Lockne - Hypervelocity Impact Crater

Alternate Names Lockne- Malingen Doublet
Local Language
Coordinates 63° 2' 17" N; 14° 50' 43" E
Notes
  1. 20 km S of Östersund, Sweden.
Country Sweden
Region Jämtland
Date Confirmed 1992
Notes
  1. First interpretted the breccias of this area to be from impact cratering in a shallow sea (Wickman,1988). Later, an impact site was supported by the discovery of PDFs in quartz grains and local iridium enrichment (Lindström and Strukell, 1992).
Buried? Yes
Notes
  1. Partially buried by a Caledonian overthrust, which has served to protect the crater.
Drilled? Yes
Notes
  1. 6 drill cores located within the structure (Lindström et al., 1996).
Target Type Mixed
Notes
  1. Ordovician shales and limestones. Cambrian conglomerate shales, sandstones and limestones. Proterozoic granites, dolerites and volcanites (Lindström and Sturkell, 1992). Impact ocurred at sea. Water depth was ~0.5km (Ormo et al., 2014). Target seabed consisted of 0.08km of Cambrian and Ordovician sediments; approximately one-half was lithified limestone, the other soft claystone and semi-lithified limestone. All sat upon a peneplain cut into crystalline basement ((Lindstrom et al., 2005). See also: (Holm-Alwmark, 2021).
Sub-Type Limestone, Sandstone, Shale, Granite, Volcanites
Apparent Crater Diameter (km) 13.5 km
Age (Ma) ~455
Notes :
  1. Based on chitinozoan biostratigraphy, the Lockne and Malingen events have the same age of approximately 455 Ma (Grahn et al., 1996) (Grahn, 1997) (Ormo et al., 2014). Additional age constraints: Based on post-impact sediments, age is >455 Ma (Grahm and Nolvak, 1993).

Method :
  1. Biostratigraphy
Impactor Type L chondrite
Notes
  1. See (Alwmark and Schmitz, 2007) and (Schmitz et al., 2011) as referenced in (Alwmark et al., 2015).

Advanced Data Fields

Notes

Erosion
3
  1. Some evidence of a topographic rim remains. Crater filled by Ordovician limestone. Some ejecta preserved in a ~50m thick unit on the brim; in parts this consists of an overturned flap of target rock (Holm-Alwmark, 2021).
Final Rim Diameter
Unknown
Apparent Rim Diameter
13.5 km
  1. An inner crater of 7.5 km surrounded by eroded area of 3 km wide (outer crater), which yields a total diameter of 13.5 km (Lindström et al., 1996).
Rim Reliability Index
2
  1. Area is complicated by Caledonian tectonics (Lindström et al., 1991). Actual morphology type is unknown but is assumed to be complex. Central uplift indicated by gravimetric and magnetometric reconstructions; supported by height of crystalline rock found in drill core; true dimensions unknown (Holm-Alwmark, 2021).
Crater Morphology
Complex
Central Uplift Diameter
km
Central Uplift Height
Unknown
Uplift Reliability Index
Structural Uplift
Unknown
Thickness of Seds
0.08
Target Age
Precambrian Palaeozoic
Marine
Yes
Impactor Type
L chondrite
  1. See (Alwmark and Schmitz, 2007) and (Schmitz et al., 2011) as referenced in (Alwmark et al., 2015).
Other Shock Metamorphism
Linguinite
  1. High-pressure linguinite found at mineral interfaces between augite and labradorite in samples of diabase (Agarwal et al., 2016).
Shatter Cones
No
  1. No shatter cones reported at Lockne impact structure (Ormo, pers. comm., 2010).
Planar Fractures
No
Planar Deformation Features
Yes
  1. PDF in quartz grains (Therriault and Lindstrom, 1995).
Diaplectic Glass
No
Coesite
No
Stisovite
No
Crater Fill
LB, MB
  1. The brecciated parauthocthonous crystalline basement is named Tandsbyn Breccia (Lindstrom and Sturkell, 1992) (Lindstrom et al., 1996). Resurge deposits at Lockne (also referred to as tsunami deposits) consist of: (1) a lower coarse-grained, polymict breccia with clasts of limestones and crystalline rocks (Lockne Breccia), overlain by (2) a finer-grained (arenitic to silty), normally graded bedded breccia member named Loftarstone, with limestone clasts, fossils and silicate-carbonate melt fragments (Ormo et al., 2007) (Sjöqvist et al., 2012) (Sjöqvist et al., 2016). Small lenses of carbonate-silicate impact melt fragments/clasts have been documented in the Loftarstone (Sjöqvist et al., 2012). The Loftarstone has been observed as far as 45 km from the crater (Sjöqvist et al., 2016). The Lockne-2 drill hole cut 91 m of polymict, matrix-supported breccias with limestone and basement rock clasts (gravel to boulder sizes), interpreted to had formed before the resurge and which could represt fall-back material (Ormo et al., 2007). Ejecta is mainly dominated by Tandsbyn Breccia clasts, however, mafic ejecta also occurs. The mafic impact breccia occurs mainly as a coherent thin domain within a larger block of granitic breccia, which we interpret as a result of the in situ brecciation of a dolerite sill within granitic bedrock (Sjoqvist, 2016).
Proximal Ejecta
LB
Distal Ejecta
Dykes
Volume of Melt
Depth of Melting

