Precise U–Pb zircon dating using the chemical abrasion – isotope dilution – thermal ionization mass spectrometry (CA-ID-TIMS) method constrains the age of the Central Sudetic Ophiolite (CSO) in the Variscan Belt of Europe. A felsic gabbro from the Ślęża Massif contains zircon xenocrysts dated at 404.8 ± 0.3 Ma and younger crystals dated at 402.6 ± 0.2 Ma that determine the final crystallization age of the gabbro. An identical age of 402.7 ± 0.3 Ma was determined for plagiogranite from the Nowa Ruda–Słupiec Massif, and plagiogranite from the Braszowice–Brzeźnica Massif yields a similar, but less reliable, age of > 401.2 Ma. The different massifs in the CSO are therefore considered as tectonically dismembered fragments of a single oceanic domain formed at c. 402.6–402.7 Ma (Early Devonian – Emsian). The magmatic activity recorded in the CSO was contemporaneous with the high-temperature/high-pressure metamorphism of granulites and peridotites in the Góry Sowie Massif, separating dismembered parts of the CSO. This suggests geodynamic coupling between the continental subduction recorded in the Góry Sowie and the oceanic spreading recorded in the CSO. Regional geological data indicate that the CSO was obducted before c. 383 Ma, less than 20 Ma after its formation at an oceanic spreading centre. The CSO is shown to be one of the oldest and first obducted among the Devonian ophiolites of the Variscan Belt. The CSO probably originated in an evolved back-arc basin in which the influence of subduction-related fluids and melts increased with time, from negligible during the formation of predominant mid-ocean-ridge-type magmatic rocks to strong at later stages, when rodingites, epidosites and other minor lithologies formed.

Sodic pyroxene is reported from an Ordovician metatrachyte of the Kaczawa Mountains, SW Poland. Its composition ranges from Jd0.98Ae0.02 to Jd0.15Ae0.85. Relict jadeite and phengite (up to 3.75 Si atoms per fomula unit) belong to the peak-pressure assemblage of an early HP-LT event. Later greenschist-facies stages are represented by riebeckite, biotite, chlorite, low-Si potassic white mica and actinolite. P-T pseudosections calculated for the range 200–450°C, 3–13 kbar allow evaluation of the conditions of formation of jadeite in the metatrachyte and derivaton of a P-T path. Considering the position of prograde, peak and retrograde metamorphic assemblages and respective mineral compositions, we can derive the following equilibration stages: 8.5±0.5 kbar, 270±20°C for the pressure maximum, 6.0±1.0 kbar, 310±20°C for the temperature maximum and 3.5±0.5 kbar, 280±20°C as well as <3.5 kbar, <280°C for the retrograde stages.

The metamorphic gradient for the peak-pressure is estimated at ∼10°C/km, which is typical of a subduction setting involving subducted continental crust, in particular of an exhumation channel within a collision zone of a microplate. Based on earlier structural observations, the ESE-oriented subduction in the NE Bohemian Massif was confined with WNW thrusting and followed by extension and ESE backward normal faulting during Devonian–Early Carboniferous times.

Maneckiite, ideally NaCa2Fe22þ (Fe3+Mg)Mn2(PO4)6(H2O)2, was found in a pegmatite at Michałkowa, Góry Sowie Block, SW Poland. The mineral forms subhedral and anhedral crystals ~150 μm × 150 μm in the outer zone of phosphate nodules, where it is associated with fluorapatite, wolfeite, Ca-rich graftonite and alluaudite-group minerals. Maneckiite is transparent, dark brown, with a colourless streak and vitreous lustre, brittle, and has a good cleavage // {010}, a splintery fracture and a Mohs hardness of ~5. The calculated density is 3.531 g cm–3. Maneckiite is pleochroic: α = dark green, β = dark blue/green, γ = light brown/tan, biaxial (+) with refractive indices α = 1.698(2), β = 1.706(2), γ = 1.727(2) and birefringence Δ = ~0.03; 2Vmeas. = 65.9 (1.5)° and 2Vcalc. = 64°, dispersion is obscured by the dark colour, and optical orientation X//a, Y//b, Z//c. Maneckite is orthorhombic (Pcab) and has unit-cell parameters a = 12.526(4) Å, b = 12.914(5) Å, c = 11.664(4) Å and V = 1886.8(5) Å3. The strongest reflections are (dhkl in Å; I; hkl): 2.759, 100, 402; 2.916, 78, 004; 3.020, 68, 401; 2.844, 35, 014; 2.869, 31, 240; 2.825, 30, 042. Maneckiite has the wicksite structure and is its M(3)Mn-analogue. The mineral crystallized as a product of Na- and Ca-metasomatism induced by a HT fluid in the presence of Al3+ from a neighbouring aluminosilicate melt. A Gladstone-Dale index, 0.027, places maneckiite in the category ‘excellent’.

