Abstract This paper summarizes the current knowledge on the nature, kinematics and timing of movement along major tectonic boundaries in the Bohemian Massif and demonstrates how the Variscan plutonism and deformation evolved in space and time. Four main episodes are recognized: (1) Late Devonian–early Carboniferous subduction and continental underthrusting of the Saxothuringian Unit beneath the Teplá–Barrandian Unit resulted in the orogen-perpendicular shortening and growth of an inboard magmatic arc during c. 354–346 Ma; (2) the subduction-driven shortening was replaced by collapse of the Teplá–Barrandian upper crust, exhumation of the high-grade (Moldanubian) core of the orogen at c. 346–337 Ma and by dextral strike-slip along orogen-perpendicular NW–SE shear zones; (3) following closure of a Rhenohercynian Ocean basin, the Brunia microplate was underthrust beneath the eastern flank of the Saxothuringian/Teplá–Barrandian/Moldanubian ‘assemblage’; this process commenced at c. 346 Ma in the NE and ceased at c. 335 Ma in the SW; and (4) late readjustments within the amalgamated Bohemian Massif included crustal exhumation and mainly S-type granite plutonism along the edge of the Brunia indentor at c. 330–327 Ma, and peripheral tectonothermal activity driven by strike-slip faulting and possibly mantle delamination around the consolidated Bohemian Massif's interior until late Carboniferous–earliest Permian times.

Sediment provenances and magmatic events of Late Neoproterozoic (Ediacaran) and Cambro-Ordovician rock complexes from the Saxo-Thuringian zone are constrained by new laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb dating of detrital zircons from five sandstones and magmatic zircons from an ignimbrite and one tuffite. These geochronological results in combination with the analysis of the plate-tectonic setting constrained from field observations, sedimentological and geochemical data, and trends of the basin development are used to reconstruct Cadomian orogenic processes during the Late Neoproterozoic and the earliest Cambrian. A continuum between Cadomian orogenesis and the opening of the Rheic Ocean in the Cambro-Ordovician is supported by the data set. In our model, the early stage of the Cadomian evolution is characterized by a Cordilleran-type continental magmatic arc, which was established at the periphery of the West African craton between ca. 650 and 600 Ma. Subsequently, at ca. 590–560 Ma, a back-arc basin was formed behind the Cadomian magmatic arc. The back-arc basin was closed between ca. 545 and 540 Ma, leading to the development of a short-lived Cadomian retroarc basin. Subsequently, a mid-oceanic ridge was subducted underneath the Cadomian orogen. Slab break-off of the subducted oceanic plate resulted in increased heat flow, leading to voluminous magmatic and anatectic events that culminated at ca. 540 Ma. Oblique incision of the oceanic ridge into the continent caused the formation of rift basins during the Lower to Middle Cambrian. This process continued from the Middle to Upper Cambrian, finally caused the opening of the Rheic Ocean in the Lower Ordovician.

The Lausitz Group in the easternmost part of Saxo-Thuringia, Germany, forms the largest exposure of partly anchimetamorphic Cadomian basement in Germany. In common with adjoining units to the west, it was deposited in a convergent-margin basin of northern peri-Gondwana. Sedimentary features within the turbiditic graywacke successions suggest continuous accumulation during a deepening stage that followed basaltic-andesitic arc-volcanic activity. The turbidites are irregularly intercalated with tuffaceous graywacke, which was derived from reworked, but only slightly older, basic volcanic material. Petrological and geochemical data reveal a broadly uniform source area for the graywackes with a dissected magmatic arc signature containing exhumed pre-Cadomian basement. Graywackes of the Lausitz Group together with earlier Cadomian basin successions and parts of the pre-Cadomian basement became mobilized during Cadomian subduction-related anatexis. During basin closure, the graywackes were weakly folded with a northerly vergence. Subsequently, they were contact-metamorphic overprinted by granodioritic intrusions, which mark the end of the Cadomian orogeny and show both Cadomian and pre-Cadomian crustal signatures. Superimposed very low-grade S-C textures in gray-wackes of the eastern Lausitz area are due to Variscan processes.

The Saxo-Thuringian zone of the European Variscides contains the record of the Cadomian and Variscan orogenies and a Paleozoic marine transition stage. The classical view of a relatively simple, double-vergent folded sedimentary basin at the end of the Early Carboniferous is challenged by the widespread occurrence of Late Devonian to Early Carboniferous high-pressure metamorphic units tectonically juxtaposed with low-grade Paleozoic successions. Here we demonstrate that the subdivision of the Saxo-Thuringian zone in three principal units (autochthonous domain, wrench and thrust zone, and allochthonous domain) and their heterogeneous overprint by two regional deformation events during the Variscan orogeny explain the entire geological record. Late Devonian to Early Carboniferous subduction of continental crust inside the allochthonous domain affected a Cadomian basement and sediments deposited on the same continental shelf as the one preserved in the autochthonous domain. Strain partitioning during this regional D1 process led to the formation and evolution of a wrench and thrust zone surrounding the autochthonous domain. The latter was only affected by regional D2 deformation, which was related to regional dextral transpression, rapid exhumation of the subducted rocks of the allochthonous domain, and final filling and subsequent folding of the Saxo-Thuringian flysch basin that covers the autochthonous domain and the wrench and thrust zone. The Saxo-Thuringian zone is interpreted as a fragment of Peri-Gondwana that never separated from Gondwana to move as an independent terrane and that borders to the Old Red continent, represented by the Rheno-Hercynian zone, along a strike-slip dominated segment of the Rheic suture. The juxtaposition of the Saxo-Thuringian zone with the adjacent areas is discussed as a continuous subduction and/or accretion process representative for the entire Variscan orogen.

Ca. 500 Ma orthogneisses and bimodal suites are widespread along the northern part of the Bohemian Massif (central European Variscides) and are interpreted to document intense magmatism during a continental break-up episode along the northern periphery of Gondwana. Based on geological setting, and geochemical and isotopic evidence, these felsic igneous rocks record the generation of: (1) magmas of pure or predominantly crustal derivation, represented by minor extrusives and much more voluminous orthogneisses similar to S-type granitoids; (2) subordinate magmas of exclusively mantle origin (ranging from within-plate alkali trachytes to oceanic plagiogranites) corresponding to felsic derivatives of associated basalts; and (3) magmas of hybrid origin, produced either as a result of large degrees of contamination of mantle-derived magmas ascending through the crust, or alternatively, generated by partial melting of mixed sources, such as interlayered sediments and mafic rocks or graywackes containing a juvenile component. The high-temperature dehydration melting process responsible for the generation of the most abundant rock-types necessitated the advection of mantle heat, in a context of continental lithosphere extension, as documented by broadly coeval basaltic magmatism at the scale of the igneous province. The large volumes of felsic magmas generated during the 500-Ma anorogenic event are interpreted to result from the combination of a hot extensional tectonic regime with the widespread availability in the lower crust of fertile lithologies, such as metagraywackes. This in turn reflects the largely undifferentiated nature of the crustal segment accreted some 50–100 m.y. earlier during the Cadomian orogeny.