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In the Variscan Bohemian Massif, (ultra-)potassic plutons are conspicuously associated with the high-grade, lower crustal/upper mantle Gfohl Unit (Moldanubian Zone). They can be subdivided into two contrasting groups: (1) coarse amphibole–biotite melagranite to quartz syenite with conspicuous K-feldspar phenocrysts (the ‘durbachite suite’), and (2) essentially equigranular biotite–two-pyroxene quartz syenites to melagranites (the ‘syenitoid suite’). The latter suite, represented by the Tabor and Jihlava plutons, is characterized by an originally ‘drier’ mineral assemblage orthopyroxene + clinopyroxene + Mg-biotite + plagioclase + K-feldspar + quartz, with accessory zircon, apatite, ilmenite, monazite and/or rutile + chromite. The rich assemblage of both rock-forming and accessory minerals allows testing of numerous geothermobarometers. The resulting P–T data are mutually consistent; they document emplacement of the parental magmas at mid-crustal levels (~5 kbar/19 km for Tabor and 7–8 kbar/26–30 km for Jihlava) and record near-isobaric crystallization from at least 1170 °C to the solidus. New Isotope-Dilution Thermal Ionization Mass-Spectrometry (ID-TIMS) U–Pb ages for zircon (336.9 + 0.6 Ma) and rutile (336.8 + 0.8 Ma) from the Tabor Pluton, together with previously published ages from the Jihlava Pluton, provide temporal constraints for the emplacement and rapid cooling of the syenitoids below c. 600 °C. This supports the hypothesis of post-tectonic emplacement of a hot and dry melt (>1200 °C?) into an essentially consolidated orogenic crust. The two syenitoid plutons have comparable, crust-like radiogenic isotope signatures (87Sr/86Sr337 = 0.7114–0.7133, e337Nd = −6.8 to −8.0). This, in context of whole-rock geochemical variation and K-feldspar Pb isotopic compositions, is consistent with generation from a strongly enriched lithospheric mantle source. Shortly before melting, the local orogenic mantle was most likely modified by deep subduction and relamination of felsic crustal material of the Saxothuringian provenance, transformed to the felsic high-pressure granulites common in the Moldanubian Zone. In the subsequent evolution of the two-pyroxene syenitoid plutons, crystal fractionation and accumulation played a key role, unlike in the durbachite suite itself, where magma mixing with leucogranitic melts was much more important. Structural relations inside and around the (ultra-)potassic plutons (~343–335 Ma) suggest that – besides different depths and specific processes of magma emplacement – these plutons track different kinematic histories and evolutions of regional strain fields in their high-grade country rocks in this crucial period of the Variscan Orogeny.

Garnet and zircon geochronology combined with trace element partitioning and petrological studies provide tight constraints on evolution of the UHT-(U)HP terrain of the Orlica-Śnieznik Dome (OSD) in the NE Bohemian massif. Lu-Hf dating of peritectic garnet from two mesocratic granulites constrained the time of its initial growth at 346.9 ± 1.2 and 348.3 ± 2.0 Ma recording peak 2.5 GPa pressure and 950 °C temperature. In situ, U-Pb SHRIMP dating of zircon from the same granulite gave a younger age of 341.9 ± 3.4 Ma. Ti-in-zircon thermometry indicates crystallization at 810–860 °C pointing to zircon formation on the retrograde path. Lu partitioning between garnet rim and zircon suggest equilibrium growth and thus U-Pb zircon age constrain the terminal phase of garnet crystallization which lasted about 6 Ma. All Sm-Nd garnet ages obtained for mesocratic and mafic granulites are identical and consistently younger than the corresponding Lu-Hf dates. They are interpreted as reflecting cooling of granulites through the Sm-Nd closure temperature at about 337 Ma. The estimated PTt path documents the ca. 10 Ma evolution cycle of the OSD characterized by two distinct periods: (1) 347 - > 342 Ma period corresponds to nearly isothermal decompression resulting from crustal scale folding and vertical extrusion of granulites, and (2) at > 342–337 Ma which corresponds to a fast, nearly isobaric cooling.

A new data set of ca. 500 LA–ICP-MS U–Pb detrital zircon ages for six metasedimentary units from the Tuscan basement (Apuan Alps, Monti Pisani, Monticiano-Roccastrada), along with a precise SHRIMP U–Pb crystallization age of a metavolcanic unit (Apuan Alps) have been collected to determine their depositional ages and provenance. These results have been integrated with the recently published ca. 900 U–Pb detrital zircon ages from Elba Island to draw a complete picture of the Paleozoic journey of the Tuscan basement. A major change in the sources supplying sediments to the Tuscan basins is shown to occur during this journey. Detrital zircon ages of early Cambrian to middle Ordovician metasediments mirror those of coeval northern Africa sediments: most samples were sourced in western Africa, while one sample is derived material from central northern Africa. The Tuscan block was therefore located at the peri-Gondwana margin, close to central northern Africa. The prominent mid-Ordovician magmatic arc activity (ca. 460 Ma) at the northern Gondwana margin and its detritus, characterise the zircon age distribution of Ordovician and Silurian volcano-sedimentary rocks, that were therefore generated at the northernmost Gondwana margin during subduction and subsequent initial Paleotethys rifting. The Carboniferous–Permian metasediments are dominated by populations of Ordovician and Variscan-age zircons, with a minor occurrence of Neoarchean and Paleoproterozoic zircons that is best explained by recycling of European Neoproterozoic–Cambrian metasediments. In summary, the main sources supplying the Tuscan basins were located in northern Africa throughout Cambrian–Ordovician times, shifting to the volcanic arc active at the northern Gondwana margin during the middle Ordovician. During Variscan and post-Variscan times, detrital zircon sources were mostly located in European terrains, witnessing the shift of Tuscany from Africa to Europe.

Geochemical and petrologic studies on Paleogene basanites from the Carpatho-Pannonian region (Poiana Rusca, Romania) and associated peridotite xenoliths provide information about the composition of the underlying lithosphere, the petrogenetic evolution of the magma and its mantle source, as well as the geodynamic significance of the igneous activity in a regional context. Major and trace elements as well as Sr–Nd isotopic ratios reveal an ocean–island basalt signature, interpreted as the derivation from an upper mantle source chemically similar to the European Asthenospheric Reservoir after low fraction partial melting. Due to estimated average mantle source temperatures and the absence of any subduction-related geochemical features, the igneous activity in Poiana Rusca was apparently triggered by adiabatic decompression melting, as postulated for similar and nearly coeval alkaline rocks in eastern Serbia. Differentiation processes within the Poiana Rusca magmatic suite initially resulted from removal of mainly olivine, followed by olivine + clinopyroxene fractional crystallization. The spinel-lherzolitic to harzburgitic composition of the mantle fragments point to 2–30% fractional melting at a depth of approx. 70 km. Petrographic and geochemical investigations indicate both cryptic and modal metasomatism related to the influence of both alkaline-rich silicate and alkaline-rich hydrous silicate melts rather than subduction-related fluids/melts.