Żabińskiite, ideally Ca(Al0.5Ta0.5)(SiO4)O, was found in a Variscan granitic pegmatite at Piława Górna, Lower Silesia, SW Poland. The mineral occurs along with (Al,Ta,Nb)- and (Al,F)-bearing titanites, a pyrochlore-supergroupmineral and a K-mica in compositionally inhomogeneous aggregates, ∼120 μm × 70 μm in size, in a fractured crystal of zircon intergrown with polycrase-(Y) and euxenite-(Y). Żabińskiite is transparent, brittle, brownish, with a white streak, vitreous lustre and a Mohs hardness of ∼5. The calculated density for the refined crystal is equal to 3.897 g cm–3, but depends strongly on composition. The mineral is non-pleochroic, biaxial (–), with mean refractive indices ≥1.89. The (Al,Ta,Nb)-richest żabińskiite crystal,(Ca0.980Na0.015)∑=0.995(Al0.340Fe3+0.029Ti0.298V0.001Zr0.001Sn0.005Ta0.251Nb0.081)∑=1.005[(Si0.988Al0.012)O4.946F0.047(OH)0.007)∑=5.000];60.7 mol.% Ca[Al0.5(Ta,Nb)0.5](SiO4)O; is close in composition to previously described synthetic material. Żabińskiite is triclinic (space group symmetry A1) and has unit-cell parameters a = 7.031(2) Å, b = 8.692(2) Å,c = 6.561(2) Å, α = 89.712(11)°, β = 113.830(13)°, γ = 90.352(12)° and V = 366.77 (11) Å3. It is isostructural with triclinic titanite and bond-topologically identical with titanite and other minerals of the titanite group.Żabińskiite crystallized along with (Al,Ta,Nb)-bearing titanites at increasing Ti and Nb, and decreasing Ta activities, almost coevally with polycrase-(Y) and euxenite-(Y) from Ca-contaminated fluxed melts or early hydrothermal fluids.

The tectonized and metamorphosed mudrocks within the Variscan accretionary prism of the Kaczawa Mountains in SW Poland comprise sedimentary mélanges together with more coherent stratigraphic units; some represent large olistoliths deposited in a submarine trench. We infer a trend of progressive near-surface stratal disruption in mud-dominated deposits due to dewatering that forms a continuum with subduction-related tectonic structures imposed on unconsolidated sediment during deeper burial. The assemblage of characters suggests that an accretionary prism environment can influence, and leave characteristic traces of, the total burial history of a trench succession.

Seven granitoid gneisses from the contact zone between the eastern margin of the Variscan belt and the Brunian microcontinent in SW Poland have been dated by ion-microprobe and 207Pb/206Pb single zircon evaporation methods. The zircons define two age groups for the gneiss protoliths: (1) late Neoproterozoic c. 576–560 Ma and (2) early Palaeozoic c. 488–503 Ma granites. The granitoid gneisses belonging to the basement of the Brunian microcontinent contain abundant Mesoproterozoic to latest Palaeoproterozoic inherited material in the range of 1200–1750 Ma. The gneisses of the Variscan crustal domain lack Mesoproterozoic inherited zircon cores. Trace element geochemistry of Proterozoic gneisses reveals features resembling either volcanic arc or post-collisional granites. The studied rocks are geochemically similar to other Proterozoic orthogneisses derived from the basement of the Brunian microcontinent. Gneisses with early Palaeozoic protolith ages are geochemically comparable to granitoid gneisses widespread in the adjacent Sudetic part of the Bohemian Massif and are considered characteristic of peri-Gondwanan crust. Our data prove the dissimilarity between the Brunia plate and the westerly terranes of the Variscan belt. The occurrence of granitic gneisses with late Neoproterozoic protolith ages and widespread Mesoproterozoic inheritance in our dated samples support an East Avalonian affinity for the Brunian microcontinent. In contrast, the abundance of gneisses derived from an early Palaeozoic granitic protolith and devoid of Mesoproterozoic zircon cores supports the Armorican affinity of the Variscan domain bordering on the Brunia plate from the west. Structural evidence shows that the eastern segment of the Variscan belt is juxtaposed against the Brunian microcontinent along a N–S-trending tectonic contact, possibly equivalent to the Rheic suture.

The large Variscan Karkonosze Granite in the West Sudetes, representative of the vast Variscan granite plutonism in Central Europe and located adjacent to regional tectonic suture and strike-slip-zones, has been difficult to date precisely; a range of published data varies between c. 304 and 328 Ma. However, the granite is cut by locally numerous lamprophyre and other dykes. Dating of the dyke rocks, emplaced shortly after the granite intrusion and cooled more rapidly, provides a promising tool for the verification of published SHRIMP results on the granite itself. SHRIMP zircon geochronology of a studied micromonzodiorite dyke indicates substantial admixture of inherited zircons of c. 2.0, 1.4 Ga (207Pb–206Pb minimum ages), and c. 570 (and 500?) Ma. The average concordia age of the main magmatic population of the zircons in the dyke is 313 ± 3 Ma (2σ); however, the true magmatic age might be older, around 318 Ma. This would constrain the age of the hypabyssal magmatism in the Karkonosze Massif and the minimum age of the host Karkonosze Granite. Thus, the Karkonosze Granite is confirmed as representative of an early phase of Variscan granite plutonic activity in the central-European Variscides.

SIMS dating of detrital zircons from the stratigraphically enigmatic Radzimowice Slates of the Kaczawa Mountains (Sudetes, SW Poland), near the eastern termination of the European Variscides, has yielded age populations of: (1) 493–512 Ma, corresponding to late Cambrian to early Ordovician magmatism and constraining a maximum depositional age; (2) between 550 and 650 Ma, reflecting input from diverse Cadomian sources; and (3) older inherited components ranging to c. 3.3 Ga, with age spectra similar to those from Gondwanan North Africa. The new data show that the Radzimowice Slates cannot form a Proterozoic base to the Kaczawa Mountains succession, as suggested by earlier models, but was deposited, at the earliest, as an extensional basin-fill, during a relatively late stage of the break-up of this part of northern Gondwana.