen, the Central Asian Orogenic Belt is long and wide. It occupies roughly 30% of the land surface area of the entire Asia . It is located within the boundary of six nations, which are China , Kazakhstan , Kyrgyzstan , Mongolia , Russia , and Uzbekistan . The Central Asian Orogenic Belt

Laurasia - Misplaced Pages Continue

3864-446: The Central Asian Orogenic Belt to be one of the most important juvenile crust formations since the end of the Proterozoic . However, some geologists suggested that the extent of juvenile crust formed during the Paleozoic is highly overestimated as many of the Phanerozoic granites found in the belt were initially formed in the Mesoproterozic and being reworked later on. Collision of microcontinents and subduction happened at

3956-655: The Central Asian Orogenic Belt was formed due to the accumulation of Paleozoic subduction-accretion materials against a single magmatic arc. The entire process of the formation of Central Asian Orogenic Belt is explained below and summarized in Table 2 and Figure 5. This hypothesis suggests that Baltica craton was attached with Siberia craton during the period Ediacaran . Their locations during Ediacaran were confirmed from paleomagnetic data. Continental rifting between Baltica and Siberia happened from late Ediacaran to Cambrian (610-520 Myr ). During this period, collision of microcontinents and subduction happened at

4048-439: The Devonian a narrow seaway formed a barrier where the North Atlantic would later open. Tetrapods evolved from fish in the Late Devonian, with the oldest known fossils from Greenland. Low sea-levels during the Early Devonian produced natural barriers in Laurussia which resulted in provincialism within the benthic fauna. In Laurentia the Transcontinental Arch divided brachiopods into two provinces, with one of them confined to

4140-402: The Early Cretaceous c. 130 Mya in competition with faster growing flowering plants . Pines adapted to cold and arid climates in environments where the growing season was shorter or wildfire common; this evolution limited pine range to between 31° and 50° north and resulted in a split into two subgenera: Strobus adapted to stressful environments and Pinus to fire-prone landscapes. By

4232-426: The Iapetus Ocean and formed Laurussia , also known as Euramerica. Another historical term for this continent is the Old Red Continent or Old Red Sandstone Continent , in reference to abundant red beds of the Old Red Sandstone during the Devonian. The continent covered 37,000,000 km (14,000,000 sq mi) including several large Arctic continental blocks. With the Caledonian orogeny completed Laurussia

4324-467: The Indian–Australian margin of Gondwana. Other blocks that now form part of southwestern Europe and North America from New England to Florida were still attached to the African-South American margin of Gondwana. This northward drift of terranes across the Tethys also included the Hunic terranes , now spread from Europe to China. Pannotia broke apart in the late Precambrian into Laurentia, Baltica, Siberia, and Gondwana. A series of continental blocks –

4416-468: The Labrador Sea and relocated to the Mid-Atlantic Ridge. The opening of the North Atlantic Ocean had effectively broken Laurasia in two. [REDACTED] Africa [REDACTED] Antarctica [REDACTED] Asia [REDACTED] Australia [REDACTED] Europe [REDACTED] North America [REDACTED] South America [REDACTED] Afro-Eurasia [REDACTED] Americas Avalonia Avalonia

4508-435: The Late Permian (225–251 Myr), the shearing direction of Baltica and Siberia reversed as the Gornostaev shear zone moved to the south and east of Siberia . With this final act during the Late Permian , Sengor's hypothesis on the Central Asian Orogenic Belt evolution was completed. It was estimated that around 2.5 million square kilometers of juvenile materials were added to Asia in around 350 million years, making

4600-464: The Late Devonian and terminated in full collision or the Hercynian/Variscan orogeny in the early Carboniferous (340 Mya). The Variscan orogeny closed the Rheic Ocean (between Avalonia and Armorica) and the Proto-Tethys Ocean (between Armorica and Gondwana) to form the supercontinent Pangaea. The Variscan orogeny is complex and the exact timing and the order of the collisions between involved microcontinents has been debated for decades. Pangaea

4692-404: The Late Triassic-Late Jurassic. During the Carboniferous and Permian, Baltica first collided with Kazakhstania and Siberia, then North China with Mongolia and Siberia. 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

