Dating of detrital zircons and tracing the provenance of quartzites from the Bystrzyckie Mts: implications for the tectonic setting of the Early Palaeozoic sedimentary basin developed on the Gondwana margin

Abstract

We studied the petrographical characteristics and bulk chemical composition along with the age of detrital zircon grains from quartzites exposed in the western part of the Orlica-Śnieżnik dome in the Saxothuringian zone. Age spectra of detrital zircons were obtained by U–Pb laser ablation inductively coupled plasma mass spectrometry dating. The zircon ages define a few clusters of which the most numerous are Cambro-Ordovician and Neoproterozoic, and less frequent are Paleoproterozoic and Archean. A distinctive feature of the investigated samples is the lack of Mesoproterozoic zircon grains. The youngest age cluster documented in the investigated quartzites points to a Late Cambrian maximum depositional age and detritus derivation from erosion of Cambro-Ordovician metagranitoids. Bulk chemical composition of the quartzites indicates that they originated owing to erosion of granite within sedimentary basins developed on a passive continental margin. Presented data prove the similarity of the examined rocks to quartzites known from the eastern part of the Orlica-Śnieżnik dome and quartz metasandstones documented in other parts of the Variscan Belt of Europe known as the Armorican quartzites or their equivalents exposed in the Saxothuringian zone. Our results support the suggestion that the Orlica-Śnieżnik dome has an affinity to the West African Craton of the Gondwana margin and represents a fragment of the Saxothuringian zone.