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Laurasia, a portmanteau for Laurentia and Eurasia, was the more northern of two minor supercontinents that formed part of the Pangaea supercontinent from c.425 million years ago (Mya) to 200 Mya. It separated from Gondwana 215 to 175 Mya during the breakup of Pangaea, drifting farther north after the split and finally broke apart with the opening of the North Atlantic Ocean c. 56 Mya.
Columbia, also known as Nuna and Hudsonland, was one of Earth's ancient supercontinents. It was first proposed by Rogers & Santosh 2002 and is thought to have existed approximately 2,500 to 1,500 million years ago in the Paleoproterozoic Era. Zhao et al. 2002 proposed that the assembly of the supercontinent Columbia was completed by global-scale collisional events during 2.1–1.8 Ga.
Arctica or Arctida was an ancient continent which formed approximately 2.565 billion years ago in the Neoarchean era. It was made of Archaean cratons, including the Siberian Craton, with its Anabar/Aldan shields in Siberia, and the Slave, Wyoming, Superior, and North Atlantic cratons in North America. Arctica was named by Rogers 1996 because the Arctic Ocean formed by the separation of the North American and Siberian cratons. Russian geologists writing in English call the continent "Arctida" since it was given that name in 1987, alternatively the Hyperborean craton, in reference to the hyperboreans in Greek mythology.
The Congo Craton, covered by the Palaeozoic-to-recent Congo Basin, is an ancient Precambrian craton that with four others makes up the modern continent of Africa. These cratons were formed between about 3.6 and 2.0 billion years ago and have been tectonically stable since that time. All of these cratons are bounded by younger fold belts formed between 2.0 billion and 300 million years ago.
A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive and extrusive, arising when magma travels through the crust towards the surface. The formation of LIPs is variously attributed to mantle plumes or to processes associated with divergent plate tectonics. The formation of some of the LIPs the past 500 million years coincide in time with mass extinctions and rapid climatic changes, which has led to numerous hypotheses about the causal relationships. LIPs are fundamentally different from any other currently active volcanoes or volcanic systems.
The Moine Thrust Belt or Moine Thrust Zone is a linear tectonic feature in the Scottish Highlands which runs from Loch Eriboll on the north coast 190 kilometres (120 mi) south-west to the Sleat peninsula on the Isle of Skye. The thrust belt consists of a series of thrust faults that branch off the Moine Thrust itself. Topographically, the belt marks a change from rugged, terraced mountains with steep sides sculptured from weathered igneous, sedimentary and metamorphic rocks in the west to an extensive landscape of rolling hills over a metamorphic rock base to the east. Mountains within the belt display complexly folded and faulted layers and the width of the main part of the zone varies up to 10 kilometres (6.2 mi), although it is significantly wider on Skye.
The Pan-African orogeny was a series of major Neoproterozoic orogenic events which related to the formation of the supercontinents Gondwana and Pannotia about 600 million years ago. This orogeny is also known as the Pan-Gondwanan or Saldanian Orogeny. The Pan-African orogeny and the Grenville orogeny are the largest known systems of orogenies on Earth. The sum of the continental crust formed in the Pan-African orogeny and the Grenville orogeny makes the Neoproterozoic the period of Earth's history that has produced most continental crust.
The Kaapvaal Craton, along with the Pilbara Craton of Western Australia, are the only remaining areas of pristine 3.6–2.5 Ga crust on Earth. Similarities of rock records from both these cratons, especially of the overlying late Archean sequences, suggest that they were once part of the Vaalbara supercontinent.
The geology of Antarctica covers the geological development of the continent through the Archean, Proterozoic and Phanerozoic eons.
Volcanology of Canada includes lava flows, lava plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes, and maars, along with examples of more less common volcanic forms such as tuyas and subglacial mounds. It has a very complex volcanological history spanning from the Precambrian eon at least 3.11 billion years ago when this part of the North American continent began to form.
A dike swarm or dyke swarm is a large geological structure consisting of a major group of parallel, linear, or radially oriented dikes intruded within continental crust. They consist of several to hundreds of dikes emplaced more or less contemporaneously during a single intrusive event, and are magmatic and stratigraphic. Such dike swarms may form a large igneous province and are the roots of a volcanic province.