SECTION 50

#1732765946681

4784-531: The Palaeozoic core of North America and continental fragments that now make up part of Europe, collided with Baltica and Avalonia in the Caledonian orogeny c. 430–420 Mya to form Laurussia. In the Late Carboniferous Laurussia and Gondwana formed Pangaea. Siberia and Kazakhstania finally collided with Baltica in the Late Permian to form Laurasia. A series of continental blocks that now form East and Southeast Asia were later added to Laurasia. In 1904–1909 Austrian geologist Eduard Suess proposed that

4876-432: The South Pole located in eastern Baltica, and glacial deposits from this period have been found in Laurentia and Baltica but not in Siberia. A mantle plume (the Central Iapetus Magmatic Province ) forced Laurentia and Baltica to separate ca. 650–600 Mya and the Iapetus Ocean opened between them. Laurentia then began to move quickly (20 cm/year (7.9 in/year)) north towards the Equator where it got stuck over

4968-629: The Tethys Ocean. "Laurussia" was defined by Swiss geologist Peter Ziegler in 1988 as the merger between Laurentia and Baltica along the northern Caledonian suture. The "Old Red Continent" is an informal name often used for the Silurian-Carboniferous deposits in the central landmass of Laurussia. Several earlier supercontinents proposed and debated in the 1990s and later (e.g. Rodinia, Nuna, Nena) included earlier connections between Laurentia, Baltica, and Siberia. These original connections apparently survived through one and possibly even two Wilson Cycles , though their intermittent duration and recurrent fit

5060-427: The Tuva-Mongolia Orocline, intrusions of granites occurred after the mountain building events and were covered by the volcanic and sedimentary rocks which formed during Jurassic to Cretaceous . Ophiolites , which are uplifted and exposed fragments of oceanic crusts with pieces of upper mantle , are considered to be able to provide important information regarding the history of formation and evolution of

5152-491: The amount of accretionary materials at the Kipchak arc decreased towards the southwest as it was more away from the source in Siberia . During the Early Devonian (390-386 Myr), there was no more addition growth of subduction-accretion complexes at the southern end of the Kipchak arc due to the abrupt influx of thick layer of Early Devonian clastic materials and the simultaneous decrease in subduction-related magmatism . This could be explained by collision of Mugodzhar arc at

5244-474: The basement of Nurol basin. See Figure 5G. The Central Asian Orogenic Belt has been on the forefront of research since the 21st century. Despite international efforts of scientists, there are still many questions regarding the Central Asian Orogenic Belt that remain unanswered. They include: The Central Asian Orogenic Belt is rich in natural resources and more extensive study of the region would yield more benefits to society. The Central Asian Orogenic Belt

5336-448: The climate had become arid and these rainforests collapsed , lycopsids (giant mosses) were replaced by treeferns . In the dry climate a detritivorous fauna – including ringed worms , molluscs , and some arthropods  – evolved and diversified, alongside other arthropods who were herbivorous and carnivorous, and tetrapods – insectivores and piscivores such as amphibians and early amniotes . During

5428-410: The continents in the Southern Hemisphere were once merged into a larger continent called Gondwana. In 1915 German meteorologist Alfred Wegener proposed the existence of a supercontinent called Pangaea. In 1937 South African geologist Alexander du Toit proposed that Pangaea was divided into two larger landmasses, Laurasia in the Northern Hemisphere and Gondwana in the Southern Hemisphere, separated by

5520-460: The core of the supercontinent Rodinia , but the exact fit of various continents within Rodinia is debated. In some reconstructions, Baltica was attached to Greenland along its Scandinavian or Caledonide margin while Amazonia was docked along Baltica's Tornquist margin . Australia and East Antarctica were located on Laurentia's western margin. Siberia was located near but at some distance from Laurentia's northern margin in most reconstructions. In

5612-417: The crust. This tectonic activity also resulted in the Permian–Triassic extinction event . Tentional stresses across Eurasia developed into a large system of rift basins (Urengoy, East Uralian-Turgay and Khudosey) and flood basalts in the West Siberian Basin , the Pechora Basin , and South China. Laurasia and Gondwana were equal in size but had distinct geological histories. Gondwana was assembled before

