Ilumetsa crater

{{Short description|Impact craters in Estonia}}

{{Infobox terrestrial impact site

| name = Ilumetsa crater

| other_name =

| photo = Ilumetsa crater, Estonia.jpg

| photo_caption = Ilumetsa crater

| map = Estonia

| map_caption = Asteroid impact location in Estonia

| coordinates = {{coord|57|57|36.17|N|27|24|10.43|E|region:EE-39_type:landmark_scale:50000|display=inline}}

| confidence = Probable

| diameter = {{cvt| 80|m|||}}

| depth =

| age = 7 ka

| exposed =Yes

| drilled =Yes

| imp_size =

| bolide =

| country = Estonia

| state =

}}

Ilumetsa is a set of two probable meteorite craters{{Cite journal |last1=Osinski |first1=Gordon R. |last2=Grieve |first2=Richard A. F. |last3=Ferrière |first3=Ludovic |last4=Losiak |first4=Ania |last5=Pickersgill |first5=Annemarie |last6=Cavosie |first6=Aaron J. |last7=Hibbard |first7=Shannon M. |last8=Hill |first8=Patrick |last9=Bermudez |first9=Juan Jaimes |last10=Marion |first10=Cassandra L. |last11=Newman |first11=Jennifer D. |date=2022-07-21 |title=Impact Earth: A review of the terrestrial impact record |journal=Earth-Science Reviews |volume=232 |language=en |pages=104112 |doi=10.1016/j.earscirev.2022.104112 |bibcode=2022ESRv..23204112O |s2cid=250965097 |issn=0012-8252|doi-access=free }} in Estonia. {{ambiguous|date=December 2013}}

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.{{Cite journal |last=Plado |first=Jüri |date=October 2012 |title=Meteorite impact craters and possibly impact-related structures in Estonia: Meteorite impact record of Estonia |journal=Meteoritics & Planetary Science |language=en |volume=47 |issue=10 |pages=1590–1605 |doi=10.1111/j.1945-5100.2012.01422.x|s2cid=129740410 |doi-access=free }} 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 radiocarbon dating the gyttja and peat from the very bottom of the crater shaped depression.{{Cite journal |last=Liiva A., Kessel H., and Aaloe A. |date=1979 |title=Age of the Ilumetsa craters. (in Estonian). |journal=Eesti Loodus |volume=12 |pages=762–764}} The lowermost organic beds were dated to 6030 +/-100 14C years (7170– 6660 cal. years BP). Recent radiocarbon 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.{{Cite journal |last1=Losiak |first1=A. |last2=Jõeleht |first2=A. |last3=Plado |first3=J. |last4=Szyszka |first4=M. |last5=Kirsimäe |first5=K. |last6=Wild |first6=E. M. |last7=Steier |first7=P. |last8=Belcher |first8=C. M. |last9=Jazwa |first9=A. M. |last10=Helde |first10=R. |date=February 2020 |title=Determining the age and possibility for an extraterrestrial impact formation mechanism of the Ilumetsa structures (Estonia) |journal=Meteoritics & Planetary Science |language=en |volume=55 |issue=2 |pages=274–293 |doi=10.1111/maps.13431 |bibcode=2020M&PS...55..274L |s2cid=213799334 |issn=1086-9379|doi-access=free }}

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;,{{Cite journal |last=Aaloe A. |date=1963 |title=New data on the structure of Ilumetsa craters. (in Russian). |journal=Eesti NSV Teaduste Akadeemia Geoloogia Instituudi Uurimused |issue=11 |pages=35–43}} 2) only a small thickness of glacial sediments, 3) simultaneous formation of both structures as showed by radiocarbon dating.