The Kangaamiut dike swarm is a 2.04 billion year old dike swarm located in the Qeqqata region of western Greenland. The dikes cut Archean orthogneisses and are exposed along approximately 150 km (93 mi) of the coast and a similar distance up to the inland ice to the east, covering an area of about 18,000 km2 (6,900 sq mi). To the north it is bounded by the paleoproterozoic Ikertooq shear zone while to the south the boundary is gradational with a gradual reduction in the density of dikes. The dike swarm was intruded during a phase of extensional tectonics. They were later deformed during the Nagssugtoqidian orogeny, with the amount of strain increasing towards the Iqertooq shear zone.
Greenland is the largest island on Earth. Only one-fifth of its surface area is exposed bedrock, the rest being covered by ice. The exposed surface is approximately 410,000 km2.
The North Atlantic Igneous Province (NAIP) is a large igneous province in the North Atlantic, centered on Iceland. In the Paleogene, the province formed the Thulean Plateau, a large basaltic lava plain, which extended over at least 1.3 million km2 (500 thousand sq mi) in area and 6.6 million km3 (1.6 million cu mi) in volume. The plateau was broken up during the opening of the North Atlantic Ocean leaving remnants existing in Northern Ireland, bits of northwestern Scotland, the Faroe Islands, bits of northwestern Iceland, eastern Greenland and western Norway and many of the islands located in the north eastern portion of the North Atlantic Ocean. The igneous province is the origin of the Giant's Causeway and Fingal's Cave. The province is also known as Brito-Arctic province and the portions of the province in the British Isles is also called the British Tertiary Volcanic Province or British Tertiary Igneous Province.
Volcanology of Northern Canada includes hundreds of volcanic areas and extensive lava formations across Northern Canada. The region's different volcano and lava types originate from different tectonic settings and types of volcanic eruptions, ranging from passive lava eruptions to violent explosive eruptions. Northern Canada has a record of very large volumes of magmatic rock called large igneous provinces. They are represented by deep-level plumbing systems consisting of giant dike swarms, sill provinces and layered intrusions.
The Greenland Plate is a supposed tectonic plate bounded to the west by Nares Strait, a probable transform fault, on the southwest by the Ungava transform underlying Davis Strait, on the southeast by the Mid-Atlantic Ridge, and the northeast by the Gakkel Ridge, with its northwest border is still being explored. The Greenland craton is made up of some of the oldest rocks on Earth. The Isua greenstone belt in southwestern Greenland contains the oldest known rocks on Earth dated at 3.7–3.8 billion years old.
The geology of Russia, the world's largest country, which extends over much of northern Eurasia, consists of several stable cratons and sedimentary platforms bounded by orogenic (mountain) belts.
The Maniitsoq structure is a 100 km (62 mi) wide circular region with unusual geological features believed to be the results of a massive asteroid or comet impact about three billion years ago. The region is centered about 55 km (34 mi) south-east of the town of Maniitsoq, Greenland, at coordinates 65°15′N51°50′W.
The Canadian Arctic Rift System is a major North American geological structure extending from the Labrador Sea in the southeast through Davis Strait, Baffin Bay and the Arctic Archipelago in the northwest. It consists of a series of interconnected rifts that formed during the Paleozoic, Mesozoic and Cenozoic eras. Extensional stresses along the entire length of the rift system have resulted in a variety of tectonic features, including grabens, half-grabens, basins and faults.
The Laxfordian orogeny was an orogeny mountain building event between 1.9 and 1 billion years ago. It primarily affected the North Atlantic Craton, in particular a section that cleaved off during the Mesozoic as the Scottish Shield Fragment.
References
- ↑ Mayborn, K.R.; Lesher, C.E. (2006). "Origin and evolution of the Kangâmiut mafic dyke swarm, West Greenland" (PDF). In Garde, A.A.; Kalsbeek, F. (eds.). Precambrian crustal evolution and Cretaceous-Palaeogene faulting in West Greenland. Geological Survey of Denmark and Greenland Bulletin. 11. pp. 61–86.
- ↑ Garde, A.A.; Hollis, J.A. (2010). "A buried Palaeoproterozoic spreading ridge in the northern Nagssugtoqidian orogen, West Greenland". In Kusky, T. M; Zhai, M.-G.; Xiao, W. (eds.). The Evolving Continents: Understanding Processes of Continental Growth. Special Publications. 338. Geological Society, London. p. 213–234. CiteSeerX 10.1.1.980.1494 . doi:10.1144/SP338.11. ISBN 9781862393035.