Magnetic mineralogy and paleomagnetism of serpentinized ultramafic rocks from the Braszowice-Brzeźnica fragment of sudetic paleozoic ophiolite

Complex paleomagnetic, rock-magnetic and mineralogical studies were performed on serpentinized utramafic rocks from Braszowice-Brze?nica massif (BB) situated at the southern extremity of the Niemcza Shear Zone, close to the Sudetic Marginal Fault. Studies of magnetic minerals revealed presence of several varieties of magnetite grains, and partly altered Cr-spinels. Paleomagnetic studies revealed stable component HS of natural remanence carried by magnetite formed probably during the initial serpentinization. The directions of HS have good grouping within each locality, but differ between localities. Studies of anisotropy of magnetic susceptibility (AMS) have shown that directions of anisotropy axes are steep instead of horizontal as is common within the Niemcza Shear Zone. Taking advantage of the directions of AMS we rotated the directions of HS and brought them to the reference direction for the Sudetes for 372 Ma. We suggest that after acquiring AMS and HS during the Upper Devonian, the BB became divided into multiple units due to tectonic activity in the region.     

Small angle X-ray scattering mapping and kinetics study of sub-critical CO2 sorption by two Australian coals

Time- and position-resolved synchrotron small angle X-ray scattering data were acquired from samples of two Australian coal seams: Bulli seam (Bulli 4, R_o = 1.42%, Sydney Basin), which naturally contains CO₂ and Baralaba seam (R_o = 0.67%, Bowen Basin), a potential candidate for sequestering CO₂. This experimental approach has provided unique, pore-size-specific insights into the kinetics of CO₂ sorption in the micro- and small mesopores (diameter 5 to 175 Å) and the density of the sorbed CO₂ at reservoir-like conditions of temperature and hydrostatic pressure.For both samples, at pressures above 5 bar, the density of CO₂ confined in pores was found to be uniform, with no densification in near-wall regions. In the Bulli 4 sample, CO₂ first flooded the slit pores between polyaromatic sheets. In the pore-size range analysed, the confined CO₂ density was close to that of the free CO₂. The kinetics data are too noisy for reliable quantitative analysis, but qualitatively indicate faster kinetics in mineral-matter-rich regions.In the Baralaba sample, CO₂ preferentially invaded the smallest micropores and the confined CO₂ density was up to five times that of the free CO₂. Faster CO₂ sorption kinetics was found to be correlated with higher mineral matter content but, the mineral-matter-rich regions had lower-density CO₂ confined in their pores. Remarkably, the kinetics was pore-size dependent, being faster for smaller pores.These results suggest that injection into the permeable section of an interbedded coal-clastic sequence could provide a viable combination of reasonable injectivity and high sorption capacity.     

Magnetic iron oxides occurring in chernozem soil from Ukraine and Poland as indicators of pedogenic processes

The paper concerns the complex study of pedogenic and magnetic characteristics of unpolluted soil profiles from Ukraine (3 profiles, of which two represent chernozem and one kastanozem) and Poland (1 profile of chernozem), all with loess parent material. Two of the profiles were situated further south than the other two. The “southern” zone is characterized by lower precipitation rate and higher annual temperatures than the “northern” zone. Depth variations of magnetic properties obtained with various methods were compared with pedogenic characteristics. The common characteristic of all profiles is enhancement of susceptibility in their upper parts related to the presence of superparamagnetic/ single-domain grains of maghemite/oxidized magnetite of pedogenic origin. However, variations of magnetic characteristics measured down depth profiles differ between profiles probably due to differences in climatic conditions and, perhaps, parent loess.     

OSL‐based chronostratigraphy of river terraces in mountainous areas,Dunajec basin,West Carpathians: a revision of the climatostratigraphical approach

The technique of optically stimulated luminescence (OSL) dating applied to fluvial sediments provided a geochronological framework of river terrace formation in the middle part of the Dunajec River basin – a reference area for studies of evolution of river valleys in the northern part of the Carpathians (West Carpathians). Fluvial sediments at 18–90 m above valley bottoms were dated in the valleys of the Dunajec River and one of its tributaries. The resulting ages range from 158.9±8.3 to 12.2±1.3 ka. This indicates that some of the terrace sediments were deposited much later than previously assumed on the grounds of a combined morphostratigraphical and climatostratigraphical approach. The OSL‐based chronostratigraphy of terrace formation consists of seven separate phases of fluvial aggradation, separated by periods of incision and lateral erosion. Some of the ages determined correspond to warm stages of the Pleistocene – Marine Isotope Stage 3 (MIS 3) and MIS 5 – demonstrating that some terraces were formed during interstadial or interglacial periods. The results provide a key for evaluating rates of neotectonic uplift, allowing us to decipher the response of a fluvial system to climate change within the context of the glacial–interglacial scheme.     