References

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M Lindstrom, E F F Sturkell, R Tornberg, J Ormö (1996) The marine impact crater at Lockne, central Sweden, GFF 118(4), p. 193-206, Geological Society of Sweden, Stockholm, url

E F F Sturkell, A Ekelund, R Tornberg (1998) Gravity modelling of Lockne, a marine impact structure in Jamtland, central Sweden, Tectonophysics 296(3-4), p. 421-435, Elsevier, Amsterdam, url

E F F Sturkell (1998) Resurge morphology of the marine Lockne impact crater, Jamltland, central Sweden, Geological Magazine 135(1), p. 121-127, Cambridge University Press, London, doi:http://dx.doi.org/10.1017/S0016756897007875

E F F Sturkell (1998) Impact-related Ir anomaly in the Middle Ordovician Lockne impact structure, Jamtland, Sweden, GFF 120(4), p. 333-336, Geological Society of Sweden, Stockholm, url

E F F Sturkell, J Ormö (1998) Magnetometry of the marine, Ordovician Lockne impact structure, Jamtland, Sweden, Journal of Applied Geophysics 38(3), p. 195-207, Elsevier, Amsterdam, url

E Sturkell, J Ormö, J Kolvak, A Wallin (2000) Distant ejecta from the Lockne marine-target impact crater, Sweden, Meteoritics & Planetary Science 35(5), p. 929-936, Meteoritical Society, Fayetteville, AR, url

I von Dalwigk, J Ormö (2001) Formation of resurge gullies at impacts at sea: The Lockne Crater, Sweden, Meteoritics & Planetary Science 36(3), p. 359-369, Meteoritical Society, Fayetteville, AR, url

J Ormö, H Miyamoto (2002) Computer modelling of the water resurge at a marine impact: The Lockne Crater, Sweden, Deep-Sea Research. Part II: Topical Studies in Oceanography 49(6), p. 983-994, Pergamon, Oxford, url, doi:http://dx.doi.org/10.1016/S0967-0645(01)00143-6

E Sturkell, M Lindstrom (2004) The target peneplain of the Lockne impact, Meteoritics & Planetary Science 39(10), p. 1721-1731, Meteoritical Society, Fayetteville, AR, url

C Alwmark, B Schmitz (2006) Extraterrestrial chromite in the Ordovician Lockne impact structure, central Sweden, Meteoritics & Planetary Science 41, Supple, p. 1, Meteoritical Society, Fayetteville, AR, url

