Western Gneiss Complex, Norway, and implications

pressure (UHP) eclogite bodies enclosed in predominantly felsic amphibolite-facies rocks. The Drbsdal body, located in the Sunnfjord area, is one of the largest and best-preserved eclogites in the WGC, and comprises over ca. 3 km2 of exposed extensional exhumation. Our observations are consistent with models involving inhomogeneous deformation of the lower crust Tectonophysics xx (2005) xxx–xxx www.elsevier.com/locate/tecto DTD 5eclogite-facies rocks. It is an excellent example of an eclogite tectonite, and displays a wealth of structures formed during deformation at a minimum depth of 50 km and peak temperatures of ca. 800 8C. Large volumes of mylonites with the eclogite-facies assemblage garnetFclinopyroxeneFquartzFamphiboleFclinozoisiteFphengiteFkyaniteFrutile are preserved. Struc-tures associated with the eclogite-facies metamorphism include E–W-trending isoclinal folds, boudinage, hinge-parallel lineations, and meter-scale kyanite-dominated veins. The Drbsdal body was tightly folded on the kilometer scale under eclogite-facies conditions. Subsequently, the shapes of the Drbsdal body and other mafic bodies in the Sunnfjord area were modified during eclogite-to-amphibolite-facies E–W-directed stretching, to give boudin-like lenses. The timing of formation of a pervasive eclogite-facies lineation, eclogite-facies folds, and kyanite bearing veins overlapped substantially, and this portion of the deformation history was dominated by a constrictional strain field. Partitioning of deformation occurred after a substantial amount of eclogite-facies deformation had already taken place, and resulted in the relative rotation of linear features in specific zones on the scale of ~400 m. The eclogite-facies lineations and fold hinges within the Drbsdal body are subparallel to amphibolite and greenschist-facies structures throughout the WGC. Although circumstantial, this suggests that structures belonging to each of these three metamorphic facies formed during one progressive deformation event corresponding toEclogite-facies polyphase deformation of the Drbsdal eclogite