Sudbury Basin
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The Sudbury Basin (), also known as Sudbury Structure or the Sudbury Nickel Irruptive, is a major
geological Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Eart ...
structure in
Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
, Canada. It is the third-largest known
impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters ...
or
astrobleme An impact structure is a generally circular or craterlike geologic structure of deformed bedrock or sediment produced by impact on a planetary surface, whatever the stage of erosion of the structure. In contrast, an impact crater is the sur ...
on
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
, as well as one of the oldest. The crater formed 1.849 billion years ago in the
Paleoproterozoic The Paleoproterozoic Era (;, also spelled Palaeoproterozoic), spanning the time period from (2.5–1.6  Ga), is the first of the three sub-divisions (eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest era of the Earth's ...
era. The basin is located on the
Canadian Shield The Canadian Shield (french: Bouclier canadien ), also called the Laurentian Plateau, is a geologic shield, a large area of exposed Precambrian igneous and high-grade metamorphic rocks. It forms the North American Craton (or Laurentia), the anc ...
in the city of
Greater Sudbury Sudbury, officially the City of Greater Sudbury is the largest city in Northern Ontario by population, with a population of 166,004 at the 2021 Canadian Census. By land area, it is the largest in Ontario and the List of the largest cities and to ...
,
Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
. The former municipalities of
Rayside-Balfour Rayside-Balfour (1996 census population 16,050) was a town in Ontario, Canada, which existed from 1973 to 2000. It is now part of the city of Greater Sudbury. The town was created as part of the Regional Municipality of Sudbury and took its name ...
,
Valley East A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams ove ...
and
Capreol Capreol ( ) is a community in the Ontario city of Greater Sudbury. Situated on the Vermilion River (35 mins north of the downtown core), Capreol is the city's northernmost populated area. From 1918 to 2000, Capreol existed as an independent to ...
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 the basin. An Ontario Historical Plaque was erected by the province to commemorate the discovery of the Sudbury Basin.


Formation

The Sudbury basin formed as a result of an
impact Impact may refer to: * Impact (mechanics), a high force or shock (mechanics) over a short time period * Impact, Texas, a town in Taylor County, Texas, US Science and technology * Impact crater, a meteor crater caused by an impact event * Impac ...
into the Nuna supercontinent from a
bolide A bolide is normally taken to mean an exceptionally bright meteor, but the term is subject to more than one definition, according to context. It may refer to any large crater-forming body, or to one that explodes in the atmosphere. It can be a ...
approximately in diameter that occurred 1.849 billion years ago in the
Paleoproterozoic The Paleoproterozoic Era (;, also spelled Palaeoproterozoic), spanning the time period from (2.5–1.6  Ga), is the first of the three sub-divisions (eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest era of the Earth's ...
era. Debris from the impact was scattered over an area of thrown more than ; and
ejecta Ejecta (from the Latin: "things thrown out", singular ejectum) are particles ejected from an area. In volcanology, in particular, the term refers to particles including pyroclastic materials (tephra) that came out of a volcanic explosion and magma ...
— rock fragments ejected by the impact — have been found as far away as
Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...
.Jirsa, M.A. (2008) and Retzler, A.J. (2020
"Ancient Meteorite Deposit in Minnesota"
'' Minnesota Geological Survey ''
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 round crater that the
bolide A bolide is normally taken to mean an exceptionally bright meteor, but the term is subject to more than one definition, according to context. It may refer to any large crater-forming body, or to one that explodes in the atmosphere. It can be a ...
originally created. Subsequent geological processes have deformed the crater into the current smaller oval shape. Sudbury Basin is the third-largest crater on Earth, after the
Vredefort impact structure The Vredefort impact structure is the largest verified impact structure on Earth. The crater, which has since been eroded away, was around across when it was formed. The remaining structure, comprising the deformed underlying bedrock, is loca ...
in
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
, and the
Chicxulub crater The Chicxulub crater () is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is offshore near the community of Chicxulub, after which it is named. It was formed slightly over 66 million years ago when a large a ...
under
Yucatán Yucatán (, also , , ; yua, Yúukatan ), officially the Free and Sovereign State of Yucatán,; yua, link=no, Xóot' Noj Lu'umil Yúukatan. is one of the 31 states which comprise the political divisions of Mexico, federal entities of Mexico. I ...
,
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
. Geochemical evidence suggests that the impactor was likely a
chondrite A chondrite is a stony (non-metallic) meteorite that has not been modified, by either melting or differentiation of the parent body. They are formed when various types of dust and small grains in the early Solar System accreted to form primi ...
asteroid or a comet with a chondritic component.


