First Permian-Early Triassic zircon ages for tin-bearing granites from the Gemeric unit (Western Carpathians, Slovakia): connection to the post-collisional extension of the Variscan orogen and S-type granite magmatism

Terra Nova ◽  
2002 ◽  
Vol 14 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Ulrike Poller ◽  
Pavel Uher ◽  
Igor Broska ◽  
Dusan Plasienka ◽  
Marian Janak
2020 ◽  
Author(s):  
Igor Broska ◽  
Keewook Yi ◽  
Milan Kohút ◽  
Igor Petrík

<p>The granites with I- and S-type affinity in the Variscan segments of the Alpine West-Carpathian edifice belong to the oldest intrusions within the European Variscides. Granites and granodiorites of the West-Carpathian crystalline basement are mostly classified as S-type, whereas tonalities and granodiorites belong to the I-type suite. Both suites probably originated in the volcanic arc setting as product of subduction-related regime in the Galatian superterrane (Broska et al. 2013). The I- and S-type granite bodies were firstly identified in the West-Carpathian Tribeč Core Mountains and the new SHRIMP and CHIME datings recognised their Visean geotectonic overprint. The subduction-related I-type granites show the age span 364-358 Ma followed by the intrusion of the S-type granites dated by SHRIMP on 358 Ma. The bimodal SHRIMP data of a dyke placed within S-type granites show ages 351 Ma and 330 Ma, or primary vs. alteration age. The CHIME age from monazite dating shows 347 Ma because monazite indicate probably early stage of massive granite alteration perhaps during collisional process, younger zircons represents later phase of the event.  CHIME dating of newly formed monazite in greisenised S-type granite gives the age 344 Ma. The granite showing strong greisenization (total degradation of feldspars and formation of quartz - white mica assemblages) is dated by SHRIMP on 355 Ma. The greisenised granite contains abundant tourmaline with high dravitic molecule, Sr-rich apatite and common monazite. Abundant tiny stoichiometrically pure apatite grains in this granite indicate their exsolution from feldspars enriched in phosphorus. The S-type granite dyke from the ridge of the Tribeč Mts gives zircon SHRIMP age 355 Ma and CHIME monazite age 342 Ma. The dating results of the Tribeč granites identified: (<strong>1</strong>) older Upper Devonian/Lower Mississippian subduction-related I-type tonalites (ca. 364-351 Ma), and (<strong>2</strong>) S-type granites Middle/Upper Mississippian (Visean) intruding in time span 342-330 Ma reflecting probably of the collisional event in the Variscan orogeny. Dual evolution of the Tribeč Mts. Variscan granitic rocks is partly corroborated by Hf isotopes from the dated zircons with εHf<sub>(t)</sub> = +3.5 ~ –2.4 for the older granites, and εHf<sub>(t)</sub> = –0.3 ~ –4.9 for the younger ones. The evolution of the I- and S-type granites seems to be rather different from the granite evolution known in the Bohemian Massif and therefore the origin of Variscan hybrid granites from the Western Carpathians we placed on the SW side of Galatian volcanic arc as result of Paleo-Tethys subduction (see Stampfli and Borel, 2002, Stampfli et al. 2013).</p><p>Acknowledgments: Support from Slovak Research and Development Agency: APVV SK-KR-18-0008, APVV-14-0278/, APVV-18-0107, and VEGA 2/0075/20 are greatly appreciated.</p>


2011 ◽  
Vol 101 (4) ◽  
pp. 919-936 ◽  
Author(s):  
Anna Vozárová ◽  
Katarína Šarinová ◽  
Nickolay Rodionov ◽  
Dušan Laurinc ◽  
Ilya Paderin ◽  
...  

Lithos ◽  
2015 ◽  
Vol 236-237 ◽  
pp. 212-225 ◽  
Author(s):  
Pavel Uher ◽  
Martin Ondrejka ◽  
Peter Bačík ◽  
Igor Broska ◽  
Patrik Konečný

2013 ◽  
Vol 64 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Milan Kohút ◽  
Holly Stein ◽  
Pavel Uher ◽  
Aaron Aimmerman ◽  
L’ubomír Hraško

Abstract The subsurface Rochovce granite intrusion was emplaced into the contact zone between two principal tectonic units (the Veporic Unit and the Gemeric Unit) of the Central Western Carpathians (CWC), Slovakia. The Cretaceous age of this granite and its Mo-W mineralization is shown using two independent methods: U-Pb on zircon and Re-Os on molybdenite. The studied zircons have a typical homogeneous character with oscillatory zoning and scarce restite cores. SHRIMP U-Pb data provide an age of 81.5 ± 0.7 Ma, whereas restite cores suggest a latest Neoproterozoic-Ediacaran age (~565 Ma) source. Zircon εHf(81) values -5.2 to + 0.2 suggest a lower crustal source, whereas one from the Neoproterozoic core εHf(565)= + 7.4 call for the mantle influenced old precursor. Two molybdenite- bearing samples of very different character affirm a genetic relation between W-Mo mineralization and the Rochovce granite. One sample, a quartz-molybdenite vein from the exocontact (altered quartz-sericite schist of the Ochtiná Formation), provides a Re-Os age of 81.4 ± 0.3 Ma. The second molybdenite occurs as 1-2 mm disseminations in finegrained granite, and provides an age of 81.6 ± 0.3 Ma. Both Re-Os ages are identical within their 2-sigma analytical uncertainty and suggest rapid exhumation as a consequence of post-collisional, orogen-parallel extension and unroofing. The Rochovce granite represents the northernmost occurrence of Cretaceous calc-alkaline magmatism with Mo-W mineralization associated with the Alpine-Balkan-Carpathian-Dinaride metallogenic belt.


2017 ◽  
Vol 155 (4) ◽  
pp. 955-978 ◽  
Author(s):  
A. PRAKASH ◽  
L. SAHA ◽  
I. PETRIK ◽  
M. JANAK ◽  
A. BHATTACHARYA

AbstractGarnetiferous pelitic to psammopelitic migmatites widespread across the central and eastern part of the Aravalli–Delhi Fold Belt in NW India record two distinct orogenies, e.g. the Aravalli Orogeny (1.7–1.6 Ga) and the Delhi Orogeny (1.0 Ga). In this study, we integrate field geological studies with textural and mineral–chemical analyses,P–Tpseudosection modelling andin situmonazite dating in anatectic migmatites in the Aravalli Supergroup occurring along the Deoli–Shahpura segment. The study reveals formation of peak assemblages of garnet + sillimanite + biotite + K-feldspar + melt and garnet + muscovite + K-feldspar + melt in two anatectic migmatite samples.P–Tpseudosection modelling suggests that anatexis in the gneisses occurred at ~8 kbar and 700–800°C along a tight-loop clockwiseP–Tpath. Monazite ages from the migmatites indicate that the anatexis occurred at ~1.73–1.74 Ga. This age is similar to the Palaeoproterozoic anatexis (at 7–8 kbar) and charnockite emplacement in the Sandmata and the Mangalwar complexes, the subsolidus amphibolite-facies metamorphism in the Rajpura–Dariba and Pur–Banera supracrustal belts, and the A-type granite magmatism in the North Delhi Fold Belt. We propose that the Palaeoproterozoic migmatites in central and eastern Rajasthan are part of the one crustal unit that underwent anatexis during an accretion event along the NE–SW-trending Aravalli orogenic belt.


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