Atlantica ( Greek : Ατλαντικα ; Atlantika ) is an ancient continent that formed during the Proterozoic about 2,000 million years ago (two billion years ago, Ga ) from various 2 Ga cratons located in what are now West Africa and eastern South America . The name, introduced by John Rogers in 1996, was chosen because the parts of the ancient continent are now located on opposite sides of the South Atlantic Ocean .
25-507: Atlantica formed simultaneously with Nena at about 1.9 Ga from Archaean cratons, including Amazonia in present-day South America, and the Congo, West Africa and North Africa Cratons in Africa. Atlantica separated from Nena between 1.6–1.4 Ga when Columbia — a supercontinent composed of Ur , Nena, and Atlantica — fragmented. Atlantica and continents Nena and Ur and some minor plates formed
50-481: A suevite and sedimentary package composed of the Onaping (fallback breccias ), Onwatin, and Chelmsford Formations in stratigraphic succession. Footwall rocks, associated with the impact event, consist of Sudbury Breccia ( pseudotachylite ), footwall breccia, radial and concentric quartz dioritic breccia dikes (polymict impact melt breccias), and the discontinuous sub layer. Because considerable erosion has occurred since
75-533: A baseline westward from Lake Nipissing , provincial land surveyor Albert Salter located magnetic abnormalities in the area that were strongly suggestive of mineral deposits, especially near what later became the Creighton Mine . The area was examined by Alexander Murray of the Geological Survey of Canada , who confirmed "the presence of an immense mass of magnetic trap". Due to the then-remoteness of
100-483: A meteorite was the cause of the Sudbury geological structures. A further difficulty in proving that the Sudbury complex was formed by meteorite impact rather than by ordinary igneous processes was that the region was volcanically active at around the same time as the impact, and some weathered volcanic structures can look like meteorite collision structures. Since its discovery, a layer of breccia has been found associated with
125-579: Is a stub . You can help Misplaced Pages by expanding it . Sudbury Basin The Sudbury Basin ( / ˈ s ʌ d b ə r i / ), also known as Sudbury Structure or the Sudbury Nickel Irruptive , is a major geological structure in Ontario , Canada. It is the third-largest known impact structure on Earth , as well as one of the oldest. The structure, the eroded remnant of an impact crater,
150-581: Is the third-largest crater on Earth, after the 300 km (190 mi) Vredefort impact structure in South Africa , and the 180 km (110 mi) Chicxulub crater under Yucatán , Mexico . Geochemical evidence suggests that the impactor was likely a chondrite asteroid or a comet with a chondritic component. The full extent of the Sudbury Basin is 62 km (39 mi) long, 30 km (19 mi) wide and 15 km (9.3 mi) deep although
175-636: The Grenville Front Tectonic Zone and the eastern end of the Great Lakes Tectonic Zone , but the structures are not directly related to one another in the sense of resulting from the same geological processes. The large impact crater filled with magma containing nickel , copper , palladium , gold , the platinum group and other metals . This magma formed into pyrrhotite , chalcopyrite and pentlandite rocks, as well as cubanite and magnetite . In 1856 while surveying
200-620: The Penokean , Makkovikan , Ketilidian , and Svecofennian orogenies . However, because Nena excludes several known Archaean cratons, including those in India and Australia, it is strictly speaking not a supercontinent. Although Nena and Nuna share many similarities, Nena accounted for a larger landmass than Nuna. This extended landmass included the Angara, Antarctica, Baltica , Laurentia , and Siberia bodies. Nena, or Nuna, can, nevertheless be thought of as
225-550: The supercontinent Rodinia about 1 Ga ago. Between 1–0.5 Ga Rodinia split into three new continents: Laurasia and East and West Gondwana ; Atlantica became the nucleus of West Gondwana. During this later stage, the Neoproterozoic era, a Brasiliano - Pan African orogenic system developed. The central part of this system, the Araçuaí -West Congo orogen , has left a distinct pattern of deformations, still present on both sides of
250-486: The Angara, Antarctica, and Siberia landmasses. Throughout the amalgamation of the microcontinents which would form proto-Nena, several significant geologic processes occurred including orogenesis and continental magmatic accretion. The by-products of these processes can be found numerous regions such as southwest Ontario, northwest British Isles, and Greenland. These by-products include the Marquette Range supergroup and
275-527: The Atlantic Ocean. [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 Nena (supercontinent) Nena , an acronym for Northern Europe – North America ,
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#1732852318096300-498: The Holloway recommendations were in line with the advocacy of Aeneas McCharles , a 19th-century prospector and early mine owner. As a result of these metal deposits, the Sudbury area is one of the world's major mining communities, and has fathered Vale Inco and Falconbridge Xstrata . The Basin is one of the world's largest suppliers of nickel and copper ores. Most of these mineral deposits are found on its outer rim. Most soils in
