Re-Os and U-Th-Pb dating of the Rochovce granite and its mineralization (Western Carpathians, Slovakia)

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.

Initial replacement stage of primary uranium (UIV) minerals by supergene alteration: association of uranyl-oxide hydroxy-hydrates and “calciolepersonnite” from the Krátka Dolina Valley (Gemerská Poloma, Gemeric Unit, Western Carpathians, Slovakia)

“…Uraninite is the dominant primary mineral at all occurrences of U ores. systems connected with the Cretaceous Rochovce granite intrusion (Poller et al 2001;Kohút et al 2013). The most interesting occurrences of brannerite represent Gemeric quartz (± apatite) veins that contain U-REE mineralization in the Krátka Dolina Valley (near Gemerská Poloma), Peklisko (at the Hnilec village), and at the end of the Gelnická Dolina Valley (Zimná Voda occurrence) near Prakovce (Novotný and Čížek 1979;Rojkovič and Novotný 1993;Rojkovič et al 1997;Novotný et al 1999;Donát et al 2000).…”

The Late Cretaceous igneous rocks of Romania (Apuseni Mountains and Banat): the possible role of amphibole versus plagioclase deep fractionation in two different crustal terranes

“…Late Cretaceous magmatic rocks are also known from drillings in the Tatra Mts. of Slovakia (Kohut et al 2013) and in the north-eastern part of the Pannonian Basin (NE Hungary-NW Romania) (Berza and Ilinca 2014). In outcrop, a NE-SW orientation in the Apuseni Mts.…”

“…This, together with results obtained Electronic supplementary material The online version of this article (doi:10.1007/s00531-015-1210-2) contains supplementary material, which is available to authorized users. these ore deposits (Zimmerman et al 2008;Kohut et al 2013) and U-Pb LA-ICPMS ages obtained on the magmatic zircon (Nicolescu et al 1999;Von Quadt et al 2005;Georgiev et al 2012;Kohut et al 2013;Kolb et al 2013) indicate the following bracketing ages for intrusion and/ or molybdenite crystallization: Tatra The geodynamic setting of the Late Cretaceous magmatic rocks, named "banatites" (Von Cotta 1864), was mostly considered as subduction-related because of their calc-alkaline composition, their enrichment in LILE and depletion in Nb-Ta and the presence of a major oceanic remnant in the Carpathian-Balkan orogen, namely the Eastern Vardar Ocean (a branch of the Tethys Ocean) that is supposed to have subducted northward under the European margin during the Jurassic to Lower Cretaceous and to which the ophiolites of the Mureş zone (or Transylvanides) are linked (Schmid et al 2008) (Figs. 1, 2).…”

Geological evolution of the southwestern part of the Veporic Unit (Western Carpathians): based on fission track and morphotectonic data

“…With the ongoing collision, this fabric was folded. The southern boundary between the Veporic and Gemeric units was intruded by the subsurface Rochovce Granite of Cretaceous age (Hraško et al 1999;Poller et al 2001;Kohút et al 2013). The Alpine exhumation in the central part of the Veporic Unit took place during the Late Cretaceous to Palaeogene (Králiková 2013;Vojtko et al 2016).…”

“…Genetically, the mineralization is confined to pre-existing subvertical E-W trending cleavage and is related to intrusion of the subsurface Upper Cretaceous Rochovce granite occurring in the close proximity to the Lubeník thrust zone. It is dated by zircon U-Pb isochrones revealing ages from ~ 76 to 82 Ma (Hraško et al 1999;Poller et al 2001;Kohút et al 2013) and post-dates the (Ketcham 2005). Results are displayed in time-temperature diagrams (left diagrams).…”