Rock magnetic and paleomagnetic study of the Keurusselkä impact structure, central Finland
Abstract– There are 31 proven impact structures in Fennoscandia—one of the most densely crater‐populated areas of the Earth. The recently discovered Keurusselkä impact structure (62°08′ N, 24°37′ E) is located within the Central Finland Granitoid Complex, which formed 1890–1860 Ma ago during the Sve...
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crwiley:10.1111/j.1945-5100.2011.01255.x 2023-12-03T10:22:34+01:00 Rock magnetic and paleomagnetic study of the Keurusselkä impact structure, central Finland RAISKILA, Selen SALMINEN, Johanna ELBRA, Tiiu PESONEN, Lauri J. 2011 http://dx.doi.org/10.1111/j.1945-5100.2011.01255.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1945-5100.2011.01255.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1945-5100.2011.01255.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Meteoritics & Planetary Science volume 46, issue 11, page 1670-1687 ISSN 1086-9379 1945-5100 Space and Planetary Science Geophysics journal-article 2011 crwiley https://doi.org/10.1111/j.1945-5100.2011.01255.x 2023-11-09T13:24:15Z Abstract– There are 31 proven impact structures in Fennoscandia—one of the most densely crater‐populated areas of the Earth. The recently discovered Keurusselkä impact structure (62°08′ N, 24°37′ E) is located within the Central Finland Granitoid Complex, which formed 1890–1860 Ma ago during the Svecofennian orogeny. It is a deeply eroded complex crater that yields in situ shatter cones with evidence of shock metamorphism, e.g., planar deformation features in quartz. New petrophysical and rock magnetic results of shocked and unshocked target rocks of various lithologies combined with paleomagnetic studies are presented. The suggested central uplift with shatter cones is characterized by increased magnetization and susceptibility. The presence of magnetite and pyrrhotite was observed as carriers for the remanent magnetization. Four different remanent magnetization directions were isolated: (1) a characteristic Svecofennian target rock component A with a mean direction of D = 334.8°, I = 45.6°, α 95 = 14.9° yielding a pole (Plat = 51.1°, Plon = 241.9°, A 95 = 15.1°), (2) component B, D = 42.4°, I = 64.1°, α 95 = 8.4° yielding a pole (Plat = 61.0°, Plon = 129.1°, A 95 = 10.6°), (3) component C ( D = 159.5°, I = 65.4°, α 95 = 10.7°) yielding a pole (Plat = 21.0°, Plon = 39.3°, A 95 = 15.6°), and (4) component E ( D = 275.5°, I = 62.0°, α 95 = 14.4°) yielding a pole (Plat = 39.7°, Plon = 314.3°, A 95 = 19.7°). Components C and E are considered much younger, possibly Neoproterozoic overprints, compared with the components A and B. The pole of component B corresponds with the 1120 Ma pole of Salla diabase dyke and is in agreement with the 40 Ar/ 39 Ar age of 1140 Ma from a pseudotachylitic breccia vein in a central part of the structure. Therefore, component B could be related to the impact, and thus represent the impact age. Article in Journal/Newspaper Fennoscandia Wiley Online Library (via Crossref) Salla ENVELOPE(28.667,28.667,66.833,66.833) Target Rock ENVELOPE(-92.851,-92.851,63.876,63.876) Meteoritics & Planetary Science 46 11 1670 1687 |
institution |
Open Polar |
collection |
Wiley Online Library (via Crossref) |
op_collection_id |
crwiley |
language |
English |
topic |
Space and Planetary Science Geophysics |
spellingShingle |
Space and Planetary Science Geophysics RAISKILA, Selen SALMINEN, Johanna ELBRA, Tiiu PESONEN, Lauri J. Rock magnetic and paleomagnetic study of the Keurusselkä impact structure, central Finland |
topic_facet |
Space and Planetary Science Geophysics |
description |
Abstract– There are 31 proven impact structures in Fennoscandia—one of the most densely crater‐populated areas of the Earth. The recently discovered Keurusselkä impact structure (62°08′ N, 24°37′ E) is located within the Central Finland Granitoid Complex, which formed 1890–1860 Ma ago during the Svecofennian orogeny. It is a deeply eroded complex crater that yields in situ shatter cones with evidence of shock metamorphism, e.g., planar deformation features in quartz. New petrophysical and rock magnetic results of shocked and unshocked target rocks of various lithologies combined with paleomagnetic studies are presented. The suggested central uplift with shatter cones is characterized by increased magnetization and susceptibility. The presence of magnetite and pyrrhotite was observed as carriers for the remanent magnetization. Four different remanent magnetization directions were isolated: (1) a characteristic Svecofennian target rock component A with a mean direction of D = 334.8°, I = 45.6°, α 95 = 14.9° yielding a pole (Plat = 51.1°, Plon = 241.9°, A 95 = 15.1°), (2) component B, D = 42.4°, I = 64.1°, α 95 = 8.4° yielding a pole (Plat = 61.0°, Plon = 129.1°, A 95 = 10.6°), (3) component C ( D = 159.5°, I = 65.4°, α 95 = 10.7°) yielding a pole (Plat = 21.0°, Plon = 39.3°, A 95 = 15.6°), and (4) component E ( D = 275.5°, I = 62.0°, α 95 = 14.4°) yielding a pole (Plat = 39.7°, Plon = 314.3°, A 95 = 19.7°). Components C and E are considered much younger, possibly Neoproterozoic overprints, compared with the components A and B. The pole of component B corresponds with the 1120 Ma pole of Salla diabase dyke and is in agreement with the 40 Ar/ 39 Ar age of 1140 Ma from a pseudotachylitic breccia vein in a central part of the structure. Therefore, component B could be related to the impact, and thus represent the impact age. |
format |
Article in Journal/Newspaper |
author |
RAISKILA, Selen SALMINEN, Johanna ELBRA, Tiiu PESONEN, Lauri J. |
author_facet |
RAISKILA, Selen SALMINEN, Johanna ELBRA, Tiiu PESONEN, Lauri J. |
author_sort |
RAISKILA, Selen |
title |
Rock magnetic and paleomagnetic study of the Keurusselkä impact structure, central Finland |
title_short |
Rock magnetic and paleomagnetic study of the Keurusselkä impact structure, central Finland |
title_full |
Rock magnetic and paleomagnetic study of the Keurusselkä impact structure, central Finland |
title_fullStr |
Rock magnetic and paleomagnetic study of the Keurusselkä impact structure, central Finland |
title_full_unstemmed |
Rock magnetic and paleomagnetic study of the Keurusselkä impact structure, central Finland |
title_sort |
rock magnetic and paleomagnetic study of the keurusselkä impact structure, central finland |
publisher |
Wiley |
publishDate |
2011 |
url |
http://dx.doi.org/10.1111/j.1945-5100.2011.01255.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1945-5100.2011.01255.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1945-5100.2011.01255.x |
long_lat |
ENVELOPE(28.667,28.667,66.833,66.833) ENVELOPE(-92.851,-92.851,63.876,63.876) |
geographic |
Salla Target Rock |
geographic_facet |
Salla Target Rock |
genre |
Fennoscandia |
genre_facet |
Fennoscandia |
op_source |
Meteoritics & Planetary Science volume 46, issue 11, page 1670-1687 ISSN 1086-9379 1945-5100 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/j.1945-5100.2011.01255.x |
container_title |
Meteoritics & Planetary Science |
container_volume |
46 |
container_issue |
11 |
container_start_page |
1670 |
op_container_end_page |
1687 |
_version_ |
1784270521577242624 |