List of possible impact structures on Earth


This is a list of possible impact structures on Earth. More than 130 features on Earth include candidate impact sites that have appeared several times in the literature and/or have been endorsed by the Impact Field Studies Group and/or Expert Database on Earth Impact Structures,. The Earth Impact Database is used at Wikipedia as authoritative using the terminology "confirmed". The list below includes a three-step confidence level as indicated by the Russian Academy of Sciences, by Anna Mikheeva: 1 for probable, 2 for potential, 3 for questionable. Level 4 is given to discredited structures, hence represent geological features other than impact craters. Structures with confidence 0 are considered "confirmed" or "proven" and should be placed in the lists per continent.

List of possible impact structures

The following tables list geological features on Earth that some individuals have associated with impact events, but for which there is currently no confirming scientific evidence in the peer-reviewed literature. In order for a structure to be a confirmed as an impact crater, it must meet a stringent set of well established criteria. Some proposed impact structures are eventually confirmed, whereas others are shown to be misidentified. Recent extensive surveys have been done for Australian, African, and South American craters, as well as those in the Arab world. A book review by A. Crósta and U. Reimold disputes some of the evidence presented for several of the South American structures.
Confidence0 - proven
Confidence1 – probable
Confidence2 – potential
Confidence3 – questionable
Confidence4 – discredited
DiameterKilometers
AgeApproximate

NameLocationConfidenceDiameter Age NotesImageCoordinates
38th Parallel structuresUnited States variable
Ak-Bura Tajikistan10.080
Al MadafiSaudi Arabia16
Alamo bolide impactUnited States 0367
AnéfisMali23.9
Aorounga CentralChad011.6
ArganatyKazakhstan 0300250
ArlitNiger210?
Australian impact structureAustralia Highly speculative600
AzuaraSpain1
Bajada del DiabloArgentina240
Bajo HondoArgentina 23.9
Bangui magnetic anomalyCentral African Republic2
Bateke PlateauGabon37.1
BedoutAustralia 2250250
Bee BluffUnited States 02.4
BjörköSweden 1101200
Bloody CreekCanada 140?
Bohemian craterCzech Republic2
Bow CityCanada 2870
Bowers craterAntarctic Ocean 2100
Brushy Creek FeatureUnited States 12.0
BurckleIndian Ocean1
Catalina structures
Pacific Ocean 2
Cerro do JarauBrazil 110117
Charity ShoalCanada 21.2
CorossolCanada 34
Darwin CraterTasmania01.20.816
DecorahUnited States 25.6470
Diamantina River ring featureAustralia 2120300
Dumas magnetic anomalyCanada 13.2
DuolunChina 2
El-BazEgypt14?
EltaninPacific Ocean 02.5
Faya BasinChad12
Falkland Plateau anomalyAtlantic Ocean
2250
Fried Egg structureAtlantic Ocean 2617
Garet El LefetLibya13?
Gatun structurePanama1320
General San MartínArgentina2111.2
GnargooAustralia 175
GuardaPortugal130200
Gulf of MexicoUnited States, Mexico, Cuba
Hartney anomalyCanada 18
HiawathaGreenland231
HickmanAustralia 230
HicoUnited States 19
HotchkissCanada 14
HowellUnited States 12.5
Ibn-BatutahLibya22.5
IshimKazakhstan 0300
IturraldeBolivia18.0
Jackpine Creek magnetic anomalyCanada 125
Jebel HadidLibya24.7
Jeptha KnobUnited States 04.3425
JohnsonvilleUnited States 011
Jwaneng SouthBotswana21.3
LunaIndia22.1
KebiraEgypt231100
KilmichaelUnited States 11345
Krk structureCroatia21240
Kurai BasinRussia 120
La DulceArgentina12.8
LabynkyrRussia067
Lac IroChad113?
Lairg Gravity LowScotland2401200
Lake ChekoRussia 350
Lake Tai China 1
Loch LevenScotland2290
Lorne BasinAustralia 230
Lycksele structure 2Sweden2130
Madagascar structure 3Madagascar412?
Magyarmecske anomalyHungary17299
MahuikaNew Zealand 2
Maniitsoq structureGreenland21003000
Mejaouda Mauritania13
MerewetherCanada 020
Meseta de la Barda NegraArgentina41.5
Middle-Urals Ring StructureRussia1
Mistassini-Otish impact structureCanada 16002200
Mount Ashmore domeIndian Ocean 235
MoussoChad23.8
Mt. OikeyamaJapan290
MulkarraAustralia 117105
Nastapoka arcCanada 3450
Ouro NdiaMali23
PantasmaNicaragua310?
Panther MountainUnited States 110375
Peerless structureUnited States 16
PiratiningaBrazil 312117
Praia GrandeBrazil 12084
RamgarhIndia 03?
RossAntarctic Ocean 2
Rubielos de la CéridaSpain0
SakhalinkaPacific Ocean 21270
São Miguel do TapuioBrazil 122120
ShanghewanChina 130?
ShivaIndian Ocean150066
ShiyliKazakhstan05.5
SilverpitAtlantic Ocean 120
SirenteItaly410
Sithylemenkat LakeUnited States 312
Smerdyacheye LakeRussia120
Sudan 3 Sudan2.8?
Sudan 2 Sudan210?
Sudan 1 Sudan26?
Svetloyar LakeRussia040
TakamatsuJapan115
Tarek Egypt32.1
Tatarsky NorthPacific Ocean 214?
Tatarsky SouthPacific Ocean 220?
Tefé River structureBrazil 215
TalundillyAustralia 184
TemimichatMauritania10.7
TsenkherMongolia13.65
Toms CanyonUnited States 12235
Umm al BinniIraq03.4
Ust-KaraRussia 225
VélingaraSenegal148
VersaillesUnited States 11.5
VichadaColombia 250
Victoria IslandUnited States 25.5
Warburton EastAustralia 2200
Warburton WestAustralia 200
WeaubleauUnited States 119
Wembo-Nyama DR Congo2
Wilkes Land 2Antarctica2480
WoodburyUnited States 17
YallalieAustralia 012
Zerelia WestGreece220
Zerelia EastGreece210

