Timing of post-collisional volcanism in the eastern part of the Variscan Belt: constraints from SHRIMP zircon dating of Permian rhyolites in the North-Sudetic Basin (SW Poland)

Abstract

The final stages of the Variscan orogeny in Central Europe were associated with voluminous granitic plutonism and widespread volcanism. Four samples representative of the main rhyolitic volcanic units from the Stephanian–Permian continental succession of the North-Sudetic Basin, in the eastern part of the Variscan Belt, were dated using the SIMS (SHRIMP) zircon method. Three samples show overlapping 206Pb–238U mean ages of 294 ± 3, 293 ± 2 and 292 ± 2 Ma, and constrain the age of the rhyolitic volcanism in the North-Sudetic Basin at 294–292 Ma. This age corresponds to the Early Permian – Sakmarian Stage and is consistent with the stratigraphic position of the lava units. The fourth sample dated at 288 ± 4 Ma reflects a minor, younger stage of (sub)volcanic activity in the Artinskian. The silicic activity was shortly followed by mafic volcanism. The rhyolite samples contained very few inherited zircons, possibly owing to limited contribution of crustal sources to the silicic magma, or owing to processes involved in anatectic melting and magma differentiation (e.g. resorption of old zircon by Zr-undersaturated melts). The SHRIMP results and the stratigraphic evidence suggest that the bimodal volcanism terminated the early, short-lived (10–15 Ma) and vigorous stage of basin evolution. The Permian volcanism in the North-Sudetic Basin may be correlated with relatively late phases of the regional climax of Late Palaeozoic volcanism in Central Europe, constrained by 41 published SHRIMP zircon age determinations at 299–291 Ma. The Permian volcanism and coeval plutonism in the NE part of the Bohemian Massif can be linked to late Variscan, post-collisional extension.

Multiphase magmatic activity in the Variscan Kłodzko–Złoty Stok intrusion, Polish Sudetes: evidence from SHRIMP U–Pb zircon ages

“…2 a Dominant lithology observed by us and Wierzchołowski (1976) (Krkonoše-Jizera pluton) to the SE (Žulová pluton). It could mark the start of the extensional tectonic regime followed by late Carboniferous-Permian volcanism (Awdankiewicz et al 2014;Turniak et al 2014). …”

“…7 Map of the post-collisional igneous activity in the Sudetes. Abbreviations and sources of ages: KJG Karkonosze-Jizera granite , SSM Strzegom-Sobótka Massif (Turniak et al 2014), ŽP Žulova pluton (Laurent et al 2014), SM Strzelin Massif (Oberc-Dziedzic and Kryza 2012), NSB North-Sudetic Basin (Awdankiewicz et al 2014), ISB Intra-Sudetic Basin (Oplustil et al 2016), SBF and ISF Sudetic boundary and intraSudetic faults. Note the pluton age progression from NW toward ES along the faults.…”

A Gyűrűfűi Riolit Formáció kőzettani vizsgálatának eredményei a Villányi-hegység északi előterében

“…Erdélyi-szigethegység, Észak-Gömöri -kum, Észak-Veporikum, Intra-Szudéta-medence, Dél-Permi-me den ce) permokarbon savanyú-intermedier vulkanitjairól ren delkezésünkre álló ismeretek integrálása. A fenti terü le tek permokarbon magmatizmusát gyakran többfázisú Abbreviations: bt: biotite, chl: chlorite, fsp: feldspar, grt: garnet, zrn: zircon, 1N: parallel nicols, +N: crossed nicols ese ményként értelmezték, amelyet radiometrikus korada tok tá masztanak alá (AWDANKIEWICZ 1999, AWDANKIEWICZ & KRYZA 2010, NICOLAE et al 2014, VOZÁROVA et al 2015. A permokarbon vulkáni-üledékes-rétegsorokban mind a vul kanizmus mechanizmusában (szubvulkáni intrúziók, láva kő -zetek és piroklasztitok), mind annak kemizmusában gyak ran változó képződményeket tártak fel (pl.…”

A Permian andesitic tuff ring at Rožmitál (the Intra-Sudetic Basin, Czech Republic) – evolution from explosive to effusive and high-level intrusive activity

“…The fol low ing pe riod of extensional and wrench tec ton ics, pos si bly as so ci ated with orogenic delamination (Geiss ler et al, 2012), re sulted in the de vel op ment of nu mer ous con ti nen tal sed i men tary bas ins upon the de cay ing Variscan orogenic belt and its fore land. These bas ins ac com mo dated thick vol cano-sed i men tary suc ces sions of, dom i nantly, siliciclastic al lu vial de pos its in ter ca lated with mafic to silicic vol ca nic rocks dur ing the Car bon if er ous and Perm ian (e.g., Breitkreuz and Ken nedy, 1999;McCann et al, 2006;Breitkreuz et al, 2007;Timmerman, 2008;Awdankiewicz et al, 2014, and ref er ences cited there). The late-to post-collisional, wide spread and vo lu minous Permo-Car bon if er ous vol ca nism, to gether with co eval granitic plutonism, orig i nated due to orogenic delamination, man tle upwelling and melt ing, underplating of man tle melts, crustal anatexis, as well as ex ten sive dif fer en ti a tion of the man tle melts at shal low lithospheric lev els (Fin ger et al, 1997;Wil son et al, 2004;Ziegler and DÀzes, 2006;Mazur et al, 2007;Timmerman, 2008;Geiss ler et al, 2012;Oberc-Dziedzic et al, 2013a, b).…”