Krzysztof Nejbert

Bioweathering of Kupferschiefer black shale (Fore‐Sudetic Monocline, SW Poland) by indigenous bacteria: implication for dissolution and precipitation of minerals in deep underground mine

The Upper Permian polymetallic, organic-rich Kupferschiefer black shale in the Fore-Sudetic Monocline is acknowledged to be one of the largest Cu-Ag deposits in the world. Here we report the results of the first study of bioweathering of this sedimentary rock by indigenous heterotrophic bacteria. Experiments were performed under laboratory conditions, employing both petrological and microbiological methods, which permitted the monitoring and visualization of geomicrobiological processes. The results demonstrate that bacteria play a prominent role in the weathering of black shale and in the biogeochemical cycles of elements occurring in this rock. It was shown that bacteria directly interact with black shale organic matter to produce a widespread biofilm on the Kupferschiefer shale surface. As a result of bacterial activity, the formation of pits, bioweathering of ore and rock-forming minerals, the mobilization of elements and secondary mineral precipitation were observed. The chemistry of the secondary minerals unequivocally demonstrates the mobilization of elements from minerals comprising Kupferschiefer. The redistribution of P, Al, Si, Ca, Mg, K, Fe, S, Cu and Pb was confirmed. The presence of bacterial outer membrane vesicles on the surface of black shale was observed for the first time. Biomineralization reactions occurred in both the membrane vesicles and the bacterial cells.

Dolerites of Svalbard, north-west Barents Sea Shelf: age, tectonic setting and significance for geotectonic interpretation of the High-Arctic Large Igneous Province

The dolerites of Svalbard are mineralogically and geochemically homogeneous with geochemical features typical of continental within-plate tholeiites. Their geochemistry is similar to tholeiites belonging to a bimodal suite defined as the High-Arctic Large Igneous Province (HALIP). K–Ar dating of numerous dolerites sampled from many locations across Svalbard define a narrow time span of this magmatism from 125.5±3.6 to 78.3±2.6 Mya. Discrete peaks of intensive activity occurred at 115.3, 100.8, 91.3 and 78.5 Mya corresponding to (1) breakup of the continental crust and formation of an initial rift as a result of mantle plume activity, located in the southern part of the Alpha Ridge; (2) magmatic activity related to spreading along the Alpha Ridge that led to the development of the initial oceanic crust and (3) continuation of spreading along the Alpha Ridge and termination of magmatic activity related to HALIP (last two peaks at 91.3 and 78.5 Mya).

Pilawite-(Y), Ca2(Y,Yb)2[Al4(SiO4)4O2(OH)2], a new mineral from the Piława Górna granitic pegmatite, southwestern Poland: mineralogical data, crystal structure and association

Abstract Pilawite-(Y), ideally Ca2(Y,Yb)2Al4(SiO4)4O2(OH)2, was discovered in a pegmatite near Piława Górna, Lower Silesia, Poland. The mineral occurs as white, translucent, brittle crystals up to 1.5 mm in size. It has a white streak, vitreous lustre and a hardness of 5 on Mohs scale. The calculated density is 4.007 g/cm3. Pilawite-(Y) is non-pleochroic, biaxial (+), with refractive indices α = 1.743(5), β = 1.754(5) and γ = 1.779(5), birefringence Δ = 0.03-0.04, 2Vcalc. = 65(2)° and 2Vcalc. = 68°. Pilawite-(Y) is monoclinic P21/c, with unit-cell parameters a = 8.558(3) Å, b = 7.260(3) Å, c = 11.182(6) Å, β = 90.61(4)°, V = 694.7(4) Å3. The crystal structure was refined to an R1 index of 2.76% and consists of chains of edge- and corner-sharing octahedra decorated by tetrahedra and having the stoichiometry [Al2(SiO4)4O(OH)] that link by sharing corners to form an octahedron-tetrahedron framework with large interstices that contain Ca2+ and (Y,Ln)3+. It is a graphical isomer of the Al-P framework in palermoite, Sr2Li4[Al2(PO4)2(OH)2]2. The pilawite-(Y)- bearing assemblage began crystallization at high Y + Ln activities and was modified progressively by a Ca-enriched fluid, resulting in the sequence: keiviite-(Y) → gadolinite-(Y) to hingganite-(Y) + hellandite- (Y) → pilawite-(Y) → allanite-(Y) → epidote/zoisite.

Using palaeomagnetic and isotopic data to investigate late to post-Caledonian tectonothermal processes within the Western Terrane of Svalbard