Overview

The Cheko crater is thought by one research group to be the result of the famous Tunguska event, although sediments in the lake have been dated back more than 5,000 years. There is highly speculative conjecture about the supposed Sirente impact causing the Roman emperor Constantine's vision at Milvian Bridge.
The Burckle crater and Umm al Binni structure are proposed to be behind the floods that affected Sumerian civilization. The Kachchh impact may have been witnessed by the Harappan civilization and mentioned as a fireball in Sanskrit texts.
The ages of the Bloody Creek crater and Hiawatha crater are uncertain.
As the trend in the Earth Impact Database for about 26 confirmed craters younger than a million years old show that almost all are less than in diameter, the suggestion that two large craters, Mahuika and Burckle, formed just within the last few millennia has been met with skepticism.
However, the source of the young and enormous Australasian strewnfield is suggested to be a crater about across somewhere in Indochina, with Hartung and Koeberl proposing the elongated Tonlé Sap lake in Cambodia as a suspect structure.
The Decorah crater has been conjectured as being part of the Ordovician meteor event.
Several twin impacts have been proposed such as the Rubielos de la Cérida and Azuara, Cerro Jarau and Piratininga, and Warburton East and West. However, adjacent craters may not necessarily have formed at the same time such as case of the confirmed Clearwater East and West lakes.
Some confirmed impacts like Sudbury or Chicxulub are also sources of magnetic anomalies and/or gravity anomalies. The magnetic anomalies Bangui and Jackpine Creek, the gravity anomalies Wilkes Land crater and Falkland Islands, and others have been considered as being of impact origin. Bangui apparently has been discredited, but appears again in a 2014 table of unconfirmed structures in Africa by Reimold and Koeberl.
Several anomalies in Williston Basin were identified by Swatzky in the 1970s as astroblemes including Viewfield, Red Wing Creek, Eagle Butte, Dumas, and Hartney, of which only the last two are unconfirmed.
The Eltanin impact has been confirmed but, as it fell into the Pacific Ocean, apparently no crater was formed. The age of Silverpit and the confirmed Boltysh crater, as well as their latitude, has led to the speculative hypothesis that there may have been several impacts during the KT boundary. Of the five oceans in descending order by area, namely the Pacific, Atlantic, Indian, Antarctic, and Arctic, only the smallest does not yet have a proposed unconfirmed impact crater.
Craters larger than in the Phanerozoic are notable for their size as well as for the possible coeval events associated with them especially the major extinction events.
For example, the Ishim impact structure is conjectured to be bounded by the late Ordivician-early Silurian, the two Warburton basins have been linked to the Late Devonian extinction, both Bedout and the Wilkes Land crater have been associated with the severe Permian–Triassic extinction event, Manicouagan was once thought to be connected to the Triassic–Jurassic extinction event but more recent dating has made it unlikely, while the consensus is the Chicxulub impact caused the one for Cretaceous–Paleogene.
However, other extinction theories employ coeval periods of massive volcanism such as the Siberian Traps and Deccan Traps.

Undiscovered but inferred

There is geological evidence for impact events having taken place on Earth on certain specific occasions, which should have formed craters, but for which no impact craters have been found. In some cases this is because of erosion and Earth's crust having been recycled through plate tectonics, in others likely because exploration of the Earth's surface is incomplete. Typically the ages are already known and the diameters can be estimated.
Parent crater ofExpected crater diameterAgeNotes
Dakhleh glass0.4 km150 ka
Argentinian tektites5 km480 ka
Australasian tektites32–114 km780 ka
Central American tektites14 km820 ka
Skye ejecta depositsUnknown60 Ma
Stac Fada Member40 km1.2 Ga
Barberton Greenstone Belt microtektites500 km3.2 Ga
Marble Bar impact spherules"hundreds of kilometers"3.4 Ga

Mistaken identity

Some geological processes can result in circular or near-circular features that may be mistaken for impact craters. Some examples are calderas, maars, sinkholes, glacial cirques, igneous intrusions, ring dikes, salt domes, geologic domes, ventifacts, tuff rings, forest rings, and others. Conversely, an impact crater may originally be thought as one of these geological features, like Meteor Crater or Upheaval Dome.
The presence of shock metamorphism and shatter cones are important criteria in favor of an impact interpretation, though massive landslides may produce shock-like fused rocks called "frictionite".