Advanced

The origin of the Brunflo fossil meteorite and extraterrestrial chromite in mid-Ordovician limestone from the Garde quarry (Jamtland, central Sweden)

Alwmark, Carl LU and Schmitz, Birger LU (2009) In Meteoritics and Planetary Science 44(1). p.95-106
Abstract
The Brunflo fossil meteorite was found in the 1950s in mid-Ordovician marine limestone in the Garde quarry in Jamtland. It originates from strata that are about 5 million years younger than similar limestone that more recently has yielded >50 fossil meteorites in the Thorsberg quarry at Kinnekulle, 600 km to the south. Based primarily on the low TiO2 content (about 1.8 wt%) of its relict chromite the Brunflo meteorite had been tentatively classified as an H chondrite. The meteorite hence appears to be an anomaly in relation to the Kinnekulle meteorites, in which chromite composition, chondrule mean diameter and oxygen isotopic composition all indicate an L-chondritic origin, reflecting an enhanced flux of meteorites to Earth following... (More)
The Brunflo fossil meteorite was found in the 1950s in mid-Ordovician marine limestone in the Garde quarry in Jamtland. It originates from strata that are about 5 million years younger than similar limestone that more recently has yielded >50 fossil meteorites in the Thorsberg quarry at Kinnekulle, 600 km to the south. Based primarily on the low TiO2 content (about 1.8 wt%) of its relict chromite the Brunflo meteorite had been tentatively classified as an H chondrite. The meteorite hence appears to be an anomaly in relation to the Kinnekulle meteorites, in which chromite composition, chondrule mean diameter and oxygen isotopic composition all indicate an L-chondritic origin, reflecting an enhanced flux of meteorites to Earth following the disruption of the L chondrite parent body 470 Ma. New chondrule-size measurements for the Brunflo meteorite indicate that it too is an L chondrite, related to the same parent-body breakup. Chromite maximum diameters and well-defined chondrule structures further show that Brunflo belongs to the L4 or L5 type. Chromites in recently fallen L4 chondrites commonly have low TiO2 contents similar to the Brunflo chromites, adding support for Brunflo being an L4 chondrite. The limestone in the Circle quarry is relatively rich (about 0.45 grain kg(-1)) in sediment-dispersed extraterrestrial chromite grains (>63 mu m) with chemical composition similar to those in L chondrites and the limestone (1-3 grains kg(-1)) at Kinnekulle, suggesting that the enhanced flux of L chondrites prevailed, although somewhat diminished, at the time when the Brunflo meteorite fell. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Meteoritics and Planetary Science
volume
44
issue
1
pages
95 - 106
publisher
Wiley-Blackwell
external identifiers
  • wos:000264476300008
  • scopus:64549097249
ISSN
1086-9379
language
English
LU publication?
yes
id
5ef62210-5720-41d9-82b8-bcb27311fcda (old id 1401770)
date added to LUP
2009-06-15 10:42:27
date last changed
2017-09-24 04:09:38
@article{5ef62210-5720-41d9-82b8-bcb27311fcda,
  abstract     = {The Brunflo fossil meteorite was found in the 1950s in mid-Ordovician marine limestone in the Garde quarry in Jamtland. It originates from strata that are about 5 million years younger than similar limestone that more recently has yielded >50 fossil meteorites in the Thorsberg quarry at Kinnekulle, 600 km to the south. Based primarily on the low TiO2 content (about 1.8 wt%) of its relict chromite the Brunflo meteorite had been tentatively classified as an H chondrite. The meteorite hence appears to be an anomaly in relation to the Kinnekulle meteorites, in which chromite composition, chondrule mean diameter and oxygen isotopic composition all indicate an L-chondritic origin, reflecting an enhanced flux of meteorites to Earth following the disruption of the L chondrite parent body 470 Ma. New chondrule-size measurements for the Brunflo meteorite indicate that it too is an L chondrite, related to the same parent-body breakup. Chromite maximum diameters and well-defined chondrule structures further show that Brunflo belongs to the L4 or L5 type. Chromites in recently fallen L4 chondrites commonly have low TiO2 contents similar to the Brunflo chromites, adding support for Brunflo being an L4 chondrite. The limestone in the Circle quarry is relatively rich (about 0.45 grain kg(-1)) in sediment-dispersed extraterrestrial chromite grains (>63 mu m) with chemical composition similar to those in L chondrites and the limestone (1-3 grains kg(-1)) at Kinnekulle, suggesting that the enhanced flux of L chondrites prevailed, although somewhat diminished, at the time when the Brunflo meteorite fell.},
  author       = {Alwmark, Carl and Schmitz, Birger},
  issn         = {1086-9379},
  language     = {eng},
  number       = {1},
  pages        = {95--106},
  publisher    = {Wiley-Blackwell},
  series       = {Meteoritics and Planetary Science},
  title        = {The origin of the Brunflo fossil meteorite and extraterrestrial chromite in mid-Ordovician limestone from the Garde quarry (Jamtland, central Sweden)},
  volume       = {44},
  year         = {2009},
}