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

0478000 - GLÚ 2018 RIV DE eng J - Journal Article
Soejono, I. - Janoušek, V. - Žáčková, E. - Sláma, Jiří - Konopásek, J. - Machek, Matěj - Hanžl, P.
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.
International Journal of Earth Sciences. Roč. 106, č. 6 (2017), s. 2109-2129. ISSN 1437-3254. E-ISSN 1437-3262
Institutional support: RVO:67985530 ; RVO:67985831
Keywords : Cadomian magmatic arc * Brunovistulian Domain * Bohemian Massif * Gondwana margin * U–Pb geochronology * geochemistry
OECD category: Geology; Volcanology (GFU-E)
Impact factor: 2.276, year: 2017

Cadomian magmatic complexes of the Brunovistulian Domain crop out at the eastern termination of the Bohemian Massif. However, the age, nature and geotectonic affinity of some of pre-Variscan (meta-)igneous rock complexes from this domain are still unknown. Geochronological and geochemical study of the granitic rocks across the Brunovistulian Domain reveals new information about the timing and nature of this magmatic activity originally situated along the northern margin of Gondwana. Zircon U-Pb data (601 +/- 3 Ma, Brno Massif, 634 +/- 6 Ma, paraautochtonous core of the Svratka Dome, 568 +/- 3 Ma, Bites orthogneiss) from the allochtonous Moravicum indicate the prolonged magmatic activity within the Brunovistulian Domain during the Ediacaran. The major- and trace-element and Sr-Nd isotopic signatures show heterogeneous geochemical characteristics of the granitic rocks and suggest a magmatic-arc geotectonic setting. The two-stage Depleted Mantle Nd model ages (c. 1.3-2.0 Ga) indicate derivation of the granitic rocks from a relatively primitive crustal source, as well as from an ancient and evolved continental crust of the Brunovistulian Domain. These results constrain the magmatic-arc activity to c. 635-570 Ma and provide a further evidence for a long-lived (at least c. 65 Myr) and likely episodic subduction-related magmatism at the northern margin of Gondwana. The presence of granitic intrusions derived from variously mature crustal sources at different times suggests heterogeneous crustal segments to having been involved in the magmatic-arc system during its multistage evolution.
Permanent Link: http://hdl.handle.net/11104/0274240