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The Acadian orogeny is a long-lasting mountain building event which began in the Middle Devonian, reaching a climax in the early Late Devonian. It was active for approximately 50 million years, beginning roughly around 375 million years ago, with deformational, plutonic, and metamorphic events extending into the Early Mississippian. The Acadian orogeny is the third of the four orogenies that formed the Appalachian orogen and subsequent basin. The preceding orogenies consisted of the Potomac and Taconic orogeny, which followed a rift/drift stage in the Late Neoproterozoic. The Acadian orogeny involved the collision of a series of Avalonian continental fragments with the Laurasian continent. Geographically, the Acadian orogeny extended from the Canadian Maritime provinces migrating in a southwesterly direction toward Alabama. However, the Northern Appalachian region, from New England northeastward into Gaspé region of Canada, was the most greatly affected region by the collision.
The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the East coast of the United States. As the mountain chain eroded in the Silurian and Devonian periods, sediments from the mountain chain spread throughout the present-day Appalachians and midcontinental North America.
The Windermere Supergroup is a geological unit formed during the Ordovician to Silurian periods ~450 million years ago, and exposed in northwest England, including the Pennines and correlates along its strike, in the Isle of Man and Ireland, and down-dip in the Southern Uplands and Welsh Borderlands. It underlies much of north England's younger cover, extending south to East Anglia. It formed as a foreland basin, in a similar setting to the modern Ganges basin, fronting the continent of Avalonia as the remains of the attached Iapetus ocean subducted under Laurentia.
The geology of Wales is complex and varied; its study has been of considerable historical significance in the development of geology as a science. All geological periods from the Cryogenian to the Jurassic are represented at outcrop, whilst younger sedimentary rocks occur beneath the seas immediately off the Welsh coast. The effects of two mountain-building episodes have left their mark in the faulting and folding of much of the Palaeozoic rock sequence. Superficial deposits and landforms created during the present Quaternary period by water and ice are also plentiful and contribute to a remarkably diverse landscape of mountains, hills and coastal plains.
The Orcadian Basin is a sedimentary basin of Devonian age that formed mainly as a result of extensional tectonics in northeastern Scotland after the end of the Caledonian orogeny. During part of its history, the basin was filled by a lake now known as Lake Orcadie. In that lacustrine environment, a sequence of finely bedded sedimentary rocks was deposited, containing well-preserved fish fossils, with alternating layers of mudstone and coarse siltstone to very fine sandstone. These flagstones split easily along the bedding and have been used as building material for thousands of years. The deposits of the Orcadian Basin form part of the Old Red Sandstone (ORS). The lithostratigraphic terms lower, middle and upper ORS, however, do not necessarily match exactly with sediments of lower, middle and upper Devonian age, as the base of the ORS is now known to be in the Silurian and the top in the Carboniferous.
The Saxothuringian Zone, Saxo-Thuringian zone or Saxothuringicum is in geology a structural or tectonic zone in the Hercynian or Variscan orogen of central and western Europe. Because rocks of Hercynian age are in most places covered by younger strata, the zone is not everywhere visible at the surface. Places where it crops out are the northern Bohemian Massif, the Spessart, the Odenwald, the northern parts of the Black Forest and Vosges and the southern part of the Taunus. West of the Vosges terranes on both sides of the English Channel are also seen as part of the zone, for example the Lizard complex in Cornwall or the Léon Zone of the Armorican Massif (Brittany).
The Moine Supergroup is a sequence of Neoproterozoic metamorphic rocks that form the dominant outcrop of the Scottish Highlands between the Moine Thrust Belt to the northwest and the Great Glen Fault to the southeast. The sequence is metasedimentary in nature and was metamorphosed and deformed in a series of tectonic events during the Late Proterozoic and Early Paleozoic. It takes its name from A' Mhòine, a peat bog in northern Sutherland.
The Massif Central is one of the two large basement massifs in France, the other being the Armorican Massif. The Massif Central's geological evolution started in the late Neoproterozoic and continues to this day. It has been shaped mainly by the Caledonian orogeny and the Variscan orogeny. The Alpine orogeny has also left its imprints, probably causing the important Cenozoic volcanism. The Massif Central has a very long geological history, underlined by zircon ages dating back into the Archaean 3 billion years ago. Structurally it consists mainly of stacked metamorphic basement nappes.
The Génis Unit is a Paleozoic metasedimentary succession of the southern Limousin and belongs geologically to the Variscan basement of the French Massif Central. The unit covers the age range Cambrian/Ordovician till Devonian.
The Hebridean Terrane is one of the terranes that form part of the Caledonian orogenic belt in northwest Scotland. Its boundary with the neighbouring Northern Highland Terrane is formed by the Moine Thrust Belt. The basement is formed by Archaean and Paleoproterozoic gneisses of the Lewisian complex, unconformably overlain by the Neoproterozoic Torridonian sediments, which in turn are unconformably overlain by a sequence of Cambro–Ordovician sediments. It formed part of the Laurentian foreland during the Caledonian continental collision.
The Aber Dinlle Fault is a SW-NE trending fault in North Wales. It forms part of the Menai Strait Fault System, with the Berw and Dinorwic Faults. It lies close to the epicentre of the 1984 Llŷn Peninsula earthquake, although it is not thought to have been responsible for that event. The fault was active during deposition of Ordovician rocks in the Welsh Basin. It was reactivated as a normal fault in the Carboniferous with a downthrow to the northwest and again reactivated as a reverse fault during Late Carboniferous inversion associated with the Variscan Orogeny.
