There are very few impact craters or, as they are called, multi-ring craters on Earth. They are more typical for other planets in the solar system. The most famous crater of this kind is Valhalla, located on Callisto, a moon of Jupiter. And on Earth, all traces of the Earth’s meetings with celestial wanderers, as a rule, are destroyed by erosion and tectonic processes.

crater Valhalla on Callisto

So, craters on the surface(this is the topic of the article) indicate repeated collisions of asteroids with our planet (about 175 confirmed meteorite craters are known on Earth). Millions, and in some cases billions of years of erosion do not allow us to accurately determine the size of fallen celestial bodies, but the largest of them are generally known.

Now, in the database compiled by the Siberian Center for the Study of Global Disasters, there are more than 800 geological formations that, with varying degrees of certainty, can be considered meteorite craters. The largest have a diameter of more than a thousand kilometers, and the smallest are measured in tens of meters. In fact, apparently, there are many more meteorite wounds on the Earth’s body, but not all of them have been discovered yet.

Wilkes Land Crater

Wilkes Land Crater is a geological formation located under the ice sheet of Antarctica, in the Wilkes Land region, with a diameter of about 500 km. It is believed that this is a giant meteorite crater.

Because the structure lies beneath the Antarctic Ice Sheet, direct observations are not yet possible. If this formation is indeed an impact crater, then the meteorite that created it was about 6 times larger than the meteorite that created the Chicxulub crater, which is believed to have caused the mass extinction at the Cretaceous-Cenozoic boundary (Cretaceous-Paleogene extinction).

According to scientists, the collision of the Earth with this meteorite caused the Permian-Triassic extinction event about 250 million years ago. The same one that gave the green light to dinosaurs and marked the beginning of the era of their prosperity on the planet. Up to 90 percent of all living creatures have become extinct! If civilization had existed at that time, it would, without a doubt, have perished. Well, with mollusks and primitive fish they somehow survived. Evolution went even faster, after which mammals appeared...

The size and location of the crater also suggests that its formation caused the breakup of the supercontinent Gondwana, creating a tectonic rift that displaced Australia north.

“The crater on the Yucatan Peninsula, the appearance of which 65 million years ago put an end to the history of giant reptiles, is approximately two to three times smaller than the Antarctic one,”

Researchers note.

Wilkes Land, located between 150 and 90 east, occupies approximately 1/5 of the entire area of ​​Antarctica. Here, outlet and shelf glaciers make it difficult for research teams to move. In the sea offshore opposite Wilkes Land is the South Magnetic Pole. Its approximate coordinates are 65 S. and 140 E.

Antarctica - view from space

Vredefort Crater

Vredefort Crater is an impact crater on Earth, located 120 kilometers from Johannesburg, South Africa. This crater with a diameter of about 300 kilometers occupies 6% of the area of ​​South Africa, which makes it the largest on the planet (not counting the unexplored probable crater of Wilkes Land with a diameter of 500 kilometers in Antarctica), and therefore the crater can only be observed on satellite images (unlike small craters that can be “covered” with a glance).

Named after the city of Vredefort located inside the crater (there are even three cities and a lake in the crater!). In 2005 it was included in the list of UNESCO World Heritage Sites.

The meteorite, from the fall of which one of the main attractions of the Republic of South Africa was formed, changed the landscape of the Earth more than all other meteorites. The asteroid was one of the largest ever to come into contact with the planet after its formation; According to modern estimates, its diameter was about 10, perhaps 15 kilometers.

It was born more than 2 billion years ago. And it is one of the oldest on Earth. It was only 300 million behind the appearance of the Suoyarvi crater, which is located in Russia.

There is a hypothesis that the energy released as a result of the impact greatly changed the course of evolution of single-celled organisms.

"Kara Crater"

And in Russia, the largest impact crater is the Kara crater, which is located on the Yugorsky Peninsula, on the shore of Baydaratskaya Bay...

The territory of Russia is so large that it is here that scientists find most of the largest craters in the world. Calculations by Professor V.L. Masaitis and M.S. Mashchak (St. Petersburg) show that on the territory of Russia and neighboring countries there should be 1280 astroblemes more than 1 km in diameter, not erased by erosion and exposed on the surface. We currently know only 42 meteorite craters in this area (including small ones and those covered by younger sediments).

