ASGP (2023), vol. 93: 229–249
THE EASTERN PART OF THE SAXOTHURINGIAN TERRANE CHARACTERIZED BY ZIRCON AND MONAZITE DATA FROM THE DOBOSZOWICE METAMORPHIC COMPLEX IN THE SUDETES (SW POLAND)
Mirosław JASTRZĘBSKI (1*), Andrzej ŻELAŹNIEWICZ (1), Wojciech STAWIKOWSKI (2), Bartosz BUDZYŃ (3) , Ewa KRZEMIŃSKA (4) , Katarzyna MACHOWIAK (5), Stanisław MADEJ (6), Dawid BIAŁEK (6), Jiří SLÁMA (7), Zbigniew CZUPYT (4) & Aleksandra JAŹWA (1)
1) Institute of Geological Sciences, Polish Academy of Sciences, Podwale 75, 50-449 Wrocław, Poland; e-mails: mjast@twarda.pan.pl, pansudet@pwr.edu.pl, aleksandra.jazwa@twarda.pan.pl
2) Adam Mickiewicz University, Faculty of Geographical and Geological Sciences, Institute of Geology, B. Krygowskiego 12, 61-680 Poznań, Poland; e-mail: wojst@amu.edu.pl
3) Institute of Geological Sciences, Polish Academy of Sciences, Research Centre in Kraków, Senacka 1, 31-002 Kraków, Poland; e-mail: ndbudzyn@cyf-kr.edu.pl
4) Polish Geological Institute - National Research Institute, Rakowiecka 4, 00-975 Warszawa, Poland; e-mails: ekrz@pgi.gov.pl, zczu@pgi.gov.pl
5) Poznań University of Technology, Institute of Civil Engineering, Piotrowo 5, 60-965 Poznań, Poland; e-mail: katarzyna.machowiak@put.poznan.pl
6) University of Wrocław, Institute of Geological Sciences, Maksa Borna 9, 50-204 Wrocław, Poland; e-mails: stanislaw.madej@uwr.edu.pl, dawid.bialek@uwr.edu.pl
7) The Czech Academy of Sciences, Institute of Geology, Rozvojová 269, Prague 6, 16500, Czech Republic; e-mail: slama@gli.cas.cz
*) Corresponding author
Jastrzębski, M., Żelaźniewicz, A., Stawikowski, W., Budzyń, B., Krzemińska, E., Machowiak, K., Madej, S., Białek, D., Sláma, J., Czupyt, Z. & Jaźwa, A., 2023. The eastern part of the Saxothuringian Terrane characterized by zircon and monazite data from the Doboszowice Metamorphic Complex in the Sudetes (SW Poland). Annales Societatis Geologorum Poloniae, 93: 229–249.
Abstract: In the Variscan Bohemian Massif, orthogneiss complexes of different sizes, derived from early Palaeozoic granitoids, are accompanied by metavolcano-sedimentary successions. They are common in the Sudetes, SW Poland, and belong mainly to the Saxothuringian Terrane. In order to better characterize the evolution of the latter, new U-Pb and O isotopic zircon analyses, combined with zircon typology and new U-Th-Pb isotopic monazite analyses, were performed. The present data show that the S-type granitic precursors of the Doboszowice orthogneisses (Fore-Sudetic Block) and the Śnieżnik gneisses (Sudetes) were formed at ca. 495 Ma from differently evolved magmas. Protoliths of the Doboszowice orthogneisses developed entirely in the crust, whereas the precursors to the Śnieżnik gneisses received some mantle input. Metasediments that accompany the Doboszowice orthogneisses reveal zircon spectra, which point to a late Cambrian-Early Ordovician sedimentary age. These spectra, in addition to predominant grains with Ediacaran ages, contain up to 10% of zircons dated at ca. 1.0 Ga. Therefore, it is suggested that the parent basin was supplied with detritus coming from areas, located in the Libyan-Nubian part of North Africa. Using also earlier published data, such a provenance is assigned to the units that now occur in the eastern part of the Fore-Sudetic Block. Late Cambrian-Early Ordovician granite intrusions and the concurrent accumulation of sediments originated in an extensional setting of the peri-Gondwana rifted continental margin or a back-arc setting. The Pb/U and Pb/Th monazite data constrain the ca. 346–341-Ma peak of the Variscan regional metamorphism in the eastern Saxothuringian Terrane and the prolonged juxtaposition of now adjacent tectonic units at least until 330 Ma.
Bohemian Massif; Doboszowice Metamorphic Complex; Saxothuringian Terrane; isotope geochronology; Cambro-Ordovician magmatism, Variscan collision
Manuscript received 11 July 2022, accepted 22 April 2023