Stable 18O and 13C isotope records of Viviparus diluvianus (Kunth, 1865) shells from Holsteinian (MIS 11) lakes of eastern Poland as palaeoenvironmental and palaeoclimatic proxies

The oxygen and carbon stable isotope composition of Viviparus diluvianus shells was determined in the palaeolakes of the Holsteinian interglacial (MIS 11) in eastern Poland: the Ortel Królewski, Hrud, Ossówka, Roskosz and Szymanowo lakes. The occurrence of V. diluvianus covers the Taxus zone, the so‐called intra‐interglacial cooling period (Pinus‐Larix zone), the climatic optimum (Carpinus‐Abies zone) and the post‐optimal period with an undefined pollen zone. The isotope record of V. diluvianus shells allowed palaeoclimate and palaeoenvironmental reconstructions. δ¹⁸O and δ¹³C vary from −8.7‰ in the post‐optimal period to −4.8‰ in the optimal period, and from −10.6‰ at the beginning of the Taxus zone to −4.2‰ at the climatic optimum, respectively. A positive correlation of the isotope curves indicates closed‐water bodies, and only at Roskosz was some occasional overflow inferred. Higher oxygen isotopes correspond to an increase in temperature and/or enhanced evaporation, which is well marked in the Carpinus‐Abies zone, whereas samples enriched in ¹³C are correlated with periods demonstrating a lower water level and higher productivity in the lakes. Episodes of lake shallowing and dense aquatic vegetation occurred in the Pinus‐Larix zone and during the climatic optimum. The isotope ratios for the climatic optimum significantly exceed those of the other periods, thus pointing to warmer conditions. An estimation of relative changes of average summer temperatures using the δ¹⁸O/temperature gradient yielded variation of 1–2 °C within the lakes. Absolute temperature reconstructions indicate the effects of specific local conditions. Hence, V. diluvianus shells offer a reliable proxy in qualitative studies of interglacial lake records.     

Distortion of the spectrum of the microwave background radiation in an anisotropic universe

Distortion of spectrum of the cosmic microwave background due to anisotropic expansion is discussed. We consider an anisotropic cosmological model with a secondary re-heating and re-ionization. After the secondary re-heating distribution of photons momenta becomes isotropic but the spectrum becomes slightly different from that of black body.     

Evolution of close binaries and origin of Algol-type systems

The evolution of close binary systems was followed for ten systems with the initial mass of the primary in the range 1–4M and with different initial mass ratios and initial separations. A brief discussion of the evolution of the contact component is presented for two separate cases: when the primary reaches its Roche lobe during central hydrogen burning (case A) and after the exhaustion of hydrogen in the center (case B).The models obtained are compared with observed semi-detached systems separately for massive (with total mass greater than 5M ) and low mass (with total mass below 4M ) binaries. It is shown that the contact components of the observed massive binaries are probably burning hydrogen in the core. On the contrary, the majority of contact components of the observed low-mass binaries are burning hydrogen in the shell. The observed distribution of such binaries as a function of different luminosity excesses of contact components seems to indicate that their origin is connected with case A rather than with case B.     

Variation of certain parameters of regional stress tensor under condition of rockburst hazard

The feasibility of gaining valuable geomechanical information derived from seismological data and its specialist interpretation for utilisation in the area of assessing hazards due to mining tremors and rockbursts has become a development of signal importance in mining seismology. Undoubtedly of particular interest is a certain knowledge of the directions of the principal stresses ₁, ₂, ₃ of the regional stress tensor. For their determination, use is made of a set of parameters from the mining tremors' regional focal mechanism solutions (angular parameters of nodal planes and axes of principal stresses in the tremor focus —P andT). Results of research conducted at the Szombierki and Wujek mines and analysis of calculated results for parameters of regional stress tensor show that there exist appreciable differences between values of these parameters and also a clear correlation with local extraction conditions that is of significance from the point of view of seismic hazard.