Siljan Ring
Siljan Ring | |
---|---|
Lake Siljan takes up a large part of the southwestern edge of the now much-eroded crater. | |
Impact crater/structure | |
Confidence | Confirmed |
Diameter | 52 km (32 mi) |
Age | 376.8 ± 1.7 Ma Frasnian |
Exposed | Yes |
Drilled | Yes |
Location | |
Coordinates | 61°02′N 14°55′E / 61.04°N 14.92°E |
Country | Sweden |
District | Dalarna |
The Siljan Ring (
The area around the Siljan Ring has been the site of recent prospecting for oil and natural gas, though none of the projects has so far been commercially viable. There are large deposits of lead and zinc near Boda at the eastern edge of the Ring.
There are several lakes in the vicinity, the largest of which is Siljan on the south-southwestern edge of the crater, with the smaller Orsa Lake to the west and Skattungen and Ore on the northeastern margin.
Geology
The Siljan Ring consists of an annular outcrop of Lower Paleozoic sedimentary rocks within Proterozoic granites of the Dala series.[8]
Basement rocks
In Dalarna, the basement rocks consist of granites dated as 1.6 billion years old, putting them at the boundary between the Paleoproterozoic and the Mesoproterozoic. They were emplaced shortly after the Svecokarelian orogeny.[9]
Sedimentary rocks
The oldest sedimentary rocks that outcrop in the Siljan area are of
Glaciation
During the last ice age the area was covered by a thick icesheet. The bedrock was sculpted by the ice, with the softer Palaeozoic sedimentary rocks being preferentially eroded. These erosional hollows are now occupied by lakes Siljan, Orsa, Skattungen and Ore.[8]
Oil and gas prospecting
In accordance with theories about
References
- ^ a b Glasby (2006)
- ^ "Siljan". Earth Impact Database. Planetary and Space Science Centre University of New Brunswick Fredericton. Retrieved 2017-10-09.
- S2CID 23316812. Retrieved 14 January 2023.
- . Retrieved 14 January 2023.
- S2CID 40588088. Retrieved 14 January 2023.
- ^ J.R. Morrow and C.A. Sandberg (2005). Revised Dating Of Alamo And Some Other Late Devonian Impacts In Relation To Resulting Mass Extinction, 68th Annual Meteoritical Society Meeting (2005)
- PMID 29934550.
- ^ a b c Ebbestad, J.O.R.; Högström A.E.S. (2007). "Ordovician of the Siljan District, Sweden" (PDF). IGCP503 Ordovician Palaeogeography and Palaeoclimate Regional Meeting 2007. Sveriges geologiska undersökning. pp. 7–22. Retrieved 12 July 2012.[permanent dead link]
- .
- . Retrieved 12 July 2012.
- PMID 1631089.
- ^ Bo Joffer, "Igrene förlänger runt Siljansringen, DT.se, 26 June 2012 (in Swedish). Accessed 13 July 2012."
- PMID 31628335.
- .
Bibliography
- Glasby, Geoffrey B. (2006), "Abiogenic Origin of Hydrocarbons: An Historical Overview" (PDF), Resource Geology, 56 (1): 85–98, S2CID 17968123, archived from the original(PDF) on 2008-02-26, retrieved 2012-07-13.
- Gold, Thomas (1992). "The deep, hot biosphere". PMID 1631089.
External links
- Sweden’s Siljan Ring at NASA Earth Observatory, July 21, 2021
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