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The mid-Ordovician Osmussaar breccia in Estonia linked to the disruption of the L-chondrite parent body in the asteroid belt

Alwmark, Carl LU ; Schmitz, Birger LU and Kirsimaee, Kalle (2010) In Geological Society of America Bulletin 122(7-8). p.1039-1046
Abstract
The Middle Ordovician (466 Ma) Osmussaar breccia, situated along the northwestern coast of Estonia, is rich in angular chromite grains of extraterrestrial origin (>13 grains kg(-1)) and shocked quartz. The angularity of the chromite grains implies that they have not been transported or reworked to any large extent, connoting that the brecciation is the result of a contemporary impactor, either as a direct consequence of the impact or as a result of an earthquake triggered by the impact, and thus is not, as previously suggested, redeposited material from the nearby similar to 70 m.y. older Neugrund impact structure. The chemical composition of the chromite indicates that the impactor was an ordinary chondrite of L-type, which concurs... (More)
The Middle Ordovician (466 Ma) Osmussaar breccia, situated along the northwestern coast of Estonia, is rich in angular chromite grains of extraterrestrial origin (>13 grains kg(-1)) and shocked quartz. The angularity of the chromite grains implies that they have not been transported or reworked to any large extent, connoting that the brecciation is the result of a contemporary impactor, either as a direct consequence of the impact or as a result of an earthquake triggered by the impact, and thus is not, as previously suggested, redeposited material from the nearby similar to 70 m.y. older Neugrund impact structure. The chemical composition of the chromite indicates that the impactor was an ordinary chondrite of L-type, which concurs well with the hypothesis that the influx of large bodies to Earth increased during this period due to the breakup of the L-chondrite parent body. This in turn gives support to the recent suggestion that abundant coeval mega-breccias worldwide are impact triggered. The presence of extraterrestrial chromite also strengthens the theory that physical pieces of a large celestial body can survive upon impact with Earth. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Geological Society of America Bulletin
volume
122
issue
7-8
pages
1039 - 1046
publisher
Geological Society of America
external identifiers
  • wos:000278351300006
  • scopus:77954025811
ISSN
0016-7606
DOI
10.1130/B30040.1
language
English
LU publication?
yes
id
27cc9c6e-2fde-4e1e-9a6d-65b512d2bb34 (old id 1632208)
date added to LUP
2010-07-21 09:48:11
date last changed
2018-05-29 10:34:59
@article{27cc9c6e-2fde-4e1e-9a6d-65b512d2bb34,
  abstract     = {The Middle Ordovician (466 Ma) Osmussaar breccia, situated along the northwestern coast of Estonia, is rich in angular chromite grains of extraterrestrial origin (>13 grains kg(-1)) and shocked quartz. The angularity of the chromite grains implies that they have not been transported or reworked to any large extent, connoting that the brecciation is the result of a contemporary impactor, either as a direct consequence of the impact or as a result of an earthquake triggered by the impact, and thus is not, as previously suggested, redeposited material from the nearby similar to 70 m.y. older Neugrund impact structure. The chemical composition of the chromite indicates that the impactor was an ordinary chondrite of L-type, which concurs well with the hypothesis that the influx of large bodies to Earth increased during this period due to the breakup of the L-chondrite parent body. This in turn gives support to the recent suggestion that abundant coeval mega-breccias worldwide are impact triggered. The presence of extraterrestrial chromite also strengthens the theory that physical pieces of a large celestial body can survive upon impact with Earth.},
  author       = {Alwmark, Carl and Schmitz, Birger and Kirsimaee, Kalle},
  issn         = {0016-7606},
  language     = {eng},
  number       = {7-8},
  pages        = {1039--1046},
  publisher    = {Geological Society of America},
  series       = {Geological Society of America Bulletin},
  title        = {The mid-Ordovician Osmussaar breccia in Estonia linked to the disruption of the L-chondrite parent body in the asteroid belt},
  url          = {http://dx.doi.org/10.1130/B30040.1},
  volume       = {122},
  year         = {2010},
}