Prograde amphibolite facies to ultrahigh-pressure transition along Nordfjord, western Norway: Implications for exhumation tectonics
نویسندگان
چکیده
[1] 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 phengiteand 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. Citation: Young, D. J., B. R. Hacker, T. B. Andersen, and F. Corfu (2007), Prograde amphibolite facies to ultrahigh-pressure transition along Nordfjord, western Norway: Implications for exhumation tectonics, Tectonics, 26, TC1007, doi:10.1029/2004TC001781.
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