SECTION 60

#1732765946681

5704-481: 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. When the eastern Palaeo-Tethys closed 250–230 Mya, a series of Asian blocks – Sibumasu, Indochina, South China, Qiantang, and Lhasa – formed

5796-403: The end of the Cretaceous, pines were established across Laurasia, from North America to East Asia. From the Triassic to the Early Jurassic, before the break-up of Pangaea, archosaurs (crurotarsans, pterosaurs and dinosaurs including birds) had a global distribution, especially crurotarsans, the group ancestral to the crocodilians . This cosmopolitanism ended as Gondwana fragmented and Laurasia

5888-407: The end of the Devonian similar species were found on both sides of what remained of the Variscan barrier. The oldest tree fossils are from the Middle Devonian pteridophyte Gilboa forest in central Laurussia (today New York, United States). In the late Carboniferous, Laurussia was centred on the Equator and covered by tropical rainforests, commonly referred to as the coal forest . By the Permian,

5980-453: The exposed area of the belt is made of granitoids, while most of the exposed bedrock was formed between 550 Ma and 100 Ma. The Central Asian Orogenic Belt has complex accretionary tectonics , which is well documented in two main areas. One of them, namely "Kazakhstan Orocline", is located in the western portion of the belt, which is in North Xinjiang in China and Kokchetav-Balkash in Kazakhstan . Another one, namely "Tuva-Mongol Orocline",

6072-467: The forefront of the research of accretionary orogens, there is no consensus on the formation history of the Central Asian Orogenic Belt. Further explanation of the two hypotheses for the geological evolution of the Central Asian Orogenic Belt is provided below. The first hypothesis states that the southern margin of the Siberian continent was formed from the accretion of multiple oceanic arcs and possibly parts of continents derived from Gondwana ,

6164-440: The formation of Pangaea, but the assembly of Laurasia occurred during and after the formation of the supercontinent. These differences resulted in different patterns of basin formation and transport of sediments. East Antarctica was the highest ground within Pangaea and produced sediments that were transported across eastern Gondwana but never reached Laurasia. During the Palaeozoic, c. 30–40% of Laurasia but only 10–20% of Gondwana

6256-447: The fractures of chromite. For gold , a large gold mine was found in the Nenjian-Heihe melange zone within the CAOB. This gold mine, namely the Yongxin gold deposit, is a fracture-controlled gold deposit with a thickness of 52m at the largest ore body. Pyrite , which is the most important mineral that host gold, could be found in the mine. The CAOB is also rich in world-class copper . The Laoshankou Iron Oxide-Cu-Au deposit, which

6348-418: The hypotheses posits that oceanic arcs and possible continental blocks derived from Gondwana were added to the Siberian, Russian, and North China cratons via accretion . Another hypothesis suggests that the Central Asian collage is made of accumulated Paleozoic materials that were derived from subduction , accretion , and deformation of a single magmatic arc. Even though the Orogenic Belt has been at

6440-451: The late Phanerozoic time, from around 750 to 150 Ma. Like many other accretionary orogenic belts, the Central Asian Orogenic Belt consists of a huge amount of magmatic arcs , arc-related basins , accretionary complexes , seamounts , continental fragments and ophiolites . It is also considered a relatively distinctive collisional orogenic belt because widespread subduction-accretion complexes and arc magmatic rocks can be found in

6532-452: The late Silurian and lower Devonian , the combined Baltica and Avalonia collided progressively with Laurentia , beginning with the long extremity of Avalonia, which is now attached to North America. The result of this was the formation of Euramerica . At the completion of this stage, the site of Britain was at 30°S and Nova Scotia at about 45°S. This collision is represented by the Caledonian folding or in North America as an early phase in

6624-409: The major terrane of the Kazakhstan orocline was mainly Mesoproterozoic metamorphic rocks , which potentially had Gondwana affinity. They were then covered by the sediments from Neoproterozoic and Cambrian to Lower Ordovician . Island arc volcanic rocks , and chert formed in deep sea environments were the dominant rock types in Paleozoic . By the end of the Ordovician and Silurian ,

