The Charlevoix impact structure is a large eroded
meteorite
A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or Natural satellite, moon. When the ...
impact structure
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 surface ...
in the
Charlevoix
Charlevoix ( , ) is a cultural and natural region in Quebec, on the north shore of the Saint Lawrence River as well as in the Laurentian Mountains area of the Canadian Shield. This dramatic landscape includes rolling terrain, fjords, headlands ...
region of
Quebec
Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirtee ...
, Canada.
Only part of the impact structure is exposed at the surface, the rest lying beneath the
Saint Lawrence River
The St. Lawrence River (french: Fleuve Saint-Laurent, ) is a large river in the middle latitudes of North America. Its headwaters begin flowing from Lake Ontario in a (roughly) northeasterly direction, into the Gulf of St. Lawrence, connectin ...
.
Description
The original impact structure is estimated to have been in
diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...
and the age of the impact is estimated to be 450 ± 20 million years (
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...
to
Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...
age).
[Schmieder, M., Shaulis, B.J., Lapen, T.J., Buchner, E. and Kring, D.A., 2019. ''In situ U–Pb analysis of shocked zircon from the Charlevoix impact structure, Québec, Canada.'' ''Meteoritics & Planetary Science.'' 54(8) pp. 1808-1827.] The projectile was probably a stony asteroid, at least in diameter, and weighing an estimated . The
Mont des Éboulements
Mont may refer to:
Places
* Mont., an abbreviation for Montana, a U.S. state
* Mont, Belgium (disambiguation), several places in Belgium
* Mont, Hautes-Pyrénées, a commune in France
* Mont, Pyrénées-Atlantiques, a commune in France
* Mont, Saà ...
, situated in the exact centre of the impact structure, is interpreted as the central uplift, a consequence of elastic rebound.
[Interpretation Centre, Parc national des Grands-Jardins, Charlevoix] The impact structure is classified as a
multi-ringed basin
A multi-ringed basin (also a multi-ring impact basin) is not a simple bowl-shaped crater, or a peak ring crater, but one containing multiple concentric topographic rings; a multi-ringed basin could be described as a massive impact crater, surroun ...
with a central uplift.
The impact origin of Charlevoix impact structure was first realized in 1965 after the discovery of many
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 in the area. Other evidence for impact includes
planar deformation features
Planar deformation features, or PDFs, are optically recognizable microscopic features in grains of silicate minerals (usually quartz or feldspar), consisting of very narrow planes of glassy material arranged in parallel sets that have distinct orie ...
(PDFs) in
quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...
and
feldspar
Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldsp ...
grains.
In contrast to the surrounding craggy
Laurentian Mountains
The Laurentian Mountains ( French: ''Laurentides'') are a mountain range in southern Quebec, Canada, north of the St. Lawrence River and Ottawa River, rising to a highest point of at Mont Raoul Blanchard, northeast of Quebec City in the Laurentid ...
, the impact structure is relatively smooth and flat, which has facilitated human settlement. Today, 90% of the people of Charlevoix live within this impact structure.
References
External links
Earth Impact DatabaseSatellite image of the region(from Google Maps)
Aerial Exploration of the Charlevoix Structure
{{Authority control
Impact craters of Quebec
Ordovician impact craters
Silurian impact craters
Ordovician Quebec
Silurian Quebec
.impact structure