C Alwmark, B Schmitz (2007) Extraterrestrial chromite in the resurge deposits of the early Late Ordovician Lockne Crater, central Sweden, Earth and Planetary Science Letters 253(1-2), p. 291-303, Elsevier, Amsterdam, url, doi:http://dx.doi.org/10.1016/j.epsl.2006.10.034

T Kenkmann, F Kiebach, M Rosenau, U Raschke, A Pigowske, K Mittelhaus, D Eue (2007) Coupled effects of impact and orogeny: Is the marine Lockne Crater, Sweden, pristine?, Meteoritics & Planetary Science 42(11), Jens Ormo, Alexander Deutsch (ed.), p. 1995-2012, Meteoritical Society, Fayetteville, AR, url

M Lindstrom, J Ormö, E Sturkell (2008) Water-blow and resurge breccias at the Lockne marine-target impact structure, Special Paper - Geological Society of America 437, Kevin R Evans, J Wright Horton Jr., David T King Jr., Jared R Morrow (ed.), p. 43-54, Geological Society of America (GSA), Boulder, CO, url, doi:http://dx.doi.org/10.1130/208.2437(03

A E S Högström, E Sturkell, J O R Ebbestad, M Lindström, J Ormö (2010) Concentric impact structures in the Palaeozoic of Sweden – The Lockne and Siljan craters, GFF 132(1), p. 65-70, url, doi:10.1080/11035890903469971

B Schmitz, P R Heck, C Alwmark, N T Kita, M M M Meier, B Peucker-Ehrenbrink, T Ushikubo, J W Valley (2011) Determining the impactor of the Ordovician Lockne Crater: Oxygen and neon isotopes in chromite versus sedimentary PGE signatures, Earth and Planetary Science Letters 306(3-4), p. 149-155, Elsevier, Amsterdam, url, doi:http://dx.doi.org/10.1016/j.epsl.2011.04.028

C Broman, E Sturkell, A E Fallick (2011) Oxygen isotopes and implications for the cavity-grown quartz crystals in the Lockne impact structure, Sweden, GFF 133(1-2), p. 101-107, url, doi:10.1080/11035897.2011.597512

J Ormö, A P Rossi, K R Housen (2013) A new method to determine the direction of impact: Asymmetry of concentric impact craters as observed in the field (Lockne), on Mars, in experiments, and simulations, Meteoritics & Planetary Science 48(3), p. 403-419, Meteoritical Society, Fayetteville, AR, url, doi:http://dx.doi.org/10.1111/maps.12065

E Sturkell, J Ormö, A Lepinette (2013) Early modification stage (preresurge) sediment mobilization in the Lockne concentric, marine-target crater, Sweden, Meteoritics & Planetary Science 48(3), p. 321-338, Meteoritical Society, Fayetteville, AR, url, doi:http://dx.doi.org/10.1111/maps.12058

M Ivarsson, C Broman, E Sturkell, J Ormö, S Siljeström, M van Zuilen, S Bengtson (2013) Fungal colonization of an Ordovician impact-induced hydrothermal system, Scientific Reports 3(1), url, doi:10.1038/srep03487

J Ormö, E Sturkell, J Nõlvak, I Melero-Asensio, Å Frisk, T Wikström (2014) The geology of the Målingen structure: A probable doublet to the Lockne marine-target impact crater, central Sweden, Meteoritics & Planetary Science 49(3), url, doi:10.1111/maps.12251

A Agarwal, B Reznik, A Kontny, S Heissler, F Schilling (2016) Lingunite — a high-pressure plagioclase polymorph at mineral interfaces in doleritic rock of the Lockne impact structure (Sweden), Scientific Reports 6(1), url, doi:10.1038/srep25991

A S L Sjöqvist, P Lindgren, E F F Sturkell, K J Hogmalm, C Broman, M Ivarsson, M R Lee (2017) Shock metamorphism and hydrothermal alteration of mafic impact ejecta from the Lockne impact structure, Sweden, GFF 139(2), url, doi:10.1080/11035897.2016.1227361