Metamorphic Evolution

Vrána, Stanislav; Blümel, Peter; Petrakakis, Konstantin

doi:10.1007/978-3-642-77518-5_45

Cited by 19 publications

(11 citation statements)

References 16 publications

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“…The Moldanubian batholith (also referred to as the Moldanubian Plutonic Complex, South Bohemian Batholith, or South Bohemian Pluton), with an over *6,000-10,000 km 2 exposed area of plutonic rocks, is one of the largest Gerdes et al (2000) and Holub et al (1995) plutonic bodies in the Variscan orogenic belt in Europe. The host rocks are chiefly paragneisses, migmatized paragneisses, and migmatites (the Monotonous Group; Vrána 1988;Vrána et al 1995).…”

Section: Geological Settingmentioning

confidence: 99%

“…(2) Rapid exhumation of the lower-to middle-crust at around *340 Ma (e.g., Willner et al 2002 and references therein) is associated with the intrusion of ultrapotassic, magnesium-rich plutons (e.g., Holub 1997;Janoušek and Holub 2007;Verner et al 2006Verner et al , 2007. (3) During and after the subsequent LP-HT regional metamorphism and anatexis in the innermost part of the orogenic belt (variously referred to as the Moldanubian Unit, Moldanubian Zone, or Moldanubicum) dated at *337-321 Ma (e.g., Kalt et al 1999Kalt et al , 2000Tropper et al 2006;Vrána et al 1995;Willner et al 2002), the Moldanubian Unit was intruded by large volumes of peraluminous, S-type and high-K I-type granitoids. (4) Late Variscan strike-slip shearing (Brandmayr et al 1995;Edel et al 2003) broadly overlaps the emplacement of calcalkaline, I-type plutons (as young as 310-290 Ma), which terminate the main magmatic activity.…”

Section: Introductionmentioning

confidence: 99%

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Magmatic history and geophysical signature of a post-collisional intrusive center emplaced near a crustal-scale shear zone: the Plechý granite pluton (Moldanubian batholith, Bohemian Massif)

Verner

Žák

Pertoldová

et al. 2007

Int J Earth Sci (Geol Rundsch)

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The Plechý pluton, southwestern Bohemian Massif, represents a late-Variscan, complexly zoned intrusive center emplaced near the crustal-scale Pfahl shear zone; the pluton thus provides an opportunity to examine the interplay among successive emplacement of large magma batches, magmatic fabric acquisition, and the late-Variscan stress field associated with strike-slip shearing. The magmatic history of the pluton started with the emplacement of the porphyritic Plechý and Haidmühler granites. Based on gravity and structural data, we interpret that the Plechý and Haidmühler granites were emplaced as a deeply rooted, *NE-SW elongated body; its gross shape and internal fabric (steep *NE-SW magmatic foliation) may have been controlled by the late-Variscan stress field. The steep magmatic foliation changes into flat-lying foliation (particularly recorded by AMS) presumably as a result of divergent flow. Magnetic lineations correspond to a sub-horizontal *NE-SW finite stretch associated with the divergent flow. Subsequently, the Třístoličník granite, characterized by steep margin-parallel magmatic foliation, was emplaced as a crescent-shaped body in the central part of the pluton. The otherwise inward-younging intrusive sequence was completed by the emplacement of the outermost and the most evolved garnet-bearing granite (the Marginal granite) along the southeastern margin of the pluton.

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Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magmatic history and geophysical signature of a post-collisional intrusive center emplaced near a crustal-scale shear zone: the Plechý granite pluton (Moldanubian batholith, Bohemian Massif)

Verner

Žák

Pertoldová

et al. 2007

Int J Earth Sci (Geol Rundsch)

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“…The Moldanubian Zone is interpreted as a root zone of the Variscan belt, resulting from collision of Gondwana with Laurasia (e.g., Schulmann et al 2009). Metamorphic rocks of the Moldanubian Zone include mainly amphibolite-facies gneisses and migmatites with early Palaeozoic and late Proterozoic protolith ages (Košler et al 2013), as well as highpressure granulites, often with lenses or larger bodies of garnet and spinel peridotites and eclogites (Vrána et al 1995). Subdivision of the Moldanubian Zone was presented in Dallmeyer et al (1995) and McCann (2008); stratigraphy and lithology were characterized by Fiala et al (1995).…”

Section: Moldanubian Zone Of the Bohemian Massifmentioning

confidence: 99%

Petrology and geochemical characteristics of phlogopite pyroxenite related to durbachites, Moldanubian Zone, Bohemian Massif