6716-508: The north and volcanic rocks which formed in the Paleozoic in the south of the orocline . For the northern portion of the orocline , it contains Precambrian to early Paleozoic metamorphic rocks , Neoproterozoic ophiolites , volcanic rocks formed in the early Paleozoic island arcs , and some associated volcaniclastic sediments. These rocks were then covered by the Devonian to Carboniferous sediments and were influenced by

6808-464: The north of Baltica with the southern end of the Kipchak arc. On the other hand, a subduction-accretion wedge started to grow at the north of the Kipchak arc. By Late Devonian (367-362 Myr), subduction-accretion and arc magmatism produced a continental crust that had a normal thickness. During Early Carboniferous (332-318 Myr), the Baltica craton migrated towards Siberia craton , which led to

6900-497: The north of the Siberia craton. Accretionary complexes was formed due to subduction of microcontinents at the north of the Siberia craton . The accretionary materials at the Kipchak arc decreased towards the southwest as it is more away from the source in Siberia . See Figure 5B. Subduction-accretion wedge grew at the north of the Kipchak arc. See Figure 5C. See Figure 5E. See Figure 5F. Alkaline magmatism at

6992-486: The north of the Siberia craton. During the Middle Silurian (430-424 Myr), the Kipchak arc, which is the fragment formed due to the rifting of Baltica and Siberia , had its northern end attached to the Siberia craton and its southern end free from attachment to the Baltica craton . Meanwhile, the accretionary complex formed during the subduction of microcontinents at the north of the Siberia craton and

7084-464: The northern shores of Gondwana (north of Australia in modern coordinates) and the closure of the same ocean reassembled them along the same shores 500–460 Mya resulting in Gondwana at its largest extent. The break-up of Rodinia also resulted in the opening of the long-lived Paleo-Asian Ocean between Baltica and Siberia in the north and Tarim and North China in the south. The closure of this ocean

7176-578: The open ocean and therefore the oceanic gaps between continents are easily detected in the fossil records of marine bottom dwellers and non-marine species. By the Late Ordovician, when continents were pushed closer together closing the oceanic gaps, benthos (brachiopods and trilobites) could spread between continents while ostracods and fishes remained isolated. As Laurussia formed during the Devonian and Pangaea formed, fish species in both Laurussia and Gondwana began to migrate between continents and before

7268-494: The other staying in Laurasia (until further descendants switched to Gondwana starting from the Jurassic ). In the early Eocene a peak in global warming led to a pan-Arctic fauna with alligators and amphibians present north of the Arctic Circle. In the early Palaeogene, landbridges still connected continents, allowing land animals to migrate between them. On the other hand, submerged areas occasionally divided continents:

7360-605: The reconstruction of some Russian geologists, however, the southern margin (modern coordinates) of Siberia merged with the northern margin of Laurentia, and these two continents broke up along what is now the 3,000 km (1,900 mi)-long Central Asian Foldbelt no later than 570 Mya and traces of this breakup can still be found in the Franklin dike swarm in northern Canada and the Aldan Shield in Siberia. The Proto-Pacific opened and Rodinia began to breakup during

7452-402: The region, but collision-related foreland basins are not common. The formation history of the Central Asian Orogenic Belt is complex and highly disputed among academic scientists. Currently, there are two major evolutionary hypotheses that could potentially explain the geological history of the Central Asian Orogenic Belt. One of the hypothesis stated by geologist Celal Sengor proposed that

7544-556: The rifting of western Pangaea had already begun. Pangaea split in two as the Tethys Seaway opened between Gondwana and Laurasia in the Late Jurassic. The fossil record, however, suggests the intermittent presence of a Trans-Tethys land bridge, though the location and duration of such a land bridge remains enigmatic. Pine trees evolved in the early Mesozoic c. 250 Mya and the pine genus originated in Laurasia in