So, do you think the Tunguska meteorite was great? What about a meteorite that left behind a crater a hundred in diameter? :)

Kara crater with a diameter of about 65 km – 7th largest impact crater in the world, which was formed as a result of the fall of a meteorite about 70 million years ago, which suggests its connection with the Great Mesozoic Extinction - according to researchers, the Kara impact event led to a global natural crisis: the climate on our planet became colder, mass extinction of organisms began, including dinosaurs.

It is also possible to identify a chain of impact structures of the same age (about 75-65 million years) from one meteorite swarm. This chain begins in Ukraine - the Gusevsky craters (3 km in diameter) and Boltyshsky, located to the north (25 km). In the northern Urals, this chain continues in the form of the Kara (62 km) and Ust-Karsk (>60 km) astroblemes; further, the flight path of the fireballs passed along the Northern coast. The Arctic Ocean (where traces of the fall have not yet been established), then over the Bering Sea (where the fall of a large asteroid supposedly took place) and, finally, ended with the formation of the largest Chicxulub astrobleme in the chain (180 km) on the Yucatan Peninsula and the Gulf of Mexico.

However, the figures for the Kara diameter are not yet accurate: there is a theory that the waters of the Kara Sea hide the true dimensions of the crater - presumably no less than 120 kilometers in diameter.

The crater is located in the foothills of the Pai-Khoi ridge, 15 km west of the Kara River. In relief it is an elongated depression open to the sea. The Kara crater is filled with rock fragments formed during the explosion, partially melted and frozen in the form of a glassy mass.

The impactites of the Kara structure also contain diamonds. During the impact, coal turned into a high-density X-ray amorphous polymer of carbon and into crystalline diamond - as a result of the impact, sea water was thrown back tens, hundreds of kilometers at the site of the current Ust-Kara village. And at the bottom a funnel with a diameter of 65 km formed - the Kara crater. Part of the meteorite fragments, having received a second escape velocity, went back into space. The rocks at the site where the meteorite fell were partially melted. Under the cover of the sea and marine silt, the melt slowly solidified, turning into glass, cementing the fragments. Under the influence of ultra-high explosive pressures, the texture of minerals changed. Today, the surface of the crater is a marshy-lake plain, rising above sea level.

There are two points of view on the size of this structure. According to the first, it consists of two craters - Karsky with a diameter of 60 km and 25 km Ust-Karsky, partially covered by the sea. The main part of the rocks in the form of fragments of various sizes - from dust-like to kilometers long - was thrown out of the crater in the form of an explosive column. The rocks consisted of allogeneic breccias, i.e., undisplaced impactites. Under the cover of sea water and silt, the impact melt slowly solidified, turning into glass, cementing the fragments. This is how suevites were formed.

However, there are a number of facts that suggest that the Kara crater had a diameter of 110 - 120 kilometers, and the Ust-Kara crater does not exist. These mainly include the presence of suvites and breccias on the river. Syad'ya-Yakha and the absence of anomalous gravitational and magnetic fields in the area of ​​the Ust-Kara crater, which is unusual, since even much smaller craters are well expressed in geophysical fields. It is assumed that after the formation of the crater, it was washed out (eroded), as a result of which only the central 60-kilometer basin was preserved, and the outcrops of impactites on the shore, attributed to the Ust-Kara crater, are the remnants of the impact strata that once filled the entire crater that survived the erosion. Zyuvites and authigenic breccias emerging at a distance of 55 km from the center of the crater in the valley of the river. Syadma-Yakha are also the remains of a crater.

The meteorite nature of the Kara Depression was proven by the Russian scientist M.A. Maslov through gravimetric, magnetometric and seismic work, as well as analyzes of rocks obtained by drilling wells.

Travelers who want to see the amazing crater will have to go through a difficult journey; they can only get directly to the crater by private helicopter. For researchers, the Kara crater continues to be the most important object; valuable diamond deposits have been discovered on its territory. The size of some of them reaches 4 mm, and the total content of precious stones in the rock reaches 50 carats per ton.

The most famous (and hypothetical) meteorite craters

Bermudian. Diameter: 1250 km. Geophysical anomalies caused by the impact of a meteorite impact may explain the Bermuda Triangle effect. However, the meteorite nature of the depression has not been fully proven.

