caa a22 4500 465791247 CHVBK 20180323112025.0 cr unu---uuuuu 170327e19900201xx s 000 0 eng 10.1007/BF00306442 doi (NATIONALLICENCE)springer-10.1007/BF00306442 Fluid controlled eclogitization of granulites in deep crustal shear zones, Bergen arcs, Western Norway [Elektronische Daten] [Bjørn Jamtveit, Kurt Bucher-Nurminen, Håkon Austrheim] During the Caledonian orogeny large parts of the western margin of the Baltic shield were disrupted, sliced and stacked. Caledonian deformation resulted in a massif thickening of the continental crust. Mafic granulites and granulite facies meta-anorthosites build up a large portion of the Bergen Arcs terrane in southwestern Norway. The rocks represent typical Precambrian continental lower crust. These rocks experienced extensive eclogitization in response to stacking and crustal thickening during the Caledonian orogenic cycle. Eclogite formation resulted from shear deformation and associated infiltration of H2O-rich fluids (X H2O≥0.75). During an early stage, eclogite facies mineralogy formed in extension fractures (veins). The veins are probably related to hydraulic fracture systems which transported the inferred fluid phase. During the main stage, eclogitization occurred along shear zones ranging from centimeters to tens of meters in thickness. Eclogite forming reactions are shown to consume H2O, alkalies and to release SiO2. Much of the SiO2 released by the eclogitization process can be found in late quartz vein systems. The eclogitization took place at a temperature of about 700°C and a pressure between 18 and 21 kbar. Fluid infiltration was supported by a decrease in rock volume during reaction (ΔV solids<0). The negative volume change of reaction occurs despite that the process of eclogitization involves hydration reactions. The formation of eclogite from granulite produces approximately 15 KJ heat per 100 cm3 original granulite. Numerical modeling of the regional temperature effects associated with partial hydration of the lower crust suggests that these processes may not cause large perturbations on the geotherm. Both, transport of heat and matter by advection of the fluid phase is negligible on a regional scale. Springer-Verlag, 1990 Jamtveit Bjørn Department of Geology, University of Oslo, Blindern, PB 1047, N-0316, Oslo 3, Norway aut Bucher-Nurminen Kurt Department of Geology, University of Oslo, Blindern, PB 1047, N-0316, Oslo 3, Norway aut Austrheim Håkon Mineralogical and Geological Museum, University of Oslo, Sarsgate 1, N-0562, Oslo 5, Norway aut Contributions to Mineralogy and Petrology Springer-Verlag 104/2(1990-02-01), 184-193 0010-7999 104:2<184 1990 104 410 https://doi.org/10.1007/BF00306442 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00306442 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Jamtveit Bjørn Department of Geology, University of Oslo, Blindern, PB 1047, N-0316, Oslo 3, Norway aut NATIONALLICENCE 700 1- Bucher-Nurminen Kurt Department of Geology, University of Oslo, Blindern, PB 1047, N-0316, Oslo 3, Norway aut NATIONALLICENCE 700 1- Austrheim Håkon Mineralogical and Geological Museum, University of Oslo, Sarsgate 1, N-0562, Oslo 5, Norway aut NATIONALLICENCE 773 0- Contributions to Mineralogy and Petrology Springer-Verlag 104/2(1990-02-01), 184-193 0010-7999 104:2<184 1990 104 410 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer