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Metamorphic zircon formation at the transition from gabbro to eclogite in Trollheimen-Surnadalen, Norwegian Caledonides

Beckman, Victoria LU ; Möller, Charlotte LU ; Söderlund, Ulf LU ; Corfu, Fernando; Pallon, Jan LU and Chamberlain, Kevin R. (2014) In Geological Society Special Publication 390. p.403-424
Abstract
A transition from gabbro to eclogite has been investigated at Vinddoldalen in south-central Norway, with the aim to link reaction textures to metamorphic zircon growth and to obtain a direct U-Pb zircon age of the metamorphic process. In the different rocks of the transition zone zircon occurs as (I) igneous prismatic grains, (II) metamorphic polycrystalline rims and pseudomorphs after baddeleyite, and (III) as tiny (< 10 mu m) bead-like zircon grains. Textural relations suggest that type II zircon formed by breakdown of baddeleyite in the presence of silica, whereas Fe-Ti oxides were the main Zr source for the type III zircon. Subsolidus liberation of Zr and formation of bead zircon took place by oxyexsolution of titanomagnetite during... (More)
A transition from gabbro to eclogite has been investigated at Vinddoldalen in south-central Norway, with the aim to link reaction textures to metamorphic zircon growth and to obtain a direct U-Pb zircon age of the metamorphic process. In the different rocks of the transition zone zircon occurs as (I) igneous prismatic grains, (II) metamorphic polycrystalline rims and pseudomorphs after baddeleyite, and (III) as tiny (< 10 mu m) bead-like zircon grains. Textural relations suggest that type II zircon formed by breakdown of baddeleyite in the presence of silica, whereas Fe-Ti oxides were the main Zr source for the type III zircon. Subsolidus liberation of Zr and formation of bead zircon took place by oxyexsolution of titanomagnetite during fluid-assisted metamorphism, and by resorption of Fe-Ti oxide in rock domains that were completely recrystallized to eclogite. SIMS (secondary ion mass spectrometry) and TIMS (thermal ionization mass spectrometry) dating provides comparable U-Pb ages of magmatic zircon and baddeleyite. Baddeleyite (TIMS) yielded an age of 1457 +/- 11 Ma for the gabbro emplacement. Bead-type metamorphic zircon from eclogite gave 425 +/- 10 Ma (TIMS) dating the metamorphic transition from gabbro to eclogite in the upper basement of the Lower Allochthon in the south-central Scandinavian Caledonides. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Geological Society Special Publication
volume
390
pages
403 - 424
publisher
Geological Society of London
external identifiers
  • wos:000340172100017
  • scopus:84897940570
ISSN
2041-4927
DOI
10.1144/SP390.26
language
English
LU publication?
yes
id
23c08738-127e-481e-9c51-bbe2eb849c67 (old id 4665642)
date added to LUP
2014-09-25 14:54:21
date last changed
2017-08-20 03:07:03
@article{23c08738-127e-481e-9c51-bbe2eb849c67,
  abstract     = {A transition from gabbro to eclogite has been investigated at Vinddoldalen in south-central Norway, with the aim to link reaction textures to metamorphic zircon growth and to obtain a direct U-Pb zircon age of the metamorphic process. In the different rocks of the transition zone zircon occurs as (I) igneous prismatic grains, (II) metamorphic polycrystalline rims and pseudomorphs after baddeleyite, and (III) as tiny (&lt; 10 mu m) bead-like zircon grains. Textural relations suggest that type II zircon formed by breakdown of baddeleyite in the presence of silica, whereas Fe-Ti oxides were the main Zr source for the type III zircon. Subsolidus liberation of Zr and formation of bead zircon took place by oxyexsolution of titanomagnetite during fluid-assisted metamorphism, and by resorption of Fe-Ti oxide in rock domains that were completely recrystallized to eclogite. SIMS (secondary ion mass spectrometry) and TIMS (thermal ionization mass spectrometry) dating provides comparable U-Pb ages of magmatic zircon and baddeleyite. Baddeleyite (TIMS) yielded an age of 1457 +/- 11 Ma for the gabbro emplacement. Bead-type metamorphic zircon from eclogite gave 425 +/- 10 Ma (TIMS) dating the metamorphic transition from gabbro to eclogite in the upper basement of the Lower Allochthon in the south-central Scandinavian Caledonides.},
  author       = {Beckman, Victoria and Möller, Charlotte and Söderlund, Ulf and Corfu, Fernando and Pallon, Jan and Chamberlain, Kevin R.},
  issn         = {2041-4927},
  language     = {eng},
  pages        = {403--424},
  publisher    = {Geological Society of London},
  series       = {Geological Society Special Publication},
  title        = {Metamorphic zircon formation at the transition from gabbro to eclogite in Trollheimen-Surnadalen, Norwegian Caledonides},
  url          = {http://dx.doi.org/10.1144/SP390.26},
  volume       = {390},
  year         = {2014},
}