Ontong Java. Diameter: 1200 km. Age: approximately 120 million years. The crater is underwater and very poorly studied.

Lass Antilles. Diameter 950 km. According to one hypothesis, the main part of the Caribbean Sea is a meteorite crater.

Bangui. Diameter: 810 km. Age: 542 million years. The largest geophysical anomaly in Africa. According to one version, it occurred as a result of an impact from a cosmic body.

Pribalkhash-Iliysky. Diameter: 720 km. Identified from satellite images and analysis of geophysical fields.

Ural. Diameter: 500 km. There is a hypothesis that deposits of gold, uranium and other minerals in the Urals are associated with the fall of a giant meteorite.

Chesterfield. Diameter: 440 km. Satellite images reveal a series of rings with a single center. Looks like a meteorite.

South Caspian. Diameter: 400 km. The idea that the Caspian Sea was formed as a result of the impact of a giant celestial body was put forward by Galileo.

Vredefort. Diameter: 300 km. Age: approximately 2 billion years. The largest of the craters, whose meteorite nature is fully proven. The energy from the explosion was equivalent to 1.4 billion kilotons of TNT.

Chicxulub. Diameter: 180 km. Age: 65.2 million years. It is believed that this is a crater from the meteorite that killed the dinosaurs.

Parrot. Diameter: 100 km. Age: 35 million years. The crater is literally strewn with diamonds that resulted from the impact.

Khabarovsk. Diameter: 100 km. In 1996, a meteorite weighing 300 g was found. It is believed that this is part of a large iron meteorite, most of which is buried under sediments of the Amur and Ussuri.

Gawler. Diameter: 90 km. Age: 590 million years. The diameter of the meteorite is about 4 km.

Karsky. Diameter: 62 km. Age: 70 million years. The “Kara explosion” is also considered one of the possible culprits in the death of ancient animals.

Barringer. Diameter: 1186 m. Age: 50 thousand years. Preserved better than all the others. In the 1960s, astronauts trained here before flying to the Moon.

Another “contender” is Gulf of Mexico. There is a speculative version that this is a giant crater with a diameter of 2500 km.

Popular geochemistry

How to distinguish an impact crater from other relief features?

“The most important sign of meteorite origin is that the crater is superimposed on the geological terrain randomly,

Explains the head of the laboratory of meteoritics at the Institute of Geochemistry and Analytical Chemistry named after. V.I. Vernadsky (GEOKHI) RAS Mikhail Nazarov.

The volcanic origin of the crater must correspond to certain geological structures, and if they are not there, but the crater is there, this is a serious reason to consider the option of an impact origin.”

Another confirmation of meteorite origin may be the presence of meteorite fragments (impactors) in the crater. This feature works for small craters (hundreds of meters - kilometers in diameter) formed by impacts of iron-nickel meteorites (small stony meteorites usually crumble when passing through the atmosphere). Impactors that form large (tens of kilometers or more) craters, as a rule, completely evaporate upon impact, so finding their fragments is problematic. But traces nevertheless remain: for example, chemical analysis can detect an increased content of platinum group metals in the rocks at the bottom of the crater. The rocks themselves also change under the influence of high temperatures and the passage of the shock wave of the explosion: minerals melt, enter into chemical reactions, rearrange the crystal lattice - in general, a phenomenon called shock metamorphism occurs. The presence of the resulting rocks - impactites - also serves as evidence of the impact origin of the crater. Typical impactites are diaplect glasses formed at high pressures from quartz and feldspar. There are also exotic things - for example, in the Popigai crater, diamonds were recently discovered that were formed from graphite contained in the rocks at high pressure created by a shock wave.

Another external sign of a meteorite crater is the layers of underlying rocks squeezed out by the explosion (basement shaft) or ejected crushed rocks (fill shaft). Moreover, in the latter case, the order of occurrence of rocks does not correspond to the “natural” one. When large meteorites fall in the center of the crater, due to hydrodynamic processes, a slide or even an annular rise is formed - much the same as on water if someone throws a stone there.

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Basic links :

"Astrobleme" is translated from Greek as "star wound". But these wounds are located not on the stars, but on Earth. This is the name given to impact craters - traces left by falling meteorites.

