Meteorite crater refers to the crater formed by outer meteorite (or meteorite) hitting the ground at a high speed and violently, which is mostly circular and elliptical in shape, or forms radial and circular structures. It is called meteorite impact crater, also called meteorite crater, or meteorite crater.The inner wall of the crater is steep and the outer edge is gentle. In larger craters, there are often prominent central peaks, and there are often breccias and highly metamorphic minerals in the crater.
Chinese name
Meteorite crater
Foreign name
meteorite crater
Discipline
astronomy
Time
Billions of years
Form
Round, oval
Quantity
About 180 seats
Definition
Formed by outer meteorite (or meteorite) hitting the ground at high speed
The earth has been impacted by meteorites many times in its development history, butvolcanoSome meteorite craters have been eliminated or covered by geological movement, weathering, rain erosion and other weather changes.There are about 180 intact craters distributed on the surface of the earth.Most of them are found in ancient and stable continental areas, which are geologically stable and have a history of billions of years.The largest meteorite crater - Fort Fried meteorite crater in South Africa,diameter300 kilometers, while Canada'sSudburyMeteorite craters are 250 kilometers in diameter, and they are also the oldest ones with a history of 2 billion years and 1.85 billion years respectively.The age of the crater is not directly related to its diameter.For example,MexicoThe impact crater on the Yucatan Peninsula is 180 kilometers in diameter and 65 million years old.Meteorite craters with a long history like this are often eroded in large areas and can only be leftBedrockOnshock waveForm.[1]
characteristic
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1. There is a bowl shape on the surface of the large meteorite crater;
2．stratumCompared with its surroundings, it is inverted:
5. It can be foundMeteoriteFragments and so on.[1]
morphological structure
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Meteorite craters are divided into simple and complex ones, and their morphology and structure are shown in the Meteorite Crater Schematic Diagram.With the increase of meteorite size, the probability of falling to the earth every year is also getting lower and lower, but a larger size means that the potential danger of meteorite impact is getting greater and greater.According to the data records of meteorite falling in the past 200 years and the established theoretical model, about two meteorites weighing 1000 kg fall on the earth every year, and one meteorite weighing 100000 kg falls on the earth every 100 years.[1]
Schematic Diagram of Meteorite Crater
A meteorite crater is composed of crater lip, crater wall and central uplift. The crater lip is the uplift around the crater. The breccia is formed by the accumulation of materials splashed out after the meteorite impact. The crater wall is generally steep. It is formed after a large amount of materials splashed out after the meteorite impact. There are many vertical cracks on the crater wall, and some collapsed materials are accumulated below the grooves. If the meteorite crater is formed for a long time,The inclination of the pit wall will become slower, which will expand the area of the pit.There is a central uplift in the center of the craterGravelThese gravels are part of the splashes on the pit wall when the explosion occurs.
Depth of crater/diameter=1/5~1/6, after the pit wall collapses and slows down, this ratio can be changed to 1/7~1/8.The materials that can be splashed in the crater and theweightThe ratio is 160/1, if you pressvolumeIt is calculated as (170~200)/1.[2]
Matter formation
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After the formation of the meteorite crater, not only a large number of breccias are produced, but also the mineral composition changes, such asquartzAfter the meteorite strike, there will be many small particles and many shapesCoesite, hyperquartz and silica glassPyroquartz, quadrangularzirconWill become square biconicalClinozoite。Many minerals appear wavy extinction,SanidineBecomes spherulite inX-rayIn the analysis, it can be seen that the crystal structure is damaged, and there is "starvation" or slight mosaic at the edge of the crystal.Shi YinghefeldsparFormation of eutectic vermiculite, etc.This is also an important feature to distinguish meteorite impact breccia from general breccia.[2]
The famous meteorite crater
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Arizona, USA
U.S.AArizonaOfBalingerMeteorite crater "has a diameter of about 1240 meters and an average depth of 180 meters. It is called" the first meteorite crater confirmed by scientists in the world ". Scientists used to believe that it is aExtinct volcano。Until 1903, American mining engineer Balinger proposed that it was a meteorite crater formed by a meteorite hitting the earth about 50000 years ago, which was confirmed by scientists. Later, the crater was named "Balinger meteorite crater".Balinger inferred from the surrounding debris that this is probably rich inironAnd bought the property right of this land.
The meteorite crater was finally confirmed by scientists thanks to the investigation of astronomer Sumek.In the 1950s, due to the discovery of Sumek LevycometThe famous Sumek has visited here many times and found that the landform here is similar to that of the United StatesUnderground nuclear testThe landform of the site is surprisingly consistent.For example, their rocks are melted into glass under high temperaturerock stratumThey were overturned under the huge impact.Sumek's inspiration from this crater has become a widely accepted theoretical model of the "collision between heaven and earth" in the scientific community.[1]
Ballinger Crater
Northern Australia
Northern AustraliaGosses Bluff The crater looks very much in line with its age of about 142 million years.There is a 150 meter high mountain in the middle of the rugged and beautiful meteorite crater, pointing directly into the sky.The original craterdiameterIt is 22km long, and its diameter is reduced to 5km due to damage.
Anshan City, Liaoning Province
Liaoning Xiuyan Crater is the first meteorite crater preliminarily confirmed in China, located in Liaoning Province in the north of Liaodong PeninsulaAnshan CityXiuyan Manchu Autonomous County.The survey shows that the crater is bowl shaped, with a diameter of 1800 meters and a depth of about 150 meters.It is estimated that the impact event occurred 50000 years ago and evolved into a bowl shaped depression about 39000 years ago.
The Canadian Pingualuit crater is located in theAngawa PeninsulaIt was found in the mid 1940s, with a diameter of 3.44 kilometers, and is known as the "Eye of Nunavik" by local people.Pingualuit crater was formed about 1.4 million years ago.Because of rain and snow, a lake appeared in the crater.[1]
Lunar crater
On September 1, 2023, the National Aeronautics and Space Administration (NASA) announced on its official website that its "Lunar Reconnaissance Orbiter" (LRO) had photographed a new "meteorite crater" on the surface of the moon, which was presumably caused by the impact of the Russian "Lung-25" probe.[3]
On April 21, 2024, the 1:2500000 Full Moon Geological Map identified and marked 12341 impact craters in the whole moon.[4-5]
1: 2.5 million full moon geological map
Meteorite crater storing oil and natural gas
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There is a large amount of breccia in the crater for accumulationpetroleumandnatural gasOfReservoirThis is the basic condition for meteorite craters to store oil and natural gas. If there are rich oil and gas sources and good caprocks, they can be formedOil and gas reservoirorOil and gas fields。statesideTexasA 13 km diameter meteorite crater was found, and an exploration well was drilled on the crater lip, with a daily gas production of 2800 ×
m³，It is a high-yield gas field.Wellston, North AmericabasinMedium,North DakotaA meteorite crater with a daily gas output of 90m ³ was found.With the deepening of exploration, more meteorite crater oil fields are expected to be found.[2]