325-845: The Moran Lake and lower Aillik groups northwest of the Makkovik orogen. These geologic findings provided a basis for the concept of the Nena supercontinent. Nena as a continent has been associated with the Sudbury Basin Impact . [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 This palaeogeography article
350-638: The Sudbury Basin are acidic and sandy; where well drained they usually belong to the Podzol great soil group. Poor drainage results in gleysols and peats . Regardless of drainage or classification, the Basin has deeper soils than the surrounding terrain, much of which is mapped as Rockland (a combination of frequent bedrock outcrops and shallow soil). Consequently, considerable areas in the Basin have been cleared for agriculture. The best soils, mapped as Azilda series and Bradley series, occur around Chelmsford . NASA used
375-584: The Sudbury area, Salter's discovery did not have much immediate effect. The construction of the Canadian Pacific Railway through the area, however, made mineral exploration more feasible. The development of a mining settlement occurred in 1883 after blasting at the railway construction site revealed a large concentration of nickel and copper ore at what is now the Murray Mine site, named by owners William and Thomas Murray. The Vermillion Mine , which
400-463: The Sudbury event, an estimated 6 km (3.7 mi) in the North Range, it is difficult to directly constrain the actual size of the diameter of the original transient cavity, or the final rim diameter. The deformation of the Sudbury structure occurred in five main deformation events (by age in millions of years): Some 1.8 billion years of weathering and deformation made it difficult to prove that
425-650: The basin. An Ontario Historical Plaque was erected by the province to commemorate the discovery of the Sudbury Basin. The Sudbury basin formed as a result of an impact into the Nuna supercontinent from a large impactor body approximately 10–15 km (6.2–9.3 mi) in diameter that occurred 1.849 billion years ago in the Paleoproterozoic era. Debris from the impact was scattered over an area of 1,600,000 km (620,000 sq mi) thrown more than 800 km (500 mi); and ejecta —rock fragments ejected by
450-601: The concentration and distribution of siderophile elements as well as the size of the area where the impact melted the rock indicated that a comet rather than an asteroid most likely caused the crater. The Sudbury Basin is located near a number of other geological structures, including the Temagami Magnetic Anomaly , the Lake Wanapitei impact crater, the western end of the Ottawa-Bonnechere Graben ,
475-463: The core of Columbia , another supercontinent concept with several proposed configurations. The first concept of the Nena supercontinent originated with the southern regions of proto-Laurentia and the western regions proto-Baltica merging throughout the Proterozoic eon. This concept would eventually be developed to the modern day conceptualization of the Nena supercontinent which includes additions of
500-401: The impact event and stressed rock formations have been fully mapped. Reports published in the late 1960s described geological features that were said to be distinctive of meteorite impact, including shatter cones and shock-deformed quartz crystals in the underlying rock. Geologists reached consensus by about 1970 that the Sudbury basin was formed by a meteorite impact. In 2014, analysis of
525-417: The impact—have been found as far away as Minnesota . Models suggest that for such a large impact, debris was most likely scattered globally, but has since been eroded. Its present size is believed to be a smaller portion of a 130 km (81 mi) round crater that the meteor originally created. Subsequent geological processes have deformed the crater into the current smaller oval shape. Sudbury Basin
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#1732852318096550-710: The modern ground surface is much shallower. The main units characterizing the Sudbury Structure can be subdivided into three groups: the Sudbury Igneous Complex (SIC), the Whitewater Group, and footwall brecciated country rocks that include offset dikes and the Sub layer. The SIC is believed to be a stratified impact melt sheet composed from the base up of sub layer norite, mafic norite, felsic norite, quartz gabbro, and granophyre. The Whitewater Group consists of
575-476: Was formed by the impact of an asteroid 1.849 billion years ago in the Paleoproterozoic era. The basin is located on the Canadian Shield in the city of Greater Sudbury , Ontario . The former municipalities of Rayside-Balfour , Valley East and Capreol lie within the Sudbury Basin, which is referred to locally as "The Valley". The urban core of the former city of Sudbury lies on the southern outskirts of
600-468: Was the Early Proterozoic amalgamation of Baltica and Laurentia into a single "cratonic landmass", a name first proposed in 1990. Since then several similar Proterozoic supercontinents have been proposed, including Nuna and Arctica , that include other Archaean cratons , such as Siberia and East Antarctica . In the original concept Nena formed c. 1,900 million years ago in
625-484: Was the first in the Basin to be exploited, was the site at which Frank Sperry (a chemist of the Canadian Copper Company) made the first identification in 1889 of the arsenide of platinum which bears his name . As a result of the 1917 Royal Ontario Nickel Commission , which was chaired by Englishman George Thomas Holloway , the legislative structure of the prospecting trade was significantly altered. Some of
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