Wilkes Land crater, Antarctica

In the picture, the position of the astrobleme is shown in red. This huge oval structure, 500 km in diameter, is only believed to be a crater. But if this is true, then the trace was left by the largest meteorite that has ever fallen on our planet. It is impossible to look at it even from space, since it is hidden by the ice of Antarctica. Scientists were able to “probe” it with instruments, but the ice does not allow them to take the soil for analysis and confirm or refute the hypothesis.

Vredefort, South Africa

Unlike the previous one, Vredefort is definitely a meteorite crater. The only way to see it in its entirety is in a satellite image. The diameter of the crater reaches 300 km, and its age is 2 billion (!) years.

Sudbury, Canada

Sudbury is almost Vredefort's twin brother: diameter is 250 km, time of fall is about 2 billion years ago. However, when it comes to such huge periods of time, it becomes difficult to determine the age of the crater, even with an accuracy of +- 200 million years. Scientists claim that volcanoes, earthquakes, glaciations and other disasters erased the crater. Let's take our word for it, there is nothing else left for us.

Chicxulub, Mexico

Chicxulub is much younger than its previous venerable brothers - its age is about 65 million years, and its diameter is “only” 180 km. The crater is somewhat historical - it was formed by the same meteorite that “turned off the heat” on Earth, causing the mass death of dinosaurs. The meteorite was about 10 km in diameter, which was enough for a large-scale catastrophe. Giant clouds of dust, raised into the sky by the impact, obscured the sun and a long-term winter set in on the planet. In many places, the vegetation quickly died, the dinosaurs had nothing to eat and they became extinct.

Manicouagan, Canada

This round structure (also called the “Eye of Quebec”), with a diameter of about 100 km, is the Manicouagan crater. A meteorite fell here about 200 million years ago. Over time, the crater smoothed out, and along the edge there formed an unusually shaped lake called Manicouagan. The very word "Manicouagan" in the language of the Indians who once lived here means " where possible find tree bark"The Canadians built dams with hydroelectric power plants here, and the lake became a reservoir.

Popigai, Russia

So we got to our craters, Popigai is the largest of them. The crater basin is approximately 100 km, and it was formed no less than 35 million years ago. Located in Siberia, in the north of the Krasnoyarsk Territory. The name "Popigai" in the language of the local people means "rocky river" - a river of the same name flows here. Due to the monstrous pressure and temperature during the impact, diamonds and other minerals were formed, which are now found here in the Popigai Basin. There is tundra all around and this place is completely deserted - there are no populated areas for hundreds of kilometers around, it is quite difficult to get here.

Acraman, Australia

Akraman is 600 million years old and its diameter is approximately 85 km. An “iridium anomaly” was discovered in the crater - a high content of the rare and valuable metal iridium. This perfectly confirms the hypothesis that a celestial body fell here - meteorites often contain rare elements: gold, platinum, platinum group metals.

Siljan, Sweden

This lake, which resembles a cat in its outline, is actually a meteorite crater. A meteorite fell here 370 million years ago, but time has almost erased all traces of this event. The diameter of the crater is approximately 52 km. The lake and the town of the same name are popular in Sweden; various holidays are held here.

Rochechouart, France

Rochechouart appeared more than 200 million years ago, its diameter is about 23 km, now the crater is filled with water. Next to it is a small town famous for its 13th-century castle (Rochechouart Castle) and the meteorite museum. Meteorite fragments were used in the construction of many houses in the city.

Arizona Crater, USA

And this is probably the most famous crater in the world - Arizona, also called Barringer Crater. The diameter of the crater is 1200 km, it was formed relatively recently - 50,000 years ago. The second name, Barringer Crater, was given in honor of Daniel Barringer, who was the first to confirm the hypothesis about the extraterrestrial cause of the formation of the pit. Daniel was sure that the iron meteorite did not crumble into millions of fragments upon impact, but was hidden in a crater at a shallow depth. So he began methodically drilling into the crater area in search of a meteorite, investing his entire fortune and spending almost 30 years on it. He died of a heart attack after learning that the meteorite could not be underground - the energy of the impact simply evaporated him.