Structure

The full extent of the Sudbury Basin is long, wide and deep, although 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 a
suevite Suevite is a rock consisting partly of melted material, typically forming a breccia containing glass and crystal or lithic fragments, formed during an impact event. It forms part of a group of rock types and structures that are known as imp ...
and sedimentary package composed of the Onaping (fallback
breccia Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of di ...
s), Onwatin, and Chelmsford Formations in stratigraphic succession. Footwall rocks, associated with the impact event, consist of Sudbury Breccia (
pseudotachylite Pseudotachylyte (sometimes written as pseudotachylite) is an extremely fine-grained to glassy, dark, cohesive rock occurring as veinsTrouw, R.A.J., C.W. Passchier, and D.J. Wiersma (2010) ''Atlas of Mylonites- and related microstructures.'' Sprin ...
), footwall breccia, radial and concentric quartz dioritic breccia dikes (polymict impact melt breccias), and the discontinuous sub layer. Because considerable erosion has occurred since the Sudbury event, an estimated 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 Mega years): # formation of the Sudbury Igneous Complex (1849 Ma) #
Penokean orogeny The Penokean orogeny was a mountain-building episode that occurred in the early Proterozoic about 1.86 to 1.83 billion years ago, in the area of Lake Superior, North America. The core of this orogeny, the Churchill Craton, is composed of terranes ...
(1890–1830 Ma) #
Mazatzal orogeny The Mazatzal orogeny was an orogenic event in what is now the Southwestern United States from 1650 to 1600 Mya in the Statherian Period of the Paleoproterozoic. Preserved in the rocks of New Mexico and Arizona, it is interpreted as the collisi ...
(1700–1600 Ma) #
Grenville orogeny The Grenville orogeny was a long-lived Mesoproterozoic mountain-building event associated with the assembly of the supercontinent Rodinia. Its record is a prominent orogenic belt which spans a significant portion of the North American continent, ...
(1400–1000 Ma) #
Lake Wanapitei Lake Wanapitei (also known as Lake Wahnapitae) occupies a meteorite crater in Sudbury, Ontario, Canada. It is located near the much larger Sudbury meteorite crater but they are not related. The crater is in diameter and the age is estimated to ...
impact (37 Ma)


Origin

Some 1.8 billion years of weathering and deformation made it difficult to prove that 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 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 cone Shatter cones are rare geological features that are only known to form in the bedrock beneath meteorite impact craters or underground nuclear explosions. They are evidence that the rock has been subjected to a shock with pressures in the rang ...
s 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 the concentration and distribution of
siderophile elements The Goldschmidt classification, developed by Victor Goldschmidt (1888–1947), is a geochemical classification which groups the chemical elements within the Earth according to their preferred host phases into lithophile ( rock-loving), siderophil ...
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 Temagami Magnetic Anomaly, also called the Temagami Anomaly or the Wanapitei Anomaly, is a magnetic anomaly resulting from a large buried geologic structure in the Canadian Shield near Temagami, Ontario, Canada. It stretches from Lake Wanapit ...
, the
Lake Wanapitei Lake Wanapitei (also known as Lake Wahnapitae) occupies a meteorite crater in Sudbury, Ontario, Canada. It is located near the much larger Sudbury meteorite crater but they are not related. The crater is in diameter and the age is estimated to ...
impact crater, the western end of the
Ottawa-Bonnechere Graben The Ottawa-Bonnechere Graben (also known as the Ottawa Graben) is a geological structure that coincides with a wide topographic depression extending from near Montréal through Ottawa. It is part of the Saint Lawrence rift system that also inclu ...
, the
Grenville Front Tectonic Zone The Grenville Front Tectonic Zone is a geological feature in Eastern Canada that separates the Superior craton from rocks of the Grenville orogeny. It is a large tectonic zone of the Canadian Shield, extending from the northern shore of Lake Huron t ...
and the eastern end of the Great Lakes Tectonic Zone, although none of the structures are directly related to each other in the sense of resulting from the same geological processes.


