Isotopic Re-Os age of molybdenite from the Szklarska Poręba Huta Quarry (Karkonosze, SW Poland)

Abstract

. (2012) -Iso to pic Re-Os age of mo lyb de nite from the Szklarska Porêba Huta Quarry (Karkonosze, SW Po land). Geol. Quart., 56 (3): 505-512, doi: 10.7306/gq.1036New Re/Os iso to pic data for mo lyb de nite from the Szklarska Porêba Huta Quarry pro vide ages of 307 ± 2 Ma and 309 ± 2 Ma, re spectively. The quarry is dom i nated by the por phy ritic ("cen tral") and equigranular ("ridge") va ri et ies of the Karkonosze gran ite. Ore min erali sa tion hosted in aplogranite in cludes an as sem blage of sulphides, sulphosalts, ox ides and var i ous rare phases. The mo lyb de nite ages ob tained are con sis tent with a pre vi ously pub lished iso to pic age of leucogranite (aplogranite?) from the same quarry and are only slightly older than a re cently pub lished, re fined 206 Pb/ 238 U age of un treated zir cons from the Szklarska Porêba Huta por phy ritic gran ite. The age of the mo lyb de nite cor re sponds mod er ately well to the youn ger stage of post-mag matic, pneumatolitic/hy dro ther mal ac tiv ity of the Karkonosze gran ite (about 312 Ma).

Deciphering the geochronology of a large granitoid pluton (Karkonosze Granite, SW Poland): an assessment of U–Pb zircon SIMS and Rb–Sr whole-rock dates relative to U–Pb zircon CA-ID-TIMS

“…It is noticed that the sample dated at 326 ± 1 Ma was taken from a "single big crystal aggregate up to 20 mm in diameter" (Mikulski and Stein 2007, p. 209), which might have proved uneasy to perfectly homogenize. The rest of published Re-Os ages, all slightly younger than 312 Ma (from 307 Ma to 310 Ma, as compiled by Mayer et al 2012) are in fair agreement with our best estimate for the igneous emplacement age, bearing in mind that molybdenite crystallized at a relatively late stage, during hydrothermal ore mineralization.…”

“…Both ages are consistent with the age of the vein-type molybdenite from the same locality reported by Mikulski and Stein (2011). These results were interpreted to indicate penecontemporaneous crystallization of molybdenite (at least part of it) and of the host aplogranite (Mayer et al 2012).…”

“…These very precise individual Re-Os ages display a 16 ± 2 Ma scatter. Recently, Mayer et al (2012) obtained two slightly younger dates of 307 ± 2 Ma and 309 ± 2 Ma on molybdenite disseminated in aplogranite from the Szklarska Poręba Huta quarry (analyses on molybdenite separates). Both ages are consistent with the age of the vein-type molybdenite from the same locality reported by Mikulski and Stein (2011).…”

Zircon U-Pb Dating of Magmatism and Mineralizing Hydrothermal Activity in the Variscan Karkonosze Massif and Its Eastern Metamorphic Cover (SW Poland)

“…Comparison of the U-Pb data with Re-Os dating of sulfides (mainly molybdenites) from the same sites in the Karkonosze massif and in the Eastern Karkonosze [5,6,87,88] (Figure 12) provides insights into the mineralization process. Comparison with the molybdenite data reveals both age similarities and small differences, recognizing that two different radiometric clocks, U-Pb and Re-Os, are recording the timing of crystallization of two different minerals in a complex magmatic setting.…”

Geochemical evolution of a composite pluton: insight from major and trace element chemistry of titanite

“…The late-to post-magmatic stage, reflected in various alteration of primary minerals and abundant mineralization, has been documented in many rock varieties from the Karkonosze pluton (Mochnacka and Banaś 2000;Pieczka and Gołębiowska 2002;Mikulski et al 2004;Słaby 2005;Kusiak et al 2009;Mochnacka et al 2015;Matyszczak 2018;Gros et al 2020). Several attempts of dating the hydrothermal activity provided ages, among others, of 309 ± 2 (Re-Os in molybdenite, Mayer et al 2012), 304 ± 2 (SHRIMP U-Pb in zircon, Kusiak et al 2009) and 271 ± 20 Ma (CHIME of monazite and xenotime, Mikulski et al 2004). Considering this wide range of obtained ages and their comparison with the average magmatic age of the pluton, the fluids must have circulated within the system over an extended period of time, leaving traces of their presence in many minerals.…”