Low-pressure Granulites of the Lišov Massif, Southern Bohemia: Viséan Metamorphism of Late Devonian Plutonic Arc Rocks

Janoušek, Vojtěch; Gerdes, Axel; Vrána, Stanislav; Finger, Friedrich; Erban, Vojtěch; Friedl, Gertrude; Braithwaite, C. J. R.

doi:10.1093/petrology/egi091

Cited by 100 publications

(57 citation statements)

References 99 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The apatite saturation temperatures obtained for the Grt-bearing hyperpotassic granulites (c. 1050 °C) are relatively constant and close to the previous peak tem- 'Brien and Rötzler 2003;Janoušek et al 2006b for reviews). On this basis they can be taken as reasonable estimates of the magma's liquidus temperature.…”

Section: Significance Of the Zircon Apatite And Monazite Saturation supporting

confidence: 80%

“…The regional differences in Rb/Sr ratios of this pre-Variscan protolith and consequently variable in situ growth of the radiogenic Sr with time could account for the dichotomy in the 87 Sr/ 86 Sr ratios. (Liew et al 1989;Vellmer and Wedepohl 1994;Gerdes 1997;Janoušek et al 2002), granitoids of the Central Bohemian Plutonic Complex (CBPC: Janoušek et al 1995;Sokol et al, 2000), durbachitic rocks (Holub and Janoušek 2003), Moldanubian metasediments (Janoušek et al 1995 and unpublished data) as well as Moldanubian calc-alkaline granulites (Vellmer 1992;Valbracht et al 1994;Becker et al 1999;Janoušek et al 2004;2006b). b) Detail of an analogous plot involving solely the granulites from the Blanský les granulite Massif both calcalkaline (Valbracht et al 1994;Janoušek et al 2004) and hyperpotassic (this work).…”

Section: Relationship Between the Two Types Of The Hyperpotassic Granmentioning

confidence: 99%

See 1 more Smart Citation

Hyperpotassic granulites from Blanský les (Moldanubian Zone, Bohemian Massif) revisited

Janoušek¹,

Krenn²,

Finger³

et al. 2012

J. Geosci.

View full text Add to dashboard Cite

In the Blanský les granulite Massif (Moldanubian Unit, South Bohemia), built mainly by felsic calc-alkaline HP-HT garnet ± kyanite granulite, occur rare small bodies of hyperpotassic granulite with garnet (Plešovice type) or pyroxene (Lhotka type). The Plešovice type is dominated by slightly perthitic K-feldspar and almandine-pyrope rich garnet, the latter variously retrogressed to biotite ± plagioclase. The other conspicuous euhedral crystals are apatite and zircon. In the rock occur also Zr-Nb-rich rutile and much rarer primary monazite; originally LREE-rich apatites decompose into small Th-poor, MREE-rich monazite grains. The Lhotka type granulites contain pyroxene, often altered to actinolite, instead of garnet. The predominant perthitic K-feldspar encloses a small amount of unmixed celsian. Typical are large euhedral crystals of apatite with small unmixed monazite grains; primary monazite is rare. Noteworthy is the occurrence of secondary Ti phases with high REE, Y and Zr, formed at the expense of the primary pyroxene. The studied granulite types are highly potassic (K 2 O > 7 %, up to c. 14 %, K 2 O/Na 2 O = 3.1-9.2 wt. %), silica-poor (SiO 2 < 65 %), with low contents of most major-and minor-element oxides, apart from K and P. Characteristic are high concentrations of Cs, Rb, Ba and U at variable enrichments in Zr and Hf. Whole-rock contents some HFSE (Ti, Nb and Ta) are extremely low. The REE patterns show marked negative Eu anomalies and variable LREE enrichments increasing with rising silica due to a conspicuous drop in HREE. The Sr-Nd isotopic ratios document the derivation Sr/ 86 Sr 337 = 0.7109 for the Lhotka types). Apatite saturation temperatures are high (~1070 °C), close to the previously estimated conditions of (re)crystallization for both calc-alkaline and hyperpotassic granulites. The zircon saturation temperatures tend to be more variable, some exceeding 1000 °C but many unrealistically low, reflecting effects of disequilibrium melting, heterogeneous distribution of accumulated crystals in the magma and/or sampling bias. The hyperpotassic granulites are interpreted as Viséan igneous rocks. The parental magma could have originated by low degrees of HP-HT, non-eutectic partial melting. The low-scale melt was most likely expelled close to the HP-HT metamorphic peak or at early stages of decompression from common Moldanubian calc-alkaline granulites. This genetic link is documented by the presumed P-T conditions, similar age and complementary geochemical and Sr-Nd isotopic signatures. Subsequently the magma could have developed by garnet, apatite and zircon dominated fractional crystallization, with or without some crystal accumulation.

