Impact structures in Finland

As of June 2018, 12 confirmed impact structures have been found in Finland. They are listed below, sorted by original diameter.

List of identified impact structures in Finland
Structure name Crater type Diameter (km) Depth (m) Age (Myr) Geologic period (epoch) Location Municipality Impact origin shown [Note 3] Notes
Original (estimate)

[Note 1]

Current Original (estimate)

[Note 1]

Current (buried structure) Current (solid surface)

[Note 2]

Min Max Best fit
Keurusselkä Complex 30[1] 14[2] 820[3] N/A 1141[4] 1161[4] 1150[4] Stenian 62°07′49″N 24°37′58″E / 62.1302°N 24.6327°E / 62.1302; 24.6327 Keuruu / Mänttä-Vilppula 2004[5]

2010[6]

Heavily eroded, only remnants of central peak remain.
Lappajärvi Complex[7] 20[7] 17[7] 730[3] 137[8] 77.07[9] 78.63[9] 77.85[9] Cretaceous (Late) 63°08′40″N 23°39′03″E / 63.1444°N 23.6508°E / 63.1444; 23.6508 Lappajärvi / Alajärvi / Vimpeli 1968[10]

1970[11]

1976 [12]

Preserved well, rim outside lake largely intact.
Paasselkä Complex?[7] 10[7] 590[3] 74[13] 229.2

[14][15]

232.8

[14][15]

231.0

[14][15]

Triassic (Late) 62°09′18″N 29°24′03″E / 62.1549°N 29.4008°E / 62.1549; 29.4008 Savonlinna / Kitee 1999[16]

2003

2008[17]

Bay of Orivesi lake in Greater Saimaa.
Lumparn Complex[7] 9[7] 9[7] - 10[18] 570[3] 450[19] 1250[19] 580[19] Ectasian to Ordovician 60°08′34″N 20°07′17″E / 60.1429°N 20.1215°E / 60.1429; 20.1215 Jomala / Lemland / Lumparland / Sund 1993[18]

1997

Bay of the Archipelago sea.
Söderfjärden Complex,[7] polygonal (hexagonal) 6.6[7] 6.6[7] 520[3] 55[8] 520[7] - 640[20] Cambrian (Early) 63°00′14″N 21°33′28″E / 63.0039°N 21.5579°E / 63.0039; 21.5579 Vaasa / Korsholm / Malax 1978

1985

2013[21]

Extremely well preserved; rim nearly entirely intact, buried soon after impact, later exhumed. Dried bay of Kvarken.
Sääksjärvi Simple?[7] 5[7] 4.5[7] - 5[22] 480[3] 9.1[23] 544[22] 576[22] 560[22] Ediacaran 61°24′24″N 22°22′45″E / 61.4066°N 22.3792°E / 61.4066; 22.3792 Kokemäki 1969[24]

1980

1997

Central part of the Sääksjärvi lake.
Suvasvesi N Complex?[7] 4[7][25] 450[3] 79.7[26] 88.1[26] 85[26] Cretaceous (Late) 62°39′11″N 28°10′43″E / 62.6530°N 28.1786°E / 62.6530; 28.1786 Kuopio / Leppävirta 1995

1996[25]

Kukkarinselkä; open water in the Suvasvesi lake.
Suvasvesi S Simple?

Complex?

~4 450[3] 679[26] 727[26] 710[26] Cryogenian, possibly but unlikely Tonian 62°35′33″N 28°12′51″E / 62.5924°N 28.2143°E / 62.5924; 28.2143 Kuopio / Leppävirta 2001[27]

2002[28] 2003

Haapaselkä; open water in the Suvasvesi lake.
Iso-Naakkima Simple[7] < 4[7] 2[7] - 3[29] 450[3] - 600[29] 160[29] N/A 900[30] 1200[30] Stenian or Tonian 62°12′08″N 27°07′31″E / 62.2023°N 27.1252°E / 62.2023; 27.1252 Pieksämäki / Mikkeli 1993[29] Buried, only partly under the Iso-Naakkima lake
Saarijärvi Simple?[7] 3.4[7] 1.5[7][31] - 2[32] 420[3] 0[21] 541[21] Cambrian to Quaternary 65°17′29″N 28°23′22″E / 65.2915°N 28.3894°E / 65.2915; 28.3894 Taivalkoski 1997[33]

1998[31]

2013[21]

Central part of the Saarijärvi lake.
Summanen Simple? 2.6[34] 640[3] 200[34] 41[35] 2.588[34][36] 1910[36] Orosirian to Neogene 62°38′52″N 25°22′42″E / 62.6479°N 25.3782°E / 62.6479; 25.3782 Saarijärvi 2007[37]

2018[34]

Central part of the Summanen lake.
Karikkoselkä Simple[7] 3[7] 1.3[7] 640[3] 26[38] 230[39] 260[39] - 458[40] (Late) Ordovician to (Early) Triassic 62°13′16″N 25°14′45″E / 62.2212°N 25.2459°E / 62.2212; 25.2459 Petäjävesi 1996[38]

1999[39]

2000

Open water in Petäjävesi lake

Note 1: The "original" crater dimensions are coarse estimates. Original depths were calculated using the given original diameter using the Impact: Earth! program.

