Dynamics of Cambro–Ordovician rifting of the northern margin of Gondwana as revealed by the timing of subsidence and magmatism in rift-related basins

0576203 - GLÚ 2024 RIV GB eng J - Journal Article
Žák, J. - Sláma, Jiří - Syahputra, R. - Nance, R. D.
Dynamics of Cambro–Ordovician rifting of the northern margin of Gondwana as revealed by the timing of subsidence and magmatism in rift-related basins.
International Geology Review. Roč. 65, č. 19 (2023), s. 3004-3027. ISSN 0020-6814. E-ISSN 1938-2839
Institutional support: RVO:67985831
Keywords : Avalonian–Cadomian belt * Bohemian Massif * hyperextension * passive margin * Rheic Ocean * laser ablation ICP-MS * U–Pb zircon geochronology * rifting
OECD category: Geology
Impact factor: 2.6, year: 2022
Method of publishing: Limited access
https://www.tandfonline.com/doi/abs/10.1080/00206814.2023.2172619

The Bohemian Massif of Central Europe is a Variscan collage of lithospheric fragments that formed at the northern margin of Gondwana during the late Neoproterozoic. A key geodynamic process that shaped this margin before it became involved in the Variscan orogen was the Cambro–Ordovician rifting that opened the Rheic Ocean. This rifting event has been studied extensively, yet a number of issues remain unresolved, among which are its geodynamic causes. New U–Pb zircon ages of orthogneisses from the mid-crustal Moldanubian unit, in combination with available information on magmatism and basin subsidence in the upper-crustal Teplá–Barrandian unit of the Bohemian Massif, are here used to reconstruct in detail the mechanism of the Cambro–Ordovician rifting. We argue that extension occurred in three phases defined by (1) protracted ~524–480 Ma intermediate to felsic plutonism (including the dated ~490–480 Ma orthogneisses), (2) basaltic submarine volcanism at ca. 470 Ma, and (3) rapid subsidence at ca. 458–452 Ma. This relative timing is interpreted to reflect stretching of the lower lithosphere before upper lithospheric rifting. In a broader context, these inferences are compatible with contrasting, rheologically controlled modes of northern Gondwana break-up during the early Ordovician, in which the westerly Avalonian-type terranes were rifted away from Gondwana, whereas the easterly Cadomian-type terranes formed a hyperextended Gondwanan shelf.
Permanent Link: https://hdl.handle.net/11104/0345793