The late‑Variscan high‑temperature collisional episode in the southwestern Moldanubian Zone (Bohemian Massif)

0569487 - GLÚ 2024 RIV DE eng J - Journal Article
Megerssa, L. - Verner, K. - Buriánek, D. - Pour, O. - Tomek, Filip - Schiller, D. - Martínek, K.
The late‑Variscan high‑temperature collisional episode in the southwestern Moldanubian Zone (Bohemian Massif).
International Journal of Earth Sciences. Roč. 112, č. 2 (2023), s. 631-658. ISSN 1437-3254. E-ISSN 1437-3262
Grant - others:AV ČR(CZ) L100131601
Program: Post-doctoral fellowship, program supporting perspective human sources
Institutional support: RVO:67985831
Keywords : Bohemian Massif * Moldanubian Zone * Thermobarometry * Anisotropy of magnetic susceptibility * Fabric pattern
OECD category: Geology
Impact factor: 2.3, year: 2022
Method of publishing: Limited access
https://link.springer.com/article/10.1007/s00531-022-02258-2

This paper presents new structural, anisotropy of magnetic susceptibility (AMS), and petrological data in tandem with existing geochronological data to determine a polyphase Variscan tectonometamorphic event in the southwestern Moldanubian Zone of the Bohemian Massif. The high-grade metamorphic rocks of this Zone underwent the successive tectonometamorphic evolution (from ca. 360 to 310 Ma) that portrays three main geodynamic episodes: (a) The collisional to exhumation episode (ca. 360–335 Ma) recorded by the relict, steeply dipping, and ~ N(NNE) to S(SSW) striking foliation planes (S₁) developed at temperatures of 720–754 °C and pressures of ca. 790 MPa (M₁) and superimposed flat-lying foliation planes (S₂) under temperatures of 674 ± 27 °C and pressures of 680 ± 110 MPa (M₂). (b) The late-orogenic ~ N–S oriented shortening (ca. 335–325 Ma) controlled by convergence of a crustal segment derived from the Gondwana continent (newly named as the “Salzburgia Block) and the mostly consolidated Bohemian Massif. These collisional processes resulted in superimposition of the foliation planes (S₃) dipping steeply to moderately to the ~ N to ~ NNE(NE), re-heating and metamorphic overprint at temperatures of 770–830 °C and pressures of 450–530 MPa (M₃) and syn-tectonic emplacement of the numerous late-orogenic granitoids. (c) Subsequently, the switch in the paleostress regime from ~ N–S shortening to that of late-orogenic ~ ENE–WSW extension (ca. 325–310 Ma) led to the activation of regional right-lateral transtension and exhumation of the deep-seated rocks. Associated re-equilibration proceeded under temperatures of 662–701 °C and pressures of 362–437 MPa (M₄ event). In the latter stages of this episode, the synchronous reactivation of the regional ~ NW–SE striking right-lateral shear zones (Pfahl and Danube) and the almost perpendicular ~ NNE(NE)–SSW(SW) striking left-lateral shear zones took place.
Permanent Link: https://hdl.handle.net/11104/0340911