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Petrographic classification of middle ordovician fossil meteorites from Sweden

Bridges, J. C.; Schmitz, Birger LU ; Hutchison, R.; Greenwood, R. C.; Tassinari, M and Franch, I. A. (2007) In Meteoritics and Planetary Science 42(10). p.1781-1789
Abstract
The maximum diameter of chromite (FeCr2O4) grains within L chondrites reflects the petrographic type of the sample. On the basis of our measurements of nine recent L chondrites, L3 chromite D-mac = 34-50 mu m, L4 = 87-150 mu m, L5 = 76-158 mu m, and L6 = 253-638 mu m. This variation reflects the crystallization of the chromite grains during parent body thermal metamorphism.We use this calibration to classify six fossil meteorites from the Middle Ordovician in Sweden as type 3 (or 4) to 6. The high flux of L chondrites at 470 Ma contained a range of petrographic types and may have had a higher proportion of lower petrographic type meteorites than are found in recent L chondrite falls. The fossil meteorites have in places preserved... (More)
The maximum diameter of chromite (FeCr2O4) grains within L chondrites reflects the petrographic type of the sample. On the basis of our measurements of nine recent L chondrites, L3 chromite D-mac = 34-50 mu m, L4 = 87-150 mu m, L5 = 76-158 mu m, and L6 = 253-638 mu m. This variation reflects the crystallization of the chromite grains during parent body thermal metamorphism.We use this calibration to classify six fossil meteorites from the Middle Ordovician in Sweden as type 3 (or 4) to 6. The high flux of L chondrites at 470 Ma contained a range of petrographic types and may have had a higher proportion of lower petrographic type meteorites than are found in recent L chondrite falls. The fossil meteorites have in places preserved recognizable chondrule textures, including porphyritic olivine, barred olivine, and radiating pyroxene. A large relict clast and fusion crust have also been tentatively identified in one fossil meteorite. Apart from chromite, all of the original meteorite minerals have been replaced by carbonate (and sheet silicate and sulfate) during diagenesis within the limestone host. The preservation of chondrule definition has allowed us to measure the mean diameters of relict chondrules. The range (0.4-0.6 mm) is consistent with measurements made in the same way on recent L chondrites. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
in
Meteoritics and Planetary Science
volume
42
issue
10
pages
1781 - 1789
publisher
Wiley-Blackwell
external identifiers
  • wos:000252529700007
  • scopus:38949120516
ISSN
1086-9379
DOI
10.1111/j.1945-5100.2007.tb00537.x
language
English
LU publication?
yes
id
5a5c8ea5-6058-46d4-b1b5-9a2281ef5412 (old id 1407597)
date added to LUP
2009-05-29 14:32:46
date last changed
2017-01-01 07:00:32
@article{5a5c8ea5-6058-46d4-b1b5-9a2281ef5412,
  abstract     = {The maximum diameter of chromite (FeCr2O4) grains within L chondrites reflects the petrographic type of the sample. On the basis of our measurements of nine recent L chondrites, L3 chromite D-mac = 34-50 mu m, L4 = 87-150 mu m, L5 = 76-158 mu m, and L6 = 253-638 mu m. This variation reflects the crystallization of the chromite grains during parent body thermal metamorphism.We use this calibration to classify six fossil meteorites from the Middle Ordovician in Sweden as type 3 (or 4) to 6. The high flux of L chondrites at 470 Ma contained a range of petrographic types and may have had a higher proportion of lower petrographic type meteorites than are found in recent L chondrite falls. The fossil meteorites have in places preserved recognizable chondrule textures, including porphyritic olivine, barred olivine, and radiating pyroxene. A large relict clast and fusion crust have also been tentatively identified in one fossil meteorite. Apart from chromite, all of the original meteorite minerals have been replaced by carbonate (and sheet silicate and sulfate) during diagenesis within the limestone host. The preservation of chondrule definition has allowed us to measure the mean diameters of relict chondrules. The range (0.4-0.6 mm) is consistent with measurements made in the same way on recent L chondrites.},
  author       = {Bridges, J. C. and Schmitz, Birger and Hutchison, R. and Greenwood, R. C. and Tassinari, M and Franch, I. A.},
  issn         = {1086-9379},
  language     = {eng},
  number       = {10},
  pages        = {1781--1789},
  publisher    = {Wiley-Blackwell},
  series       = {Meteoritics and Planetary Science},
  title        = {Petrographic classification of middle ordovician fossil meteorites from Sweden},
  url          = {http://dx.doi.org/10.1111/j.1945-5100.2007.tb00537.x},
  volume       = {42},
  year         = {2007},
}