Thermobarometry and Geotectonic Significance of High-Pressure Granulites: Examples from the Moldanubian Zone of the Bohemian Massif in Lower Austria

Silurian high-pressure granulites from Central Qiangtang, Tibet: Constraints on early Paleozoic collision along the northeastern margin of Gondwana

“…5e). This result suggests that clinopyroxene from the peak metamorphic assemblage (M 1 ) was more aluminous, as expected for highpressure/high-temperature conditions (Anovitz, 1991;Carswell and O'Brien, 1993;Cooke, 2000). The considerable drop in Al 2 O 3 content from clinopyroxene inclusions in garnet to matrix clinopyroxene (Fig.…”

“…Locally, these symplectites completely replace garnet grains and occur as pseudomorphs after garnets. These symplectic or coronitic textures have been observed in many granulite terranes and are generally regarded to indicate that the rock experienced near-isothermal decompression after peak metamorphism (Guo et al, 2002;Harley, 1989Harley, , 1992Thost et al, 1991;Kumar and Chacko, 1994;Carswell and O'Brien, 1993;O'Brien and Rötzler, 2003;Zhao et al, 2001). Rarely, garnet is also surrounded by orthopyroxene (opx S ) + plagioclase (pl S1 ) + amphibole (amp S1 ) (Fig.…”

“…Apparently, the assemblage garnet + clinopyroxene + plagioclase + quartz dominated the rocks in the peak metamorphic episode. This is a characteristic HP granulite mineral assemblage (Harley, 1989;Carswell and O'Brien, 1993; O'Brien and Rötzler, 2003).…”

Determination of SiO2 Raman spectrum indicating the transformation from coesite to quartz in Gföhl migmatitic gneisses in the Moldanubian Zone, Czech Republic

“…Eclogites in the Gföhl Unit are associated with the peridotite bodies, except for one locality near Spačice (Medaris et al, 1998). Previous studies show that the Gföhl granulites have experienced a clockwise P -T path with peak conditions of approximately 1.6 -2.0 GPa and 900 -1100 °C, followed by nearly isothermal decompression to medium -P and high -T conditions (0.6 -0.8 GPa, 700 -800 °C) (Vrána, 1989;Carswell and O'Brien, 1993;Cooke, 2000;Cooke and O'Brien, 2001). In contrast, thermodynamic modeling by Štípská and Powell (2005) has yielded a metamorphic peak temperature of 750 -850 °C at 1.6 -1.8 GPa that is distinctly lower than that mentioned in previous studies.…”

“…The Gföhl Unit is mainly composed of the garnet -, kyanite -, and biotite -bearing felsic granulite (upper) units along with minor amounts of pyroxene -bearing granulite and the lower migmatitic gneiss unit (e.g., Carswell and O'Brien, 1993). Peridotite bodies sporadically occur both in the Gföhl granulite and Gföhl migmatitic gneiss.…”