Note 2: "Current solid surface" topography is calculated from the deepest floor (regardless whether it is underwater or on dry land) to highest rim crest; other depth values give the depth of the floor in relation to the original terrain, thus excluding the rim and/or central uplift.

Note 3: Evidence for impact origin for a given structure is often provided in several publications. The year column includes some publications where some evidence of impact origin was provided even though an impact was not necessarily suggested by the authors; somewhere an impact was suggested even though the proof wasn't conclusive; and somewhere definite proof was provided.

General note 1: Crater sizes and shapes vary according to local differences. For example, depending on where you measure the crater diameter the result may vary (craters are seldom perfect circles). This is affected by, e.g., impact angle (low < 5-10 degree impact angles cause more elliptical craters) and local zones of weakness (may cause the crater to become polygonal).

General note 2: On Earth the (theoretical) transition diameter between simple and complex craters is 2 – 4 km. Such small craters may be either end member or some intermediate form, and thus the given dimension estimates may be off. The depth may be off by ~50 %.

References

  1. ^ Pesonen, L. J.; Hietala, S.; Poutanen, M.; Moilanen, J.; Lehtinen, M.; Ruotsalainen, H. E. (2005). "The Keurusselkä meteorite impact structure, central Finland: Geophysical data" (PDF). XXII Geophysics Days: 165–169.
  2. ^ Hietala, Satu; Moilainen, Jarmo (March 2007). "Keurusselkä - distribution of shatter cones" (PDF). Lunar and Planetary Science. XXXVIII (1338): 1762. Bibcode:2007LPI....38.1762H.
  3. ^ a b c d e f g h i j k l Collins, Gareth; Melosh, H. Jay; Robert Marcus. "Impact: Earth!". Imperial College London.
  4. ^ a b c Schmieder, Martin; Jourdan, Fred; Moilanen, Jarmo; Buchner, Elmar; Öhman, Teemu (2016-02-08). "A Late Mesoproterozoic40Ar/39Ar age for a melt breccia from the Keurusselkä impact structure, Finland". Meteoritics & Planetary Science. 51 (2): 303–322. Bibcode:2016M&PS...51..303S. doi:10.1111/maps.12594. ISSN 1086-9379.
  5. ^ Hietala, Satu; Moilanen, Jarmo (March 2004). "Keurusselkä - a new impact structure in central Finland" (PDF). Lunar and Planetary Science. XXXV: 1619.
  6. ^ FERRIÈRE, Ludovic; RAISKILA, Selen; OSINSKI, Gordon R.; PESONEN, Lauri J.; LEHTINEN, Martti (2010-06-10). "The Keurusselkä impact structure, Finland-Impact origin confirmed by characterization of planar deformation features in quartz grains". Meteoritics & Planetary Science. 45 (3): 434–446. Bibcode:2010M&PS...45..434F. doi:10.1111/j.1945-5100.2010.01032.x. ISSN 1086-9379.
  7. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z Abels, Andreas; Plado, Jüri; Pesonen, Lauri J.; Lehtinen, Martti (2002), "The Impact Cratering Record of Fennoscandia — A Close Look at the Database", Impacts in Precambrian Shields, Springer Berlin Heidelberg, pp. 1–58, doi:10.1007/978-3-662-05010-1_1, ISBN 9783642078033
  8. ^ a b "Karttapaikka". asiointi.maanmittauslaitos.fi (in Finnish). Maanmittauslaitos. Retrieved 2018-06-29.
  9. ^ a b c Kenny, G.G.; Schmieder, M.; Whitehouse, M.J.; Nemchin, A.A.; Morales, L.F.G.; Buchner, E.; Bellucci, J.J.; Snape, J.F. (2019). "A new U-Pb age for shock-recrystallised zircon from the Lappajärvi impact crater, Finland, and implications for the accurate dating of impact events". Geochimica et Cosmochimica Acta. 245: 479–494. Bibcode:2019GeCoA.245..479K. doi:10.1016/j.gca.2018.11.021. S2CID 133730451.
  10. ^ Svensson, Nils-Bertil (1968-02-03). "Lake Lappajärvi, Central Finland: a Possible Meteorite Impact Structure". Nature. 217 (5127): 438. Bibcode:1968Natur.217Q.438S. doi:10.1038/217438a0. S2CID 4202217.