Mining

The large impact crater filled with
magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...
containing
nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...
,
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
,
palladium Palladium is a chemical element with the symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas, which was itself na ...
,
gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile met ...
, the
platinum group The platinum-group metals (abbreviated as the PGMs; alternatively, the platinoids, platinides, platidises, platinum group, platinum metals, platinum family or platinum-group elements (PGEs)) are six noble, precious metallic elements clustered t ...
and other
metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...
s. This magma formed into
pyrrhotite Pyrrhotite is an iron sulfide mineral with the formula Fe(1-x)S (x = 0 to 0.2). It is a nonstoichiometric variant of FeS, the mineral known as troilite. Pyrrhotite is also called magnetic pyrite, because the color is similar to pyrite and it is ...
,
chalcopyrite Chalcopyrite ( ) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mo ...
and
pentlandite Pentlandite is an iron–nickel sulfide with the chemical formula . Pentlandite has a narrow variation range in Ni:Fe but it is usually described as having a Ni:Fe of 1:1. It also contains minor cobalt, usually at low levels as a fraction of wei ...
rocks, as well as
cubanite Cubanite is a copper iron sulfide mineral that commonly occurs as a minor alteration mineral in magmatic sulfide deposits. It has the chemical formula CuFe2S3 and when found, it has a bronze to brass-yellow appearance. On the Mohs hardness scale, ...
and
magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With the ...
. In 1856 while surveying a baseline westward from
Lake Nipissing Lake Nipissing (; french: lac Nipissing, oj, Gichi-nibiinsing-zaaga’igan) is a lake in the Canadian province Within the geographical areas of Canada, the ten provinces and three territories are sub-national administrative divisions under ...
, 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 Creighton Mine is an underground nickel, copper, and platinum-group elements (PGE) mine. It is presently owned and operated by Vale Limited (formerly known as INCO) in the city of Greater Sudbury, Ontario, Canada. Open pit mining began in 1901, ...
. The area was examined by Alexander Murray of the
Geological Survey of Canada The Geological Survey of Canada (GSC; french: Commission géologique du Canada (CGC)) is a Canadian federal government agency responsible for performing geological surveys of the country, developing Canada's natural resources and protecting the en ...
, who confirmed "the presence of an immense mass of magnetic trap". Due to the then-remoteness of the Sudbury area, Salter's discovery did not have much immediate effect. The construction of the
Canadian Pacific Railway The Canadian Pacific Railway (french: Chemin de fer Canadien Pacifique) , also known simply as CPR or Canadian Pacific and formerly as CP Rail (1968–1996), is a Canadian Class I railway incorporated in 1881. The railway is owned by Canadi ...
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 The Murray Mine is a defunct nickel and copper mine in Greater Sudbury, Ontario. It was the site of the original ore discovery that led to the launch of mining operations in the Sudbury Basin area. The Murray Mine was discovered in August 1883 ...
site, named by owners William and Thomas Murray. The Vermillion Mine, which 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 the Holloway recommendations were in line with the agitations of Aeneas McCharles a 19th-century prospector and early mine owner.Bemocked of Destiny : The Actual Struggles and Experiences of a Canadian Pioneer, and the Recollections of a Lifetime / By Aeneas McCharles. Toronto : William Briggs, 1908 As a result of these metal deposits, the Sudbury area is one of the world's major
mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic via ...
communities, and has fathered
Vale Inco Vale Canada Limited (formerly Vale Inco, CVRD Inco and Inco Limited; for corporate branding purposes simply known as "Vale" and pronounced in English) is a wholly owned subsidiary of the Brazilian mining company Vale. Vale's nickel mining and ...
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.


Agriculture

Due to the high mineral content of its soil, the floor of the basin is among the best
agricultural Agriculture or farming is the practice of cultivating Plant, plants and livestock. Agriculture was the key development in the rise of Sedentism, sedentary human civilization, whereby farming of Domestication, domesticated species created food ...
land in
Northern Ontario Northern Ontario is a primary geographic and quasi-administrative region of the Canadian province of Ontario, the other primary region being Southern Ontario. Most of the core geographic region is located on part of the Superior Geological Provi ...
, with numerous
vegetable Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still commonly used and is applied to plants collectively to refer to all edible plant matter, including the flowers, fruits, stems, ...
,
berry A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit, although many pips or seeds may be present. Common examples are strawberries, raspb ...
, and
dairy A dairy is a business enterprise established for the harvesting or processing (or both) of animal milk – mostly from cows or buffaloes, but also from goats, sheep, horses, or camels – for human consumption. A dairy is typically located on ...
farms located in the valley. However, because of its northern latitude, it is not as productive as agricultural lands in the southern portion of the province. Accordingly, the region primarily supplies products for consumption within Northern Ontario, and is not a major food exporter.