The analytical results of a total of 205 metabasic specimens from 10 palaeomagnetic sites collected from Oscar II Land in Western Spitsbergen are presented. Petrographic, structural and palaeomagnetic data all demonstrate that the pre-Caledonian ferromagnetic fabric of the metabasic rocks has been extensively reoriented and intensively remineralized. New in situ laser ablation inductively coupled plasma mass spectrometry 40Ar/39Ar age determinations suggest that the host rocks have been subject to three resetting events during the 426 – 380 Ma (Caledonian sensu lato), 377 – 326 Ma and c. 300 Ma intervals. The latter two resetting events coincide in time with the Barents Shelf-wide rift-controlled subsidence events. The derived palaeomagnetic data do not fall on the expected apparent polar wander path of Laurussia for syn- to post-Caledonian time. Consequently, four models invoking palaeogeographical great and small circle rotations, regional tectonism involving thrusting and normal listric faulting have been investigated to account for this lack of correspondence. The palaeomagnetic data do not lend support to reconstructions linking Western Svalbard with Pearya but point instead to the importance of listric faulting related to the opening of the North Atlantic Ocean that modified the geometry of the West Spitsbergen Fold and Thrust Belt. Supplementary material: (1) Field characteristics of metabasic sites, (2) detailed description of applied rock magnetic and palaeomagnetic procedures, (3) microscopic images of investigated geochronological samples, (4) in situ LA-ICP-MS 40Ar/39Ar isotopic age determination results, (5) microscopic, SEM and BSE images of investigated metabasites, and (6) anisotropy of magnetic susceptibility are available at https://doi.org/10.6084/m9.figshare.c.3673924.

Bohseite, ideally Ca4Be4Si9O24(OH)4, from the Piława GóRNA quarry, the Góry Sowie Block, SW Poland

Abstract Bohseite is an orthorhombic calcium beryllium aluminosilicate with variable Al content and an endmember formula Ca4Be4Si9O24(OH)4, that was discovered in the Piława Górna quarry in the eastern part of the Góry Sowie Block, ∼50 km southwest of Wrocław, SW Poland. It occurs in a zoned anatectic pegmatite dyke in close association with microcline, Cs-rich beryl, phenakite, helvite, ‘lepidolite’, probably bertrandite and unidentified Be-containing mica as alteration products after a primary Be mineral, probably beryl. Bohseite forms fan-like or parallel aggregates (up to 0.7 cm) of white, platy crystals (up to 2 mmlong) with characteristic striations. It is white with a white streak, is translucent and has a vitreous lustre; it does not fluoresce under ultraviolet light. The cleavage is perfect on {001} and fair on {010}, and neither parting nor twinning was observed. Bohseite is brittle with a splintery fracture and Mohs hardness is 5-6. The calculated density is 2.719 g cm-3. The indices of refraction are α = 1.579, β = 1.580, γ = 1.597, all ± 0.002; 2Vobs = 24(3)°, 2Vcalc = 27°; the optic orientation is as follows: X ^ a= 16.1°, Y ^ b = 16.1°, Z ∥ c. Bohseite shows orthorhombic diffraction symmetry, space group Cmcm, a = 23.204(6), b = 4.9442(9), c = 19.418(6) Å, V = 2227.7(4) Å3, Z = 4. The crystal structure was refined to an R1 value of 2.17% based on single-crystal data, and the chemical composition was determined by electron-microprobe analysis. Bohseite is isostructural with bavenite. Bohseite was originally approved with an end-member composition of Ca4Be3AlSi9O25(OH)3, but subsequent discovery of compositions with Be > 3.0 apfu led to redefinition of its end-member composition, holotype sample and locality, as reported here. There is extensive solid solution in bavenite-bohseite according to the scheme O(2)OH- + T(4)Si4+ + T(3)Be2+ ↔ O(2)O2- + T(4)Al3+ + T(3)Si4+, and a general formula for the bavenite-bohseite minerals may be written as Ca4BexSi9Al4-xO28-x(OH)x, where x ranges from 2-4 apfu: Ca4Be2Si9Al2O26(OH)2 (bavenite) to Ca4Be4Si9O24(OH)4 (bohseite).

Paleomagnetism and magnetic mineralogy of metabasites and granulites from Orlica-Śnieżnik Dome (Central Sudetes)

The results of palaeomagnetic, rock magnetic, and microscopic study of Early Paleozoic metabasites and granulites from the OrlicaŚnieżnik Dome (OSD, Sudetes) have been combined with geochronological data. In the eastern part of the OSD (Śnieżnik Massif, SM) ferrimagnetic pyrrhotite is prevalent, accompanied by various amounts of Fe-oxides. In the western part of the OSD (Orlica-Bystrzyca Massif, OBM) Fe-oxides dominate. All magnetic minerals originated during hydrothermal and weathering processes. The palaeomagnetic study revealed the presence of three secondary components of natural remanence: Late Carboniferous, Late Permian, and Mesozoic. Two Paleozoic components are related to volcanic activity in the Sudetes. They are carried by pyrrhotite and Fe-oxides and were isolated only in SM rocks. The Mesozoic component was determined in both parts of the OSD and is carried by Fe-oxides. It covers a time span, from ∼160 to ∼40 Ma, corresponding to a long period of alteration.

Żabińskiite, ideally Ca(Al0.5Ta0.5)(SiO4)O, a new mineral of the titanite group from the Piława Górna pegmatite, the Góry Sowie Block, southwestern Poland

Abstract 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-supergroup mineral 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)Σ=0.995(Al0.340Fe3+0:029Ti0.298V0.001Zr0.001Sn0.005Ta0.251Nb0.081)Σ=1.005[(Si0.988Al0.012)O4.946F0.047(OH)0.007)Σ=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 A1̄) 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.