7636-830: The shores of Rodinia together with island arcs now found in the Arabian-Nubian Shield (900–700 Ma) and Tocantins in central Brazil (950–900 Ma) and the basement of Avalonia is most likely of the same age. During the Precambrian-Cambrian transition, Avalonia was located in a cool-water environment and even underwent a glaciation. The Moroccan Anti-Atlas range in West Gondwana was, in contrast, characterised by evaporites , evidence of desiccation , and had thrombolites . Avalonia and Gondwana must therefore have been located far from each other during this period. The two did, however, share

7728-836: The volcanic activities during the Permian . For the southern portion of the Tuva-Mongolia Orocline, the majority of rocks there are early to late Paleozoic volcanic rocks with ophiolites formed during ocean closures, most notably the closure of the Palaeo-Asian Ocean that began in the Early Carboniferous and ended in the Late Permian or Early Triassic . The volcaniclastic sediments formed during Late Carboniferous to Permian were also common in this region. For both portions in

7820-457: The western margin of Laurentia and northern margin of Baltica (modern coordinates), and was completed c. 1,300—1,200 Mya, a period during which mafic dike swarms were emplaced, including MacKenzie and Sudbury in Laurentia. Traces left by large igneous provinces provide evidences for continental mergers during this period. Those related to Proto-Laurasia includes: In the vast majority of plate tectonic reconstructions, Laurentia formed

7912-402: The world. It is important to note that some of the richest hydrocarbon reserves in the world can be found in the region near Central Asian Orogenic Belt. Within the Orogenic Belt, oil- and gas-bearing basins were developed, such as Junggar , Santanghu , and Songliao basins, of which the former two are located at the south-western portion of the Orogenic Belt and the later one is located at

8004-469: Was a microcontinent in the Paleozoic era . Crustal fragments of this former microcontinent underlie south-west Great Britain , southern Ireland , and the eastern coast of North America . It is the source of many of the older rocks of Western Europe , Atlantic Canada , and parts of the coastal United States . Avalonia is named for the Avalon Peninsula in Newfoundland . Avalonia developed as

8096-543: Was assembled. Pterosaur diversity reach a maximum in the Late Jurassic—Early Cretaceous and plate tectonic didn't affect the distribution of these flying reptiles. Crocodilian ancestors also diversified during the Early Cretaceous but were divided into Laurasian and Gondwanan populations; true crocodilians evolved from the former. The distribution of the three major groups of dinosaurs  –

8188-715: Was completely assembled by the Permian except for the Asian blocks. The supercontinent was centred on the Equator during the Triassic and Jurassic, a period that saw the emergence of the Pangaean megamonsoon . Heavy rainfall resulted in high groundwater tables, in turn resulting in peat formation and extensive coal deposits. During the Cambrian and Early Ordovician, when wide oceans separated all major continents, only pelagic marine organisms, such as plankton, could move freely across

8280-581: Was covered by shallow marine water. During the assembly of Pangaea Laurasia grew as continental blocks broke off Gondwana's northern margin; pulled by old closing oceans in front of them and pushed by new opening oceans behind them. During the Neoproterozoic-Early Paleozoic break-up of Rodinia the opening of the Proto-Tethys Ocean split the Asian blocks – Tarim, Qaidam, Alex, North China, and South China – from

8372-461: Was delimited thus: During the Devonian (416-359 Mya) the combined landmass of Baltica and Avalonia rotated around Laurentia, which remained static near the Equator. The Laurentian warm, shallow seas and on shelves a diverse assemblage of benthos evolved, including the largest trilobites exceeding 1 m (3 ft 3 in). The Old Red Sandstone Continent stretched across northern Laurentia and into Avalonia and Baltica but for most of

8464-1029: Was later rotated away again as the African part of Gondwana strike-slipped past it. This last movement caused the Alpine orogeny including the raising of the Pyrenees during the Miocene and Pliocene . As a result of this, part of Avalonia is now to be found on each side of the Straits of Gibraltar . [REDACTED] Africa [REDACTED] Antarctica [REDACTED] Asia [REDACTED] Australia [REDACTED] Europe [REDACTED] North America [REDACTED] South America [REDACTED] Afro-Eurasia [REDACTED] Americas [REDACTED] Eurasia [REDACTED] Oceania Central Asian Foldbelt The Central Asian Orogenic Belt ( CAOB ), also called

#680319