Long-term evolution of Baltic Sea wave climate near a coastal segment in Poland; its drivers and impacts

The paper analyses long-term variability of wave climate near Poland for the 1958–2002 period. With spectral and cross-spectral analysis, linear regression and singular spectrum analysis the modes of long-term variability were quantified for the most energetic months (November–February). For monthly indices of North Atlantic Oscillation from 1950 until 2006, it was established that the long-term trends of NAO and significant wave height demonstrate a gentle coupling. For Januaries this relationship is strongest and dates back to 1960, for Februaries a certain consistency appears since 1975. For Novembers and Decembers no statistically discernible coupling was found. Thus, the Baltic Sea appears to be the easternmost NAO-affected region, despite its separation from the Atlantic. The hydrodynamic variability also includes a non-trivial oscillation in the January wave energy records with T=8 years. The same periodicity was identified with the multi-channel SSA technique in the long-term shoreline data of a neighboring beach. The study shows that even almost entirely isolated water bodies are becoming exposed to global climatic phenomena and accelerated erosion of sandy beaches, typical for the South Baltic region. On the other hand, the 8-year hydrodynamic cycle can be viewed as the driver of long-term shoreline evolution.     

Comparative studies of organic matter petrography of the late palaeozoic black shales from Southwestern Poland

There are at least two sapropelic units associated with Late Palaeozoic black shales in Central Europe. The older unit, of Late Carboniferous age, is the lower part of the Anthracosia Shales in the Intrasudetic Basin, and the younger one is the well-known Zechstein Kupferschiefer in both the Foresudetic Monocline and the Northsudetic Basin. The first unit is of lacustrine origin, while the second one represents deposition in a shallow marine depositional environment. Both units contain high amounts of organic matter, thus being typical black shales.The organic matter dispersed in these shales was studied petrographically. In general, the vitrinite reflectance of the shales studied indicates variable, but moderate organic matter maturity (0.68–1.25%), equivalent to the oil window. Detailed microscopic studies of the organic material dispersed in the lower unit of the Anthracosia Shales showed that liptinite, especially alginite is the most abundant component. Secondary altered organic matter, i.e. solid hydrocarbons, rarely occurs. Organic components together with mineral matter constitute a lacustrine sapropelic association, a humic (terrestrial) association and an intermediary association. The character and predominance of alginite and lacustrine sapropelic association are indicative of an open-lacustrine depositional environment. In general, this organic composition is typical of type I kerogen.Microscopic analysis of the Kupferschiefer revealed a mixture of liptinite, vitrinite and inertinite macerals, and other organic components such as amorphous sapropelic mass (ASM) and solid bitumens. The most common organic components are liptinite macerals. Bituminite and alginite predominate, and are diagnostic macerals of this unit. The amount of bituminite locally exceeds 85 vol.%. Other liptinite macerals such as sporinite and liptodetrinite, are present in significantly lower amounts, one exception being ASM, which may be present in higher amounts. Humic constituents (vitrinite and inertinite) are rare, present in small amounts in the Kupferschiefer beds. The organic matter composition points to type II kerogen for this unit.     

Space-time analysis of the relative local secular variations of the geomagnetic field (1966–2005) along the Zgorzelec-Wiżajny profile

The Zgorzelec-Wiżajny profile cuts through the main European geotectonic units of the Palaeozoic Western and Central European Platform and the East European Craton, including the connecting Trans-European Suture Zone. The paper summarises 40 years of research on geomagnetic secular variations along the Zgorzelec-Wiżajny profile since 1966. It discusses methods of processing measurement records and presenting their results. The latter are presented against the background of the local geology and the crustal deep magnetic structure data. The hitherto method of variation analysis was modified to address a new trend in the geomagnetic secular variations that has emerged in the East European Craton during the last five years (2001–2005).     

Peat-forming environments of Westphalian A coal seams from the Lower Silesian Coal Basin of SW Poland based on petrographic and palynologic data

The petrographic and palynologic compositions of coal seams of the acler formation (Upper Carboniferous, Westphalian A) from northwestern and southeastern part of the Lower Silesian Coal Basin (LSCB) were examined. Coals studied are highly volatile bituminous coal, where R_o ranges from 0.91% to 1.09%. Seam 430 from the northwestern part of the basin contains high vitrinite percentage with rather low inertinite and liptinite contents, while percentage of mineral matter is variable. This petrographic composition is associated either with a predominance of Lycospora in miospore assemblage, or with a miospore assemblage of mixed character. The abundance of Lycospora reflects vegetation composed of the arborescent lycopsids while the mixed miospore assemblage is connected with diverse palaeoplant communities, namely, arborescent lycopsids, calamites and ferns. Seams 409 and 412/413 from the southeastern part of the LSCB are rich in inertinite and liptinite, while the vitrinite content is moderate. Their characteristic feature is the occurrence of a diagnostic crassisporinite (densosporinite). Amount of the mineral components in these coals is very low. Densosporites and related crassicingulate genera are main components of these miospore assemblages and were produced by herbaceous and/or sub-arborescent lycopsids. These petrographic and palynologic features were the basis for distinguishing three maceral–miospore associations: an arborescent lycopsid and mixed associations, occurring in the seam 430 and a herbaceous and/or sub-arborescent lycopsid association which was recorded in seams 409 and 412/413. The first two assemblages are interpreted as having been deposited in a planar rheotrophic mire, whereas the herbaceous and/or sub-arborescent lycopsid association is thought to have developed in an ombrotrophic, domed mire.     

Clustering of mining-induced seismic events in equivalent dimension spaces

High energy release during seismic events induced by mining operation is one of the major dangers perturbing production