Eo‐Variscan metamorphism in the bohemian massif: thermodynamic modeling and monazite geochronology of gneisses and granulites of the góry Sowie massif, SW poland

2021 ◽  
Author(s):  
Mirosław Jastrzębski ◽  
Bartosz Budzyń ◽  
Andrzej Żelaźniewicz ◽  
Patrik Konečný ◽  
Jiří Sláma ◽  
...  
Keyword(s):  
Thermodynamic Modeling ◽  
Bohemian Massif ◽  
Sw Poland ◽  
Variscan Metamorphism

scholarly journals Metasomatic effects in the lithospheric mantle beneath the NE Bohemian Massif: A case study of Lutynia (SW Poland) peridotite xenoliths

Lithos ◽  
2010 ◽  
Vol 117 (1-4) ◽  
pp. 49-60 ◽  
Author(s):  
Magdalena Matusiak-Małek ◽  
Jacek Puziewicz ◽  
Theodoros Ntaflos ◽  
Michel Grégoire ◽  
Hilary Downes
Keyword(s):  
Bohemian Massif ◽  
Lithospheric Mantle ◽  
Peridotite Xenoliths ◽  
Sw Poland

scholarly journals New K-Ar Cooling Ages of Granitoids from the Strzegom-Sobótka Massif, SW Poland

2007 ◽  
Vol 27 (-1) ◽  
pp. 5-9 ◽  
Author(s):  
Krzysztof Turniak ◽  
Stanislaw Halas ◽  
Artur Wójtowicz
Keyword(s):  
Bohemian Massif ◽  
Metamorphic Rocks ◽  
Low Grade ◽  
Age Group ◽  
Cooling History ◽  
Zircon Crystallization ◽  
Variscan Granitoids ◽  
History Of ◽  
Sw Poland ◽  
Maximum Estimate

New K-Ar Cooling Ages of Granitoids from the Strzegom-Sobótka Massif, SW Poland The Strzegom-Sobótka Variscan Massif (Fore-Sudetic Block, NE Bohemian Massif) consists of various post-kinematic Variscan granitoids emplaced into Palaeozoic low grade metamorphic rocks. Biotite from five samples representing the hornblende-biotite monzogranite, biotite monzogranite and biotite granodiorite has been dated using the K-Ar method for two size-fractions (0.25-0.35 and 0.35-0.5 mm). Finer fractions show more intense chloritization and therefore the results for them were rejected in further discussion. Coarser fractions with higher potassium content were accepted as yielding a maximum estimate approaching the true K-Ar biotite cooling ages. The results are clustered in two groups. The older age group (308.8±4.6 Ma and 305.5±4.3 Ma) comprises results obtained from the biotite granodiorites. They are generally consistent with the zircon crystallization age of 308.4±1.7 Ma reported by Turniak et al. (2005) and imply rapid cooling of the biotite granodiorite from magmatic temperatures down to the closure temperature of K-Ar isotopic system in biotite. The younger group is defined by 291.0±4.4 Ma and 298.7±5.2 Ma ages for the hornblende-biotite monzogranite and 294.2±4.3 Ma age for the biotite monzogranite. In the absence of precise U-Pb or Pb-Pb zircon data further geochronological studies are needed to decipher precisely the cooling history of the monzogranites.

Cambro-Ordovician vs Devono-Carboniferous geodynamic evolution of the Bohemian Massif: evidence from P–T–t studies in the Orlica–Śnieżnik Dome, SW Poland

2017 ◽  
Vol 156 (3) ◽  
pp. 447-470 ◽  
Author(s):  
MIROSŁAW JASTRZĘBSKI ◽  
BARTOSZ BUDZYŃ ◽  
WOJCIECH STAWIKOWSKI
Keyword(s):  
Bohemian Massif ◽  
Large Scale ◽  
Regional Metamorphism ◽  
Contact Metamorphism ◽  
Temperature Deformation ◽  
Geodynamic Evolution ◽  
Sw Poland ◽  
Break Up ◽  
Maximum Temperatures ◽  
Early Palaeozoic

AbstractThe pressure–temperature–deformation–time (P–T–d–t) record of metagranitic rocks and adjacent diverse rocks of the metavolcano-sedimentary group from the Orlica–Śnieżnik Dome (OSD) in SW Poland is examined. The study aims to better understand the course of the break-up of northern Gondwana and the overprinting Variscan tectonometamorphism in the NE Bohemian Massif. We test the existing hypotheses that explain the Cambro-Ordovician thermal event recorded in the meta-supracrustal group by (i) syn-deformational regional metamorphism or (ii) the contact metamorphism of the (meta)sedimentary rocks around the intruding ~490–500 Ma granitic magmas. In addition, we check the extent and timing of the Variscan prograde and retrograde medium-pressure metamorphism in the OSD. The results imply that Early Palaeozoic monazites, rarely preserved in both rock groups, document ~490–500 Ma volcanic and plutonic events related to the Gondwana's break-up and following disturbance of the Th–U–Pb system during younger, Variscan events. The monazite geochronology reveals no distinct Cambro-Ordovician thermal aureole around the post-granitic orthogneisses. However, no large-scale Variscan juxtaposition is evident between the two main OSD rock groups or within the meta-supracrustal rocks. Consistent P–T–d–t results for the meta-supracrustal rocks and the orthogneisses suggest that their precursors contacted before the Variscan tectonometamorphism. The directly contiguous ortho- and paragneisses together experienced tectonometamorphic processes at maximum depths that correspond to 7.5–8.0 kbar and maximum temperatures of ~600–620°C, as a result of the Variscan collision of Gondwana and Euramerica. The continental collision-related events intensified at ~360 Ma and ~330–340 Ma.

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