Kaali, Estonia

Kaali is a small lake at the site of a meteorite fall. The event happened quite recently by historical standards - about 4000 years ago, the diameter of the crater is 110 m. In general, this is not one crater, but a whole group of them, numbering 9 pieces, but Kaali is the largest of them. The craters are located on the island of Saaremaa.

A geological formation located under the Antarctic ice sheet, in the Wilkes Land region, with a diameter of about 500 km. It is believed that this is a giant meteorite crater.

Suggestions that there is a giant impact crater in this place were made back in 1962, but until the GRACE research, sufficient evidence was not found.

In 2006, a group led by Ralph von Frese and Laramie Potts, based on measurements of the Earth’s gravitational field by the GRACE satellites, discovered a mass concentrate with a diameter of about 300 km, around which, according to radar data, there is a large ring structure. This combination is typical for impact craters. The latest research from 2009 also shows that there is an impact crater in this place.

Because the structure lies beneath the Antarctic Ice Sheet, direct observations are not yet possible. There are alternative explanations for the occurrence of the mass concentrate, such as mantle plumes and other types of large-scale volcanic activity. If this formation is indeed an impact crater, then the meteorite that created it was about 6 times larger than the meteorite that created the Chicxulub crater, which is believed to have caused the mass extinction at the Cretaceous-Cenozoic boundary.

There is a hypothesis that this impact event could have caused the Permian-Triassic extinction event about 250 million years ago.

Links

• Big Bang in Antarctica - Killer Crater Found Under Ice, Research News, Pam Frost Gorder, June 1, 2006

1. No giant meteorite crater in Wilkes Land, Antarctica
2. GRACE gravity evidence for an impact basin in Wilkes Land, Antarctica

Earth's impact craters
Diameter > 20 km	Akraman | Amelia Creek | Araguaina | Beaverhead | Boltyshsky | Vredefort | Woodleigh | Gosses Bluff | | Kamensky | Karakul | Karsky | Carswell | Keurusselkä | Clearwater (double crater) | Cogram | Conception Bay | Lappajärvi | Logancha | Manicouagan | Mistatin | Montagnais | Morokweng | Mjolnir | Manson | Obolon depression | Slate Islands | Parrot | Presqu'ville | Puchezh-Katunsky | Reese | Rochechouart | Sudbury | St. Martin | Silyan | Steen River | Strangways | Togyz | Tookoonooka | Houghton | Higbury | Chesapeake | Chicxulub | Charlevoix | Shiva | Shoemaker | Yarrabubba
Diameter < 20 км	Arizonan | Arken | Zhamanshin | Ilyinetsky | Kaali | Logoisky | Lonar | Smerdyache | Sobolev | Suavjärvi | Ternovsky | Shiili | Janisjärvi

Wilkes Land Crater Information About

Back in 2006, a group of researchers led by Professor Ralph von Frese from Ohio University discovered a 480-kilometer crater in Antarctica, which, according to scientists, caused the emergence of Australia. A huge and very dense mass of metal was discovered in this crater. The width of the object is approximately 300 kilometers. The depth at which it is located is 848 meters.

The footprint of the giant meteorite could not have been found earlier because it is located in the eastern part of the Antarctic ice sheet at a depth of almost two kilometers. The giant crater is located in the Wilkes Land region in eastern Antarctica and southern Australia. This indicates that the object that left this crater could have caused the break-off of Australia from the supercontinent Gondwana.

The discovery was made through analysis of gravitational deflection data recorded by NASA's GRACE satellites. They recorded a 320-kilometer gravity anomaly.

Experts estimate that the crater is about 250 million years old. Thus, it turns out that it arose much earlier than the Chicxulub crater, the emergence of which is associated with the death of many prehistoric animals.

Estimating the size of the celestial body that left behind the found crater, scientists believe that it had a diameter of about 48 kilometers - four or five times larger than the asteroid that created the Chicxulub crater.

“The impact in the Wilkes Land region is much larger than what destroyed the dinosaurs and probably caused a terrible catastrophe,” Dr. von Frese said at the time.

In addition to the cosmic version of the origin of the crater, which includes assumptions about a large asteroid, other, more intriguing hypotheses have appeared. There are suggestions that under the ice of Antarctica there is a giant alien spaceship.