show abstract

Section: Significance Of the Zircon Apatite And Monazite Saturation supporting

confidence: 80%

Section: Relationship Between the Two Types Of The Hyperpotassic Granmentioning

confidence: 99%

Hyperpotassic granulites from Blanský les (Moldanubian Zone, Bohemian Massif) revisited

Janoušek¹,

Krenn²,

Finger³

et al. 2012

J. Geosci.

View full text Add to dashboard Cite

show abstract

“…Supplementary data Supplementary Frei and Gerdes, 2009;Gerdes and Zeh, 2009;Jackson et al, 2004;Janousek et al, 2006; data associated with this article can be found , in the online version, at doi:l 0.1 016/j.precamres.201 0.05.018 .…”

Section: Acknowledgmentsmentioning

confidence: 99%

Detrital zircon ages of Neoproterozoic sequences of the Moroccan Anti-Atlas belt

Abati

Aghzer

Gerdes

et al. 2010

Precambrian Research

Self Cite

149

View full text Add to dashboard Cite

“…Numerous geochronological studies from the south Bohemian granulites indicate metamorphic ages of c. 340 Ma, along with a few exceptions of older ages (e.g. van Breemen et al 1982;Wendt et al 1994;Kröner et al 2000;Svojtka et al 2002;Janoušek et al 2006).…”

Section: For a Review)mentioning

confidence: 99%

Geophysical and structural pattern of the Knížecí Stolec pluton and its host rocks in the south-western part of the Moldanubian Zone, Bohemian Massif

Sedlák¹,

Gnojek²,

Verner³

et al. 2012

J. Geosci.

View full text Add to dashboard Cite

A detailed airborne magnetic and gamma-ray spectrometric as well as ground gravity survey in the south-western part of the Moldanubian Zone (Bohemian Massif) provided detailed geophysical characteristics of the principal geological units and large-scale tectonic features. The Knížecí Stolec durbachitic pluton with high contents of natural radioactive elements (Th, U and K) represents a body with no magnetically anomalous response but a pronounced positive gravity anomaly. The Křišťanov granulite massif, which is a host rock of the Knížecí Stolec pluton, exhibits low concentrations of Th and U, high abundances of K, slight magnetic and a negative gravity anomalies. The Plechý composite pluton is characterized by strikingly low gravity and an extremely monotonous magnetic field. One of its petrographic varieties (the Třístoličník granite) is enriched in natural radioactive elements, especially in Th and U. Metamorphic complexes of the Monotonous and Varied groups contain multiple magnetic anomalies mostly related to the intercalated metabasic rocks; they also cause positive gravity anomalies. The Linsser density boundaries at a depth of 0.5 km clearly delimit the Plechý composite pluton and the Lhenice zone and indicate several structurally and/or lithologically different domains within the Křišťanov granulite massif and in the Knížecí Stolec pluton. The 2.5D gravity model indicates an asymmetric shape of the Knížecí Stolec pluton, which is deepest in its SE part (at least 4 km). The joint interpretation of the geophysical and structural data revealed that the maximum depth of the pluton is c. 4.5 km, with gently to moderately dipping intrusive contacts in the north and subvertical orientation in the south. The asymmetric shape of the pluton is consistent with its inferred syn-tectonic emplacement coeval with the regional subvertical contraction and development of regional flat-lying fabric. The gravity model combined with structural analyses also implies a considerable depth of the south Bohemian granulite massifs. This indicates their steep exhumation path and is at variance with the model of the Moldanubian Zone as a sequence of flat-lying nappes. The south-western part of the studied area is reworked by the NE-directed compression, referred to as the ‛Bavarian' deformation phase.

show abstract

Low-pressure Granulites of the Lišov Massif, Southern Bohemia: Viséan Metamorphism of Late Devonian Plutonic Arc Rocks

Cited by 100 publications

References 99 publications

Hyperpotassic granulites from Blanský les (Moldanubian Zone, Bohemian Massif) revisited

Hyperpotassic granulites from Blanský les (Moldanubian Zone, Bohemian Massif) revisited

Detrital zircon ages of Neoproterozoic sequences of the Moroccan Anti-Atlas belt

Geophysical and structural pattern of the Knížecí Stolec pluton and its host rocks in the south-western part of the Moldanubian Zone, Bohemian Massif

Contact Info

Product

Resources

About