Manicouagan crater
Encyclopedia
The Manicouagan Crater is one of the oldest known impact crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

s and is located primarily in Manicouagan Regional County Municipality
Manicouagan Regional County Municipality, Quebec
Manicouagan is a Regional County Municipality in the Côte-Nord region of Quebec, Canada. It is located on the north shore of the Saint Lawrence River with its seat in Baie-Comeau...

 in the Côte-Nord
Côte-Nord
Côte-Nord is the second largest administrative region by land area in Quebec, Canada, after Nord-du-Québec...

 region of Québec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....

, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, about 300 km (186.4 mi) north of the city of Baie-Comeau. Its northernmost part is located in Caniapiscau Regional County Municipality
Caniapiscau Regional County Municipality, Quebec
Caniapiscau is a regional county municipality in northeastern Quebec, Canada. The regional county municipality seat is Fermont. It is located in the northwest corner of the Côte-Nord region of Quebec. It has a land area of and a 2006 census population of 3,948 inhabitants, two-thirds of whom lived...

. It is thought to have been caused by the impact of a 5 km (3 mi) diameter asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

 about 215.5 million years ago (Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

 Period). It was once thought to be associated with the end-Carnian
Carnian
The Carnian is the lowermost stage of the Upper Triassic series . It lasted from about 228.7 till 216.5 million years ago . The Carnian is preceded by the Ladinian and is followed by the Norian...

 extinction event
Extinction event
An extinction event is a sharp decrease in the diversity and abundance of macroscopic life. They occur when the rate of extinction increases with respect to the rate of speciation...

, but the Carnian-Norian boundary is now known to be much older, around 228 million years ago.

The crater is a multiple-ring structure about 100 kilometre, with its 70 kilometre diameter inner ring its most prominent feature; it contains a 70 kilometre diameter annular lake, the Manicouagan Reservoir
Manicouagan Reservoir
Manicouagan Reservoir is an annular lake in central Quebec, Canada. The lake covers an area of 1,942 km², and its eastern shore is accessible via Route 389. The island in the centre of the lake is known as René-Levasseur Island, and its highest point is Mount Babel...

, surrounding an inner island plateau, René-Levasseur Island
René-Levasseur Island
René-Levasseur Island is a large island in the center of Lake Manicouagan in Quebec, Canada. Its highest peak is Mount Babel, at 952 m . With a total area of 2,020 km² , the island is larger in terms of area than the lake in which it is situated...

. It is the earth's fifth largest confirmed impact crater.

Hypothetical multiple impact event

It has been suggested that the Manicouagan crater may have been part of a hypothetical multiple impact event which also formed the Rochechouart crater
Rochechouart crater
Rochechouart is an impact crater in France.The crater diameter is still under study but is expected to be about . Its most recent age estimate is 201 ±2 million years ago, placing it close to Triassic-Jurassic boundary. Since then the crater has been deeply eroded, and no trace of its original...

 in France, Saint Martin crater
Saint Martin crater
Saint Martin is an impact crater in Manitoba, Canada.It is in diameter and its age is estimated at 220 ± 32 million years . The crater is not exposed at the surface.-Hypothetical multiple impact event:...

 in Manitoba
Manitoba
Manitoba is a Canadian prairie province with an area of . The province has over 110,000 lakes and has a largely continental climate because of its flat topography. Agriculture, mostly concentrated in the fertile southern and western parts of the province, is vital to the province's economy; other...

, Obolon' crater
Obolon' crater
Obolon' crater is a diameter buried meteorite impact crater situated about southeast of Kiev in Ukraine .The site has been drilled, which revealed the presence of shocked minerals and impact melt rock; the high chlorine content of the latter suggesting that the area was covered by shallow sea at...

 in Ukraine
Ukraine
Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...

, and Red Wing crater
Red Wing crater
Red Wing or Red Wing Creek structure is a meteor crater located inMcKenzie County, North Dakota, about southwest of Watford City, North Dakota, United States....

 in North Dakota
North Dakota
North Dakota is a state located in the Midwestern region of the United States of America, along the Canadian border. The state is bordered by Canada to the north, Minnesota to the east, South Dakota to the south and Montana to the west. North Dakota is the 19th-largest state by area in the U.S....

. Geophysicist David Rowley of the University of Chicago
University of Chicago
The University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...

, working with John Spray of the University of New Brunswick
University of New Brunswick
The University of New Brunswick is a Canadian university located in the province of New Brunswick. UNB is the oldest English language university in Canada and among the first public universities in North America. The university has two main campuses: the original campus founded in 1785 in...

 and Simon Kelley of the Open University
Open University
The Open University is a distance learning and research university founded by Royal Charter in the United Kingdom...

, discovered that the five craters formed a chain, indicating the breakup and subsequent impact of an asteroid or comet, similar to the well observed string of impacts of Comet Shoemaker-Levy 9
Comet Shoemaker-Levy 9
Comet Shoemaker–Levy 9 was a comet that broke apart and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of solar system objects. This generated a large amount of coverage in the popular media, and the comet was closely observed by...

 on Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

 in 1994.

Kelley had developed a technique to precisely date impact craters, using laser argon-argon dating
Argon-argon dating
Argon-argon dating is a radiometric dating method invented to supersede potassium-argon dating in accuracy. The older method required two samples for dating while the newer method requires only one...

 of the glass formed by the impacts, and cited stratigraphic evidence to support an older age of 215 ± 25 Myr (Late Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

). He and Kelley sought Rowley's help to determine how the craters were aligned when the impacts occurred, since—due to plate tectonics
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...

—the locations have moved large distances in the intervening 214 million years. Three of the craters—Rochechouart, Manicouagan and Saint Martin—formed a 5000 km (3,106.9 mi) chain at latitude 22.8° N, while Obolon' and Red Wing lay on identical declination paths with Rochechouart and Saint Martin respectively. All of the craters had previously been known and studied, but their paleoalignment had never before been demonstrated. Rowley has said that the chance that these craters could be aligned like this due to chance are nearly zero.
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