A gabbro to eclogite transition on Flemsøy, Sunnmøre, western Norway

Late Neoproterozoic granulite facies metamorphism in the Menderes Massif, Western Anatolia/Turkey: implication for the assembly of Gondwana

“…However, the origin of such coronitic microstructures between olivine-plagioclase described commonly in basic rocks is still controversial (De Haas et al, 2002 and references therein). This type of corona texture has been documented in high-P terranes (Indares, 1993;Indares & Rivers, 1995;Mørk, 1985;Mørk & Mearns, 1986) as a medium stage of gabbro-eclogite transformation and in medium-to highpressure amphibolite-to granulite-facies rocks (Grant, 1988;McLelland & Whitney, 1977;Whitney & McLelland, 1973). Furthermore, they can be observed even in non-metamorphic gabbros as reactions during magmatic cooling (Joesten, 1986;Turner & Stuewe, 1992).…”

Interplay between deformation and metamorphism during eclogitization of amphibolites in the Sesia–Lanzo Zone of the Western Alps

“…The catalysing effect of strain rate on metamorphic recrystallization has been considered, so far, by different authors on a single bulk composition (Mørk 1985;Pognante 1985;Koons 1986;Austrheim 1990;Rubie 1990;Messiga et al 1995;Spalla et al 1999;Hobbs et al in press). Our observations suggest that strain localization, manifest by the mesoscopic fabric gradient, is the additional variable triggering the recrystallization from coronitic eclogitized amphibolites to amphibole-bearing eclogite (Amp-in) and finally to eclogite (Amp-out).…”

“…Amphibolitic rocks of different bulk compositions involved in the Alpine cycle offer the opportunity to differentiate parameters influencing reaction progress along strain gradients and consequently the extent of metamorphic recrystallization during eclogitization. Fabric heterogeneity imposed by strain gradients preserved relics in partially eclogitized rocks with coronitic textures (low-or no-strain domains that escaped major deformation), adjacent to more re-equilibrated tectonitic (foliated) and mylonitic rocks (Mørk 1985;Pognante 1985;Austrheim 1990;Rubie 1990;Hobbs et al 2010). This fabric versus reaction interaction has been considered as the discriminating factor of transformation heterogeneity in gabbro-to-eclogite (oceanic crust) and granulite-to-eclogite (continental crust) transitions Messiga et al 1995).…”

Diffusion versus recrystallization processes in Rb–Sr geochronology: Isotopic relics in eclogite facies rocks, Western Gneiss Region, Norway

“…2), is controlled by the local environment, namely by local grain boundary geometries and the immediarely neighbouring granulitic phases.,This local control on metamorphic reaction products is incompatible with presence of free fluids during reaction, which would have enabled rapid transport of reaction components along grain boundaries thus eliminating the close geometric correlation between reactant phases and reaction products. We therefore take the local peculiarity of reaction products as a strong indication for diffusion-driven solid state reactions (Mørk, 1985;Gilotti and Elvevold, 1998), either without or with only very limited participation of fluids. The local control on reaction rim microtextures further corroborates a conclusion by Joesten (1991) that rapid diffusion along grain boundaries is not the dominant mechanism of mass transport during metamorphism.…”