Isothermal compression of an eclogite from the Western Gneiss Region (Norway)
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F23%3A10168326" target="_blank" >RIV/00025798:_____/23:10168326 - isvavai.cz</a>
Result on the web
<a href="https://onlinelibrary.wiley.com/doi/10.1111/jmg.12692" target="_blank" >https://onlinelibrary.wiley.com/doi/10.1111/jmg.12692</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1111/jmg.12692" target="_blank" >10.1111/jmg.12692</a>
Alternative languages
Result language
angličtina
Original language name
Isothermal compression of an eclogite from the Western Gneiss Region (Norway)
Original language description
In the Western Gneiss Region in Norway, mafic eclogites form lenses within granitoid orthogneiss and contain the best record of the pressure and temperature evolution of this ultrahigh-pressure (UHP) terrane. Their exhumation from the UHP conditions has been extensively studied, but their prograde evolution has been rarely quantified although it represents a key constraint for the tectonic history of this area. This study focused on a well-preserved phengite-bearing eclogite sample from the Nordfjord region. The sample was investigated using phase-equilibrium modelling, trace-element analyses of garnet, trace- and major-element thermobarometry and quartz-in-garnet barometry by Raman spectroscopy. Inclusions in garnet core point to crystallization conditions in the amphibolite facies at 510-600oC and 11-16 kbar, whereas chemical zoning in garnet suggests growth during isothermal compression up to the peak pressure of 28 kbar at 600oC, followed by near-isobaric heating to 660-680oC. Near-isothermal decompression to 10-14 kbar is recorded in fine-grained clinopyroxene-amphibole-plagioclase symplectites. The absence of a temperature increase during compression seems incompatible with the classic view of crystallization along a geothermal gradient in a subduction zone and may question the tectonic significance of eclogite facies metamorphism. Two end-member tectonic scenarios are proposed to explain such an isothermal compression: Either (1) the mafic rocks were originally at depth within the lower crust and were consecutively buried along the isothermal portion of the subducting slab or (2) the mafic rocks recorded up to 14 kbar of tectonic overpressure at constant depth and temperature during the collisional stage of the orogeny.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10505 - Geology
Result continuities
Project
—
Continuities
V - Vyzkumna aktivita podporovana z jinych verejnych zdroju
Others
Publication year
2023
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Journal of Metamorphic Geology
ISSN
0263-4929
e-ISSN
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Volume of the periodical
41
Issue of the periodical within the volume
January
Country of publishing house
GB - UNITED KINGDOM
Number of pages
23
Pages from-to
181-203
UT code for WoS article
000863604600001
EID of the result in the Scopus database
2-s2.0-85139111465