The Ceibwr Bay Fault is a WSW-ENE trending fault zone that cuts Ordovician rocks of the Ashgill Nantmel Mudstones Formation and the Caradoc Dinas Island Formation. The fault is exposed on the south side of Cardigan Bay in Wales and forms part of the Fishguard-Cardigan Fault Zone. It extends from the coast at Ceibwr Bay at its western end to the coast at Aberporth at its eastern end. The fault zone is thought to have been active as a normal fault throughout the deposition of the Ordovician sequence.
The Welsh Basin was a northeast-southwest aligned back-arc depositional basin during the Cambrian, Ordovician and Silurian periods during which a considerable thickness of marine sediments was laid down in the area. To the southeast lay the Midland Platform and to the northwest, within the Iapetus Ocean, through what is now Ireland and the Lake District, was an island arc; a northeast-southwest aligned Irish Sea landmass which was associated with volcanic activity. Examination of the sediments and associated fossils allows the deeper centre of the basin to be distinguished from shallower 'platform' areas along its southeastern margins. From the middle Silurian onwards, collision of Avalonia with the more northerly continent of Laurentia occurred giving rise to the Caledonian Orogeny. The inversion of the basin occurred at that time i.e. its uplift and deformation.
The Wrekin Terrane is one of five inferred fault bounded terranes that make up the basement rocks of the southern United Kingdom. The other notable geological terranes in the region are the Charnwood Terrane, Fenland Terrane, Cymru Terrane and the Monian Composite Terrane. The Wrekin Terrane is bounded to the west by the Welsh Borderland Fault System and to the east by the Malvern Lineament. The geological terrane to the west is the Cymru Terrane and to the east is Charnwood Terrane. The majority of rocks in the area are associated with the outcrops that are evident at the faulted boundaries.
Pre-collisional Himalaya is the arrangement of the Himalayan rock units before mountain-building processes resulted in the collision of Asia and India. The collision began in the Cenozoic and it is a type locality of a continental-continental collision. The reconstruction of the initial configuration of the rock units and the relationship between them is highly controversial, and major concerns relate to the arrangements of the different rock units in three dimensions. Several models have been advanced to explain the possible arrangements and petrogenesis of the rock units.
Hainan Island, located in the South China Sea off the Chinese coast and separated from mainland China by the Qiongzhou Strait, has a complex geological history that it has experienced multiple stages of metamorphism, volcanic and intrusive activities, tectonic drifting and more. The oldest rocks, the Proterozoic metamorphic basement, are not widely exposed, but mostly found in the western part of the Island.
The geology of South Korea includes rocks dating to the Archean and two large massifs of metamorphic rock as the crystalline basement, overlain by thick sedimentary sequences, younger metamorphic rocks and volcanic deposits. Although extent is small, Geology is diverse, and there are diverse rocks that were formed during the Precambrian to Cenozoic Era in the Korea Peninsula.
The geology of Snowdonia National Park in North Wales is dominated by sedimentary and volcanic rocks from the Cambrian and Ordovician periods with intrusions of Ordovician and Silurian age. There are Silurian and Cenozoic sedimentary rocks on the park's margins. The succession was intensely faulted and folded during the Caledonian Orogeny. The region was uplifted as the North Atlantic Ocean opened during the Cenozoic. The current mountainous landscape arises from repeated glaciations during the Quaternary period.
The Hornelen Basin is a sedimentary basin in Vestland, Norway, containing an estimated 25 km stratigraphic thickness of coarse clastic sedimentary rocks of Devonian age. It forms part of a group of basins of similar age along the west coast of Norway between Sognefjord and Nordfjord, related to movement on the Nordfjord-Sogn Detachment. It formed as a result of extensional tectonics as part of the post-orogenic collapse of crust that was thickened during the Caledonian Orogeny towards the end of the Silurian period. It is named for the mountain Hornelen on the northern margin of the basin.
The Parnaíba Basin is a large cratonic sedimentary basin located in the North and Northeast portion of Brazil. About 50% of its areal distribution occurs in the state of Maranhão, and the other 50% occurring in the state of Pará, Piauí, Tocantins, and Ceará. It is one of the largest Paleozoic basins in the South American Platform. The basin has a roughly ellipsoidal shape, occupies over 600,000 km2, and is composed of ~3.4 km of mainly Paleozoic sedimentary rock that overlies localized rifts.
References
- ↑ Woodcock, N.H.; Butler, A,J.; Davies, J.R.; Waters R.A. (1996). "Sequence stratigraphical analysis of late ordovician and early Silurian depositional systems in the Welsh Basin: a critical assessment". In Hesselbo S.E. & Parkinson D.N. (ed.). Sequence Stratigraphy in British Geology. Special Publications. Vol. 103. London: Geological Society. pp. 197–208. ISBN 978-1-897799-49-9 . Retrieved 17 December 2010.
- ↑ Roberts, B.; Merriman R.J.; Hirons S.R.; Fletcher C.J.N.; Wilson D. (1996). "Synchronous very low-grade metamorphism, contraction and inversion in the central part of the Welsh Lower Palaeozoic Basin". Journal of the Geological Society. 153 (2): 277–285. Bibcode:1996JGSoc.153..277R. doi:10.1144/gsjgs.153.2.0277. S2CID 128972267 . Retrieved 17 December 2010.
52°16′N3°40′W / 52.26°N 3.66°W
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