Long-lasting Cadomian magmatic activity along an active northern Gondwana margin: U–Pb zircon and Sr–Nd isotopic evidence from the Brunovistulian Domain, eastern Bohemian Massif

Neoproterozoic crystalline exotic clasts in the Polish Outer Carpathian flysch: remnants of the Proto-Carpathian continent?

“…Finger et al 1999), in the Cadomian/Pan-African massifs of Western Europe (Linneman et al 2014), and the Cetic Massif in the Alps (Frasl and Finger 1988;Neubauer and Handler 2000) suggest that Pan-African/Cadomian/Timanian magmatic events were the only high-temperature events which affected these rocks and that eastern Brunovistulia was not involved in any younger tectono-thermal events. This supports the suggestion of Soejono et al (2017) that Brunovistulia was already accreted to Baltica in the Cambrian and represented a passive margin during Paleozoic times in contrast to Cadomian terranes within the Variscan Belt of Europe.…”

“…Earlier studies of exotic clasts from the Silesian Nappe also yielded similar ages (610 ± 6 Ma; 604 ± 6 Ma and 599 ± 6 Ma; Budzyń et al 2011; 580 ± 6 Ma and 542 ± 21 Ma; Burda et al 2019) potentially also implying a linkage between the Silesian Ridge and Brunovistulia. The granite from Nowe Rybie yields the youngest age in this study (565.5 ± 2.9 Ma) and overlaps in age with the youngest age population obtained from the basement of the Upper Silesia Coal basin and exotic clasts of inferred Brunovistulian provenance in the Outer Carpathians (Burda et al 2019), Cadomian pebbles within glaciomarine deposits on the Bohemian massif (Linneman et al 2018), as well as the Svratka Dome metagranite from Brunovistulia, which also shares a similar age and geochemistry (Soejono et al 2017). These data support inferences that the Proto-Carpathian basement represents the eastern continuation of Brunovistulia.…”

“…Inherited zircon core ages of c. 1320 Ma and c. 1770 Ma (Fig. 9b) are similar in age to Mesoproterozoic ages from gneissic/metagranitoid exotic blocks and zircon xenocrystic core ages from the eastern part of the Silesian Nappe (Michalik et al 2006), to zircon xenocrystic core ages from the Brunovistulian basement in the Svratka Dome in the Czech Republic (Soejono et al 2017). The peraluminous, weakly fractionated Nowe Rybie granite shows a calc-alkaline character in contrast to the high-K calc-alkaline Istebna orthogneisses ( Fig.…”

“…These Late Neoproterozoic basement terranes formed a result of the assembly of the Pannotia supercontinent (Dalziel et al 1994;Golonka et al 2006 and references therein) and the majority of them exhibit Variscan reworking (e.g. Soejono et al 2017).…”

“…Brunovistulia has been divided into the Thaya and Slavkov terranes by a N-S trending ophiolite belt (725 ± 15 Ma;Finger et al, 1999), which were intruded by granitoids, representing prolonged (568-634 Ma) subduction-related magmatism (Soejono et al 2017 and references therein). Brunovistulian orthogneisses are characterized by collision-related granitoid protoliths dated at 612.7 ± 1.0 Ma, 601 ± 3 and 634 ± 6 (Kröner et al 2000, Linnemann et al 2008Soejono et al 2017), while paragneisses have yielded metamorphic monazite total Pb ages of 608 ± 28 Ma, 577 ± 19 Ma and 549 ± 19 Ma (Finger et al 1999). Granitoids from boreholes which penetrate the basement in the Upper Silesia Coal Basin below the Outer Carpathian overthrust, yield similar U-Pb zircon ages (573 ± 3 Ma from the Kęty-8 borehole, 544 ± 4 Ma from the Roczyny-3 borehole; Żelaźniewicz et al 2002;Linnemann et al 2008).…”