scholarly journals Allanite from Granitic Rocks of the Moldanubian Batholith (Central European Variscan Belt)

2020 ◽  
Author(s):  
Miloš René
Keyword(s):  
Granitic Rocks ◽  
Variscan Belt ◽  
Central European

scholarly journals Uraninite, Coffinite and Brannerite from Shear-Zone Hosted Uranium Deposits of the Bohemian Massif (Central European Variscan Belt)

Minerals ◽  
2017 ◽  
Vol 7 (4) ◽  
pp. 50 ◽  
Author(s):  
Miloš René ◽  
Zdeněk Dolníček
Keyword(s):  
Shear Zone ◽  
Bohemian Massif ◽  
Variscan Belt ◽  
Uranium Deposits ◽  
Massif Central ◽  
Central European

Age constraints for the thermal evolution and erosional history of the central European Variscan belt: new data from the sediments and basement of the Carboniferous foreland basin in western Poland

2006 ◽  
Vol 163 (6) ◽  
pp. 1011-1024 ◽  
Author(s):  
StanisŁaw Mazur ◽  
W.James Dunlap ◽  
Krzysztof Turniak ◽  
Teresa Oberc-Dziedzic
Keyword(s):  
Thermal Evolution ◽  
Foreland Basin ◽  
Variscan Belt ◽  
Central European ◽  
History Of ◽  
Age Constraints

Uplift and late orogenic deformation of the Central European Variscan belt as revealed by sediment provenance and structural record in the Carboniferous foreland basin of western Poland

2008 ◽  
Vol 99 (1) ◽  
pp. 47-64 ◽  
Author(s):  
S. Mazur ◽  
P. Aleksandrowski ◽  
K. Turniak ◽  
L. Krzemiński ◽  
K. Mastalerz ◽  
...  
Keyword(s):  
Foreland Basin ◽  
Sediment Provenance ◽  
Variscan Belt ◽  
Central European

scholarly journals Variscan intracrustal recycling by melting of Carboniferous arc-like igneous protoliths (Évora Massif, Iberian Variscan belt)

2021 ◽  
Author(s):  
Carmen Rodríguez ◽  
Manuel Francisco Pereira ◽  
Antonio Castro ◽  
Gabriel Gutiérrez-Alonso ◽  
Carlos Fernández
Keyword(s):  
Early Carboniferous ◽  
Granitic Rocks ◽  
Variscan Belt ◽  
Gneiss Dome ◽  
Magmatic Arc ◽  
Rheic Ocean ◽  
Ridge Subduction ◽  
The North ◽  
Magmatic Event ◽  
Igneous Protoliths

Bulk rock geochemistry and sensitive high-resolution ion microprobe zircon geochronology of igneous and metaigneous rocks of the Évora gneiss dome, located to the north of the reworked Rheic Ocean suture zone in the southwest Iberian Variscan belt, reveal a succession of magmatic and melting events lasting ∼30 m.y. between ca. 341−314 Ma. The study of detailed field relationships of orthomigmatites (i.e., migmatites from igneous protoliths) and host granitic rocks proved to be crucial to reconstruct the complex sequence of tectono-thermal events of the Évora gneiss dome. The older igneous protoliths, with marked geochemical arc-like signatures, are represented by 338 ± 3 Ma tonalites and 336 ± 3 Ma diorites. These tonalites and diorites appear as mesosomes of igneous orthomigmatites containing new melts (leucosomes) of monzogranite composition and silica-poor trondhjemites formed in a melting episode at 329 ± 4/6 to 327 ± 3 Ma. The absence of peritectic phases (e.g., pyroxene), together with shearing associated with migmatization, imply the existence of water-rich fluids during melting of the older igneous rocks of the Évora gneiss dome. This melting event is coeval with the second magmatic event of the Évora gneiss dome represented by the neighboring Pavia pluton. A porphyritic monzogranite dated at 314 ± 4 Ma defines a later magmatic event. The porphyritic monzogranite encloses large blocks of the orthomigmatites and contains magmatic mafic enclaves (autoliths) dated at 337 ± 4 Ma that are ∼23 m.y. older than the host rock. All studied rocks of the Évora gneiss dome show arc-like, calc-alkaline geochemical signatures. Our results support recycling of intermediate-mafic plutonic rocks, representing the root of an early magmatic arc that formed at the time of Gondwana-Laurussia convergence (after the closure of the Rheic Ocean) and coeval subduction of the Paleotethys. A geodynamic model involving ridge subduction is proposed to explain the Early Carboniferous intra-orogenic crustal extension, dome formation, exhumation of high-grade rocks, compositional variations of magmatism and formation of new granitic magmatism in which, arc-like signatures were inherited from the crustal source.

scholarly journals Alteration of Granitoids and Uranium Mineralization in the Blatná Suite of the Central Bohemian Plutonic Complex, Czech Republic

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 821
Author(s):  
Miloš René
Keyword(s):  
Czech Republic ◽  
Low Temperature ◽  
Shear Zones ◽  
Uranium Mineralization ◽  
Granitic Rocks ◽  
Uranium Deposits ◽  
Magmatic Complex ◽  
Central European ◽  
Plutonic Complex ◽  
European Variscides

The Bohemian magmatic complex belongs to granitoid plutons of the Central European Variscides. Hydrothermal uranium mineralization evolved in the small uranium deposits Nahošín and Mečichov is associated with N–S shear zones occurring on the SW margin of the Central Bohemian plutonic complex formed by amphibole-bearing biotite granodiorites of the Blatná suite. The purpose of presented study is description of uranium mineralization bounded on brittle shear zones, which is coupled with intense low-temperature hydrothermal alteration of granitic rocks. Uranium mineralization, formed predominantly of coffinite, rare uraninite, and thorite, is accompanied by intense hematitization, albitization, chloritization, and carbonatization of original granitic rocks that could be described as aceites. These alterations are accompanied by the enrichment in U, Ti, Mg, Ca, Na, K, Y, and Zr and depletion in Si, Ba, and Sr. The analyzed coffinite is enriched in Y (up to 3.1 wt % Y2O3). Uraninite is enriched in Th (up to 9.8 wt % ThO2) and thorite is enriched in Zr (up to 5.7 wt % ZrO2). The REE-elements are concentrated in the REE-fluorcarbonate synchysite-(Ce).

Sign in / Sign up

Export Citation Format

Share Document