Ilumetsa crater

Ilumetsa is a set of two probable meteorite craters[1] in Estonia.

Ilumetsa crater
Ilumetsa crater
Impact crater/structure
ConfidenceProbable
Diameter80 m (260 ft)
Age7 ka
ExposedYes
DrilledYes
Location
Coordinates57°57′36.17″N 27°24′10.43″E
CountryEstonia
Ilumetsa crater is located in Europe
Ilumetsa crater
Ilumetsa crater
Asteroid impact location in Europe

The Ilumetsa site is located in south eastern Estonia and it consists of two structures, located 725 m from each other. Their diameters are: 75–80 m and ~50 m. Their true depths are about 8 and 3.5 m, respectively.[2] Both structures are surrounded by a rim up to a few meters high: the rims are highest in their eastern parts with maximum rim heights of Ilumetsa Large 4.5 m and 1.5 m for Ilumetsa Small.

The Large Ilumetsa structure has been dated by measuring 14C gyttja and peat from the very bottom of the crater shaped depression.[3] The lowermost organic beds were dated to 6030 +/-100 14C years (7170– 6660 cal. years BP). Recent 14C dating charcoals buried within assumed proximal ejecta blankets of these crater-like features showed Ilumetsa Large and Ilumetsa Small formed simultaneously between 7170 and 7000 cal. years BP.[4]

No clear meteorite fragments or shock metamorphic effects were ever found around those structures. Because of that Ilumetsa is not a proven impact crater. However, indirect lines of evidence are enough to call it a "probable" impact site. It is: 1) presence of deformed sedimentary beds (including the rim consisting of sands mixed with numerous clayey till lenses;[5], 2) only a small thickness of glacial sediments,[2] 3) simultenous formation of both structures as showed by 14C dating.[4]

References
  1. Osinski, Gordon R.; Grieve, Richard A. F.; Ferrière, Ludovic; Losiak, Ania; Pickersgill, Annemarie; Cavosie, Aaron J.; Hibbard, Shannon M.; Hill, Patrick; Bermudez, Juan Jaimes; Marion, Cassandra L.; Newman, Jennifer D. (2022-07-21). "Impact Earth: A review of the terrestrial impact record". Earth-Science Reviews. 232: 104112. Bibcode:2022ESRv..23204112O. doi:10.1016/j.earscirev.2022.104112. ISSN 0012-8252. S2CID 250965097.
  2. Plado, Jüri (October 2012). "Meteorite impact craters and possibly impact-related structures in Estonia: Meteorite impact record of Estonia". Meteoritics & Planetary Science. 47 (10): 1590–1605. doi:10.1111/j.1945-5100.2012.01422.x. S2CID 129740410.
  3. Liiva A., Kessel H., and Aaloe A. (1979). "Age of the Ilumetsa craters. (in Estonian)". Eesti Loodus. 12: 762–764.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. Losiak, A.; Jõeleht, A.; Plado, J.; Szyszka, M.; Kirsimäe, K.; Wild, E. M.; Steier, P.; Belcher, C. M.; Jazwa, A. M.; Helde, R. (February 2020). "Determining the age and possibility for an extraterrestrial impact formation mechanism of the Ilumetsa structures (Estonia)". Meteoritics & Planetary Science. 55 (2): 274–293. Bibcode:2020M&PS...55..274L. doi:10.1111/maps.13431. ISSN 1086-9379. S2CID 213799334.
  5. Aaloe A. (1963). "New data on the structure of Ilumetsa craters. (in Russian)". Eesti NSV Teaduste Akadeemia Geoloogia Instituudi Uurimused (11): 35–43.


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