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Shocked quartz grains from the Malingen structure, Sweden-Evidence for a twin crater of the Lockne impact structure

Alwmark, Carl LU ; Alwmark, Sanna LU ; Ormoe, J. and Sturkell, E. (2014) In Meteoritics and Planetary Science 49(6). p.1076-1082
Abstract
The Malingen structure in Sweden has for a long time been suspected to be the result of an impact; however, no hard evidence, i.e., shock metamorphic features or traces of the impactor, has so far been presented. Here we show that quartz grains displaying planar deformation features (PDFs) oriented along crystallographic planes typical for shock metamorphism are present in drill core samples from the structure. The shocked material was recovered from basement breccias, below the sediment infill, and the distribution of the orientation of the shock-produced PDFs indicates that the studied material experienced low shock pressures. Based on our findings, we can exclude that the material is transported from the nearby Lockne impact structure,... (More)
The Malingen structure in Sweden has for a long time been suspected to be the result of an impact; however, no hard evidence, i.e., shock metamorphic features or traces of the impactor, has so far been presented. Here we show that quartz grains displaying planar deformation features (PDFs) oriented along crystallographic planes typical for shock metamorphism are present in drill core samples from the structure. The shocked material was recovered from basement breccias, below the sediment infill, and the distribution of the orientation of the shock-produced PDFs indicates that the studied material experienced low shock pressures. Based on our findings, we can exclude that the material is transported from the nearby Lockne impact structure, which means that the Malingen structure is a separate impact structure, the seventh confirmed impact structure in Sweden. Furthermore, sedimentological and biostratigraphic aspects of the deposits that fill the depression at Malingen are very similar to features at the Lockne impact structure. This implies a coeval formation age and thus also the confirmation of the first known marine target doublet impact craters on Earth (i.e., the Lockne-Malingen pair). (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Meteoritics and Planetary Science
volume
49
issue
6
pages
1076 - 1082
publisher
Wiley-Blackwell
external identifiers
  • wos:000337625200009
  • scopus:84902280765
ISSN
1086-9379
DOI
10.1111/maps.12314
language
English
LU publication?
yes
id
c6c248bc-3301-484c-bcf9-edee240a4c22 (old id 4609676)
date added to LUP
2014-08-25 09:49:26
date last changed
2017-01-01 06:27:10
@article{c6c248bc-3301-484c-bcf9-edee240a4c22,
  abstract     = {The Malingen structure in Sweden has for a long time been suspected to be the result of an impact; however, no hard evidence, i.e., shock metamorphic features or traces of the impactor, has so far been presented. Here we show that quartz grains displaying planar deformation features (PDFs) oriented along crystallographic planes typical for shock metamorphism are present in drill core samples from the structure. The shocked material was recovered from basement breccias, below the sediment infill, and the distribution of the orientation of the shock-produced PDFs indicates that the studied material experienced low shock pressures. Based on our findings, we can exclude that the material is transported from the nearby Lockne impact structure, which means that the Malingen structure is a separate impact structure, the seventh confirmed impact structure in Sweden. Furthermore, sedimentological and biostratigraphic aspects of the deposits that fill the depression at Malingen are very similar to features at the Lockne impact structure. This implies a coeval formation age and thus also the confirmation of the first known marine target doublet impact craters on Earth (i.e., the Lockne-Malingen pair).},
  author       = {Alwmark, Carl and Alwmark, Sanna and Ormoe, J. and Sturkell, E.},
  issn         = {1086-9379},
  language     = {eng},
  number       = {6},
  pages        = {1076--1082},
  publisher    = {Wiley-Blackwell},
  series       = {Meteoritics and Planetary Science},
  title        = {Shocked quartz grains from the Malingen structure, Sweden-Evidence for a twin crater of the Lockne impact structure},
  url          = {http://dx.doi.org/10.1111/maps.12314},
  volume       = {49},
  year         = {2014},
}