Astronaut training

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...
used the site to train the
Apollo astronauts As part of the Apollo program by NASA, 24 astronauts flew 9 missions to the Moon between December 1968 and December 1972. During six successful two-man landing missions, 12 men walked on the lunar surface, six of whom drove Lunar Roving Vehicl ...
in recognizing rocks formed as the result of a very large impact, such as
breccia Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of di ...
s. Those who used this training on the Moon include
Apollo 15 Apollo 15 (July 26August 7, 1971) was the ninth crewed mission in the United States' Apollo program and the fourth to Moon landing, land on the Moon. It was the first List of Apollo missions#Alphabetical mission types, J mission, with a ...
's
David Scott David Randolph Scott (born June 6, 1932) is an American retired test pilot and NASA astronaut who was the seventh person to walk on the Moon. Selected as part of the third group of astronauts in 1963, Scott flew to space three times and c ...
and
James Irwin James Benson Irwin (March 17, 1930 â€“ August 8, 1991) was an American astronaut, aeronautical engineer, test pilot, and a United States Air Force pilot. He served as Apollo Lunar Module pilot for Apollo 15, the fourth human lunar landing. ...
,
Apollo 16 Apollo 16 (April 1627, 1972) was the tenth crewed mission in the United States Apollo space program, administered by NASA, and the fifth and penultimate to land on the Moon. It was the second of Apollo's " J missions", with an extended sta ...
's
John Young John Young may refer to: Academics * John Young (professor of Greek) (died 1820), Scottish professor of Greek at the University of Glasgow * John C. Young (college president) (1803–1857), American educator, pastor, and president of Centre Col ...
and
Charlie Duke Charles Moss Duke Jr. (born October 3, 1935) is an American former astronaut, United States Air Force (USAF) officer and test pilot. As Lunar Module pilot of Apollo 16 in 1972, he became the tenth and youngest person to walk on the Moon, at ag ...
, and
Apollo 17 Apollo 17 (December 7–19, 1972) was the final mission of NASA's Apollo program, the most recent time humans have set foot on the Moon or traveled beyond low Earth orbit. Commander Gene Cernan and Lunar Module Pilot Harrison Schmitt walked on ...
's
Gene Cernan Eugene Andrew Cernan (; March 14, 1934 â€“ January 16, 2017) was an American astronaut, naval aviator, electrical engineer, aeronautical engineer, and fighter pilot. During the Apollo 17 mission, Cernan became the eleventh human being to ...
and
Jack Schmitt Harrison Hagan Schmitt (born July 3, 1935) is an American geologist, retired NASA astronaut, university professor, former U.S. senator from New Mexico, and the most recent living person—and only person without a background in military aviationâ ...
. Notable geologist instructors included William R. Muehlberger.


See also

* Economic geology *
Geology of Ontario The geology of Ontario consists of the study of the rock formations in the most populated province of Canada. Ontario has some of the oldest rocks on Earth. It is made up of ancient Precambrian igneous and metamorphic rock and overlain by younger ...
*
List of impact craters on Earth This list of impact craters on Earth contains a selection of the 190 confirmed craters given in the Earth Impact Database as of 2017. To keep the lists manageable, only the largest craters within a time period are included. Alphabetical lists f ...
*
List of possible impact structures on Earth This is a list of possible impact structures on Earth. More than 130 geophysical features on the surface of the Earth have been proposed as candidate sites for impact events by appearing several times in the literature and/or being endorsed by the ...


References


External links


Earth Impact Database


*
Aerial Exploration of the Sudbury Impact StructureSudbury Impact Structure
at NASA
Earth Observatory NASA Earth Observatory is an online publishing outlet for NASA which was created in 1999. It is the principal source of satellite imagery and other scientific information pertaining to the climate and the environment which are being provided by NA ...
, September 20, 2021 {{Impact cratering on Earth Impact craters of Ontario Proterozoic impact craters Precambrian Canada Geology of Greater Sudbury Landforms of Greater Sudbury Economic geology