  11. ^ Lehtinen, Martti (1970). "New evidence for an impact origin of Lake Lappajärvi, western Finland: a preliminary report". Bulletin of the Geological Society of Finland. 42: 89–93. doi:10.17741/bgsf/42.008.
  12. ^ Lehtinen, Martti (1976). Lake Lappajärvi, a meteorite impact site in western Finland (PDF). ISBN 978-951-690-041-7.
  13. ^ "Orivesi (Saimaa) (04.311.1.001)". Lake & Sea Wiki. Finnish Environment Institute (SYKE).
  14. ^ a b c SCHMIEDER, Martin; SCHWARZ, Winfried H.; BUCHNER, Elmar; TRIELOFF, Mario; MOILANEN, Jarmo; ÖHMAN, Teemu (April 2010). "A Middle-Late Triassic 40Ar/39Ar age for the Paasselkä impact structure (SE Finland)". Meteoritics & Planetary Science. 45 (4): 572–582. Bibcode:2010M&PS...45..572S. doi:10.1111/j.1945-5100.2010.01041.x. ISSN 1086-9379.
  15. ^ a b c Schwarz, Winfried H.; Schmieder, Martin; Buchner, Elmar; Trieloff, Mario; Moilanen, Jarmo; Öhman, Teemu (2014-12-18). "A Carnian40Ar/39Ar age for the Paasselkä impact structure (SE Finland)-An update". Meteoritics & Planetary Science. 50 (1): 135–140. doi:10.1111/maps.12407. ISSN 1086-9379.
  16. ^ Pesonen, L. J.; Kuivasaari, T.; Lehtinen, M.; Elo, S. (1999). "Paasselkä - a new meteorite impact structure in Eastern Finland" (PDF). 62nd Annual Meteoritical Society Meeting: 5039.
  17. ^ SCHMIEDER, Martin; MOILANEN, Jarmo; BUCHNER, Elmar (July 2008). "Impact melt rocks from the Paasselkä impact structure (SE Finland): Petrography and geochemistry". Meteoritics & Planetary Science. 43 (7): 1189–1200. Bibcode:2008M&PS...43.1189S. doi:10.1111/j.1945-5100.2008.tb01122.x. ISSN 1086-9379.
  18. ^ a b Svensson, N.-B. (1993). "Lumparn Bay: A Meteorite Impact Crater in the Aland Archipelago, Southwest Finland". Meteoritics. 28 (3): 445. Bibcode:1993Metic..28S.445S.
  19. ^ a b c Abels, A.; Mannola, P.; Lehtinen, M.; Bergman, L.; Pesonen, L. J. (1998). "New Observations of the Properties of the Lumparn Impact Structure, Aland Islands, Southwestern Finland". Meteoritics & Planetary Science. 33: A7 – A8. Bibcode:1998M&PSA..33Q...7A. doi:10.1111/j.1945-5100.1998.tb01327.x.
  20. ^ Schmieder, M; Jourdan, F.; Öhman, T.; Tohver, E.; Mayers, C.; Frew, A. (March 2014). "A Proterozoic 40Ar/39Ar Age for the Söderfjärden Impact Structure, Finland". Lunar and Planetary Science. 45 (1777): 1301. Bibcode:2014LPI....45.1301S.
  21. ^ a b c d Öhman, Teemu; Preeden, Ulla (2013-04-10). "Shock metamorphic features in quartz grains from the Saarijärvi and Söderfjärden impact structures, Finland". Meteoritics & Planetary Science. 48 (6): 955–975. Bibcode:2013M&PS...48..955O. doi:10.1111/maps.12112. ISSN 1086-9379.
  22. ^ a b c d Müller, Norbert; Hartung, Jack B.; Jessberger, Elmar K.; Reimold, Wolf U. (March 1990). "40Ar-39Ar ages of Dellen, Jänisjärvi, and Sääksjärvi impact craters". Meteoritics. 25 (1): 1–10. Bibcode:1990Metic..25....1M. doi:10.1111/j.1945-5100.1990.tb00964.x. ISSN 0026-1114.
  23. ^ "Sääksjärvi (35.152.1.001)". Lake & Sea Wiki. Finnish Environment Institute (SYKE).
  24. ^ Papunen, Heikki (1969). "Possible impact metamorphic textures in the erratics of the Lake Sääksjärvi area in Southwestern Finland" (PDF). Bulletin of the Geological Society of Finland. 41: 151–155. doi:10.17741/bgsf/41.016. Archived from the original (PDF) on 2018-06-02. Retrieved 2018-06-29.
  25. ^ a b Pesonen, L. J.; Lehtinen, M.; Deutsch, A.; Elo, S.; Lukkarinen, H. (March 1996). "New Geophysical and Petrographic Results of the Suvasvesi N Impact Structure, Finland" (PDF). Lunar and Planetary Science. XXVII: 1511. Bibcode:1996LPI....27.1021P.
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  27. ^ Werner, S.C.; Plado, Jüri; Pesonen, L. J.; Kuulusa, M. (10 September 2001). "The two Suvasvesi lakes in Central Finland - A possible doublet impact structure". Meteoritics & Planetary Science. 36 (9): A223 – A224. Bibcode:2001M&PSA..36Q.223W.
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