Keurusselkä
Keurusselkä | |
---|---|
Location | Central Finland |
Coordinates | 62°11′N 24°41′E / 62.183°N 24.683°E |
Basin countries | Finland |
Max. length | 27 km (17 mi) |
Surface area | 117.30 km2 (45.29 sq mi) |
Average depth | 6.4 m (21 ft) |
Max. depth | 40 m (130 ft) |
Surface elevation | 105.4 m (346 ft) |
Settlements | Keuruu, Mänttä |
Keurusselkä is a lake in Central Finland between the towns of Keuruu to the north and Mänttä to the south. It covers an area of 117.3 km2 (45.3 sq mi). Its average depth is 6.4 m (21 ft) with a maximum depth of 40 m (130 ft). The surface lies at 105.4 m (346 ft) above sea level. The lake is 27 km (17 mi) long and is a part of the Kokemäenjoki water system.[1][2][3] Keurusselkä gained international publicity in 2004 when a pair of amateur geologists discovered an ancient impact structure on the western shore of the lake.[4]
Etymology
Keurusselkä was originally only the name of the largest fjard of the lake, while the lake was known as Väärinkeuru or Keuruvesi. The element keuru is a dialectal word meaning "crooked", in this context referring to the shape of the lake. The older names were displaced by the name Keurusselkä in the 19th century. The name of Keuruu is derived from the lake's name.[5]
Environmental issues
In 1986, the Keurusselkä region was heavily contaminated (70
Apart from radioactivity, the water quality is also weakened by
Keurusselkä impact structure
Keurusselkä covers an ancient impact crater remnant,[7] which was discovered in 2003 by amateur geologists.[4] Shatter cones, horsetail-shaped formations in rocks specifically formed in meteor impacts, have been found in an 11.5 km (7.1 mi) wide area, but it is possible that the area containing shatter cones may be only the central uplift of the crater. Weak traces based on digital elevation data suggest possible ring structures from 10 km (6.2 mi) to as wide as about 30 km (19 mi) in diameter. This would make Keurusselkä the largest impact structure in Finland surpassing the Lappajärvi crater.[3] In addition to the shatter cones, microscopic studies of samples from a breccia boulder have revealed shock metamorphic features, (planar fractures and planar deformation features) in quartz grains, which formed when the rock underwent extreme shock pressures of between 7–35 GPa (1,000,000–5,100,000 psi).[4]
Sparse gravity data shows a negative anomaly (an area of lower
Airborne
Only some 30 km (19 mi) east from the centre of the Keurusselkä impact structure is Karikkoselkä, a much smaller and younger impact crater.
See also
- Impact craters in Finland
References
- ^ "Finnish lakes larger than 40 square kilometers". www.environment.fi. Finnish Environmental Institute. 2010. Archived from the original on 2011-05-22. Retrieved 2011-05-07.
- ^ a b c d Ilus H, Klemola S, Vartti VP, Mattila J, Ikäheimonen TK (2005). "137Cs in aquatic organisms in the southern Lake Keurusselkä (Finland)" (PDF). Archived from the original (PDF) on 2011-07-21. Retrieved 2011-05-07.
- ^ a b c d e Pesonen L, Hietala S, Poutanen M, Moilanen J, Lehtinen M, Ruotsalainen H (2005). "The Keurusselkä Meteorite Impact Structure, Central Finland: Geophysical Data" (PDF). Retrieved 2011-05-07.
- ^ a b c Hietala S, Moilanen J (2004). "Keurusselkä - A New Impact Structure in Central Finland" (PDF). Lunar and Planetary Science XXXV: 1619. Retrieved 2011-05-07.
- ^ "SuomalainenPaikannimikirja_e-kirja_kuvallinen.pdf" (PDF). kaino.kotus.fi (in Finnish). p. 157. Retrieved April 17, 2023.
- ^ "Fishing ground of Keuruu". Kalapaikka.net. Archived from the original on 2007-10-08. Retrieved 2006-05-08.
- ^ "Keurusselkä". Earth Impact Database. Planetary and Space Science Centre University of New Brunswick Fredericton. Retrieved 2009-08-17.
- ^ M. Schmieder; F. Jourdan; S. Hietala; J. Moilanen; T. Öhman; E. Buchner (2009). "A HIGH-PRECISION LATE MESOPROTEROZOIC 40Ar/39Ar AGE FOR THE KEURUSSELKÄ IMPACT STRUCTURE (FINLAND)" (PDF). 40th Lunar and Planetary Science Conference: 1028. Archived from the original (PDF) on 2012-10-12. Retrieved 2011-05-07.
External links
- University of Helsinki, Division of Geophysics. "Integrated Study of Keurusselkä Impact Structure". Project home page. Archived from the original on 2011-07-20.
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