Prograde amphibolite facies to ultrahigh-pressure transition along Nordfjord, western Norway: Implications for exhumation tectonics

The Nordfjord area of western Norway hosts one of the best known provinces of ultrahigh‐pressure (UHP) rocks in the world, yet the nature of the transition from the UHP rocks into surrounding amphibolite‐facies crust has remained unclear. New thermobarometry of phengite‐ and kyanite‐bearing eclogite...

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Bibliographic Details
Published in:Tectonics (Washington, D.C.) D.C.), 2007-02, Vol.26 (1), p.TC1007-n/a
Main Authors: Young, David J., Hacker, Bradley R., Andersen, Torgeir B., Corfu, Fernando
Format: Article
Language:English
Subjects:
eclogite thermobarometry
General or miscellaneous
Geochronology
Mineralogy and Petrology
single grain zircon geochronology
Thermobarometry
Ultra-high pressure metamorphism
ultrahigh-pressure metamorphism
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Summary:The Nordfjord area of western Norway hosts one of the best known provinces of ultrahigh‐pressure (UHP) rocks in the world, yet the nature of the transition from the UHP rocks into surrounding amphibolite‐facies crust has remained unclear. New thermobarometry of phengite‐ and kyanite‐bearing eclogites shows that this transition is unbroken by major structures: the pressure and temperature gradient increases smoothly over a horizontal distance of ∼20 km, from high‐pressure amphibolite facies (∼1.5 GPa/600–700°C) through quartz eclogite (∼2.4 GPa/600°C) into UHP eclogite (>2.7 GPa/700°C). These data support a model in which the Norwegian UHP province remained attached to lower pressure crust during exhumation. This requires that a large area of the Western Gneiss Region was metamorphosed and exhumed ∼60 km through the mantle, as a relatively coherent body.
ISSN:0278-7407
1944-9194
DOI:10.1029/2004TC001781