Trubač¹,

Vrána²,

Haluzová³

et al. 2015

J. Geosci.

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The phlogopite pyroxenite with a high content of pyrrhotite forms a body of circular outline about 1 km in diameter at Přední Zvonková in Moldanubian Zone (Šumava/Bohemian Forest/Böhmerwald), Czech Republic. The contours of pyroxenite body are indicated by magnetometry and gravity data. Loose blocks up to 70 cm in size scattered on fields in the flat terrain indicate that the rock is at least partly exposed at the current erosion level. The best preserved sample SV235A is a medium-grained rock containing 27 vol. % phlogopite, 23 % diopside, 25 % enstatite, abundant apatite (7 %), minor plagioclase (3 %, An 39-42 ), and pyrrhotite (3 %). Tendency to sulphide segregation is indicated by several mm pyrrhotite aggregates enclosing individual grains of pyroxenes, phlogopite and apatite. In the mg# vs. MgO diagram the studied pyroxenites plot along the linear trend defined by granitoid durbachites (melanocratic quartz syenites, quartz monzodiorites to melagranites), biotite-amphibole quartz diorites and biotite-amphibole ultramafic rocks (all from the Moldanubian Zone in southern and south-central Bohemia), after the whole-rock compositions of pyroxenites are corrected for the respective content of pyrrhotite. Several pyroxene thermometers yield equilibration temperatures in the range of 970 to 1040 °C for the sample SV235A. The Re-Os and Sr-Nd isotope composition of whole-rock samples indicates important crustal component in the sulphides and silicates. Petrological and geochemical data show a major role of fractional crystallization/crystal accumulation in formation of these rocks but magma mixing process is also recorded. The phlogopite pyroxenite is a rare rock important for understanding genesis of durbachitic magmatism. Received: 15 January 2015; accepted: 18 March 2015; handling editor: Emil Jelínek similarities and genetic affinity to durbachites. Whereas in the published papers on durbachites discussion of melt origins and magma mixing prevailed, the newly obtained data on phlogopite pyroxenite indicate a role of fractional crystallization in evolution of durbachitic magmas. Breiter (2008) The existence of relatively abundant fine-grained enclaves in durbachites, having a more mafic composition (Holub 1997), amphibole-phlogopite ultramafic rocks and amphibole-phlogopite quartz diorites intruded mainly in the Prachatice Granulite Massif (Hejtman 1975;Breiter and Koller 2009) represent additional reasons to discuss possible role of fractional crystallization in evolution of durbachitic magmas. We will show that comparison of new data on phlogopite pyroxenite with published ones on durbachitic rocks presents evidence that both the processes were important in generation of the phlogopite pyroxenite. Keywords: phlogopite pyroxenite, durbachite, cumulate, Moldanubian Zone

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“…1, 2). The high-grade Moldanubian rocks are characterized by strong Variscan polyphase metamorphism and complex deformational history (see Vra´na 1988;Vra´na et al 1995 for reviews). The HP-HT metamorphic event in the Moldanubian Unit is recorded in granulites and rarely also in pelitic lithologies; most U-Pb zircon and monazite ages fall into the range 355-337 Ma (Friedl et al 1993;Janousˇek et al 2004bJanousˇek et al , 2006 and references therein; Kro¨ner et al 1988Kro¨ner et al , 2000Wendt et al 1994) and were followed by LP-HT metamorphism and migmatization at $337-333 Ma (Friedl et al 1993(Friedl et al , 1994Gerdes et al 2000 and references therein).…”

Section: Moldanubian Unitmentioning

confidence: 99%

Magmatic stoping as an important emplacement mechanism of Variscan plutons: evidence from roof pendants in the Central Bohemian Plutonic Complex (Bohemian Massif)

Žák

Holub

Kachlík

2006

Int J Earth Sci (Geol Rundsch)

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The presence of numerous roof pendants, stoped blocks and discordant intrusive contacts suggests that magmatic stoping was a widespread, large-scale process during the final construction of the Central Bohemian Plutonic Complex, Bohemian Massif. The measured total length of the discordant contacts that cut off the regional cleavage and were presumably formed by stoping corresponds to about half of all contacts with the upper-crustal host rocks. In addition, at least some of the straight, cleavage-parallel intrusive contacts may also have recorded complex intrusive histories ending with piecemeal stoping of thin cleavage-bounded host rock blocks into the magma chamber. Based on the above, we argue that the fast strain rates required for emplacement of large plutons of the Central Bohemian Plutonic Complex into brittle upper crustal host rocks over relatively short-time span could not have been accommodated entirely by slow ductile flow or slip along faults. Instead, the emplacement was largely accommodated by much faster thermal cracking and extensive stoping independent of regional tectonic deformation. Finally, we emphasize that magmatic stoping may significantly modify the preserved structural patterns around plutons, may operate as an important mechanism of final construction of upper-crustal plutons and thus may contribute to vertical recycling and downward transport of crustal material within the magma plumbing systems in the crust.

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Metamorphic Evolution

Cited by 19 publications

References 16 publications

Magmatic history and geophysical signature of a post-collisional intrusive center emplaced near a crustal-scale shear zone: the Plechý granite pluton (Moldanubian batholith, Bohemian Massif)

Magmatic history and geophysical signature of a post-collisional intrusive center emplaced near a crustal-scale shear zone: the Plechý granite pluton (Moldanubian batholith, Bohemian Massif)

Petrology and geochemical characteristics of phlogopite pyroxenite related to durbachites, Moldanubian Zone, Bohemian Massif

Magmatic stoping as an important emplacement mechanism of Variscan plutons: evidence from roof pendants in the Central Bohemian Plutonic Complex (Bohemian Massif)

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