Olivine-bearing symplectites in fractured garnet from eclogite, Moldanubian Zone (Bohemian Massif) - a short-lived, granulite facies event

2015 ◽  
Vol 33 (6) ◽  
pp. 597-612 ◽  
Author(s):  
S. W. Faryad ◽  
M. Fišera
Keyword(s):  
Bohemian Massif ◽  
Granulite Facies ◽  
Moldanubian Zone

Deciphering the petrogenesis of deeply buried granites: whole-rock geochemical constraints on the origin of largely undepleted felsic granulites from the Moldanubian Zone of the Bohemian Massif

2004 ◽  
Vol 95 (1-2) ◽  
pp. 141-159 ◽  
Author(s):  
Vojtěch Janoušek ◽  
Fritz Finger ◽  
Malcolm Roberts ◽  
Jiří Frýda ◽  
Christian Pin ◽  
...  
Keyword(s):  
Bohemian Massif ◽  
Granitic Rocks ◽  
Granitic Magma ◽  
Moldanubian Zone ◽  
Trace Element Contents ◽  
High Grade Metamorphism ◽  
Early Palaeozoic ◽  
High Level ◽  
Geochemical Constraints ◽  
Variation Trends

ABSTRACTThe prominent felsic granulites in the southern part of the Bohemian Massif (Gföhl Unit, Moldanubian Zone), with the Variscan (∼340 Ma) high-pressure and high-temperature assemblage garnet+quartz+hypersolvus feldspar ± kyanite, correspond geochemically to slightly peraluminous, fractionated granitic rocks. Compared to the average upper crust and most granites, the U, Th and Cs concentrations are strongly depleted, probably because of the fluid and/or slight melt loss during the high-grade metamorphism (900–1050°C, 1·5–2·0 GPa). However, the rest of the trace-element contents and variation trends, such as decreasing Sr, Ba, Eu, LREE and Zr with increasing SiO2 and Rb, can be explained by fractional crystallisation of a granitic magma. Low Zr and LREE contents yield ∼750°C zircon and monazite saturation temperatures and suggest relatively low-temperature crystallisation. The granulites contain radiogenic Sr (87Sr/86Sr340 = 0·7106–0·7706) and unradiogenic Nd ( = − 4·2 to − 7·5), indicating derivation from an old crustal source. The whole-rock Rb–Sr isotopic system preserves the memory of an earlier, probably Ordovician, isotopic equilibrium.Contrary to previous studies, the bulk of felsic Moldanubian granulites do not appear to represent separated, syn-metamorphic Variscan HP–HT melts. Instead, they are interpreted as metamorphosed (partly anatectic) equivalents of older, probably high-level granites subducted to continental roots during the Variscan collision. Protolith formation may have occurred within an Early Palaeozoic rift setting, which is documented throughout the Variscan Zone in Europe.

From orthogneiss to migmatite: Geochemical assessment of the melt infiltration model in the Gföhl Unit (Moldanubian Zone, Bohemian Massif)

Lithos ◽  
2008 ◽  
Vol 102 (3-4) ◽  
pp. 508-537 ◽  
Author(s):  
P. Hasalová ◽  
V. Janoušek ◽  
K. Schulmann ◽  
P. Štípská ◽  
V. Erban
Keyword(s):  
Bohemian Massif ◽  
Moldanubian Zone ◽  
Infiltration Model ◽  
Melt Infiltration ◽  
Geochemical Assessment
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