caa a22 4500 467890153 CHVBK 20180406152746.0 cr unu---uuuuu 170328e20060301xx s 000 0 eng 10.1007/s00710-005-0108-2 doi (NATIONALLICENCE)springer-10.1007/s00710-005-0108-2 O'Brien P. J. Institut für Geowissenschaften, Universität Potsdam, Potsdam, Germany aut Type-locality granulites: high-pressure rocks formed at eclogite-facies conditions [Elektronische Daten] [P. J. O'Brien] Summary: The type-locality granulites from the Granulitgebirge of Saxony, Germany, are rocks of broadly granitic composition containing minor garnet and kyanite within a commonly mylonitised matrix of feldspars and quartz. Petrographic evidence indicates a primary assemblage of ternary feldspar + quartz + garnet + kyanite + rutile, most likely resulting from partial melting of a granitic protolith, for which equilibrium temperature and pressure conditions of >1000 °C and >1.5 GPa have been deduced. These extreme (for crustal rocks) conditions, and the inferred peak assemblage, are supported by the newly-developed Zr-in-rutile geothermometer and experimental studies on the same bulk composition, respectively. As these conditions lie above those required for plagioclase stability in quartz tholeiites, they are thus in the eclogite facies. Widespread modification of the peak assemblage, for example mesoperthite formation after ternary feldspar, deformation-induced recrystallisation of perthites to two-feldspar + quartz aggregates, biotite replacing garnet, Ca-loss at garnet rims, sillimanite replacing kyanite or secondary garnet growth, makes reliable interpretation of equilibrium assemblages and compositions very difficult and explains the spread of published pressure-temperature values and consequent confusion about formation depths and the validity of tectonometamorphic models. Such extreme metamorphic conditions in rock compositions typical for the upper continental crust, reflecting a hot subduction environment, has important consequences for understanding some collisional orogens. Springer-Verlag/Wien, 2006 Mineralogy and Petrology Springer-Verlag 86/3-4(2006-03-01), 161-175 0930-0708 86:3-4<161 2006 86 710 https://doi.org/10.1007/s00710-005-0108-2 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00710-005-0108-2 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- O'Brien P. J. Institut für Geowissenschaften, Universität Potsdam, Potsdam, Germany aut NATIONALLICENCE 773 0- Mineralogy and Petrology Springer-Verlag 86/3-4(2006-03-01), 161-175 0930-0708 86:3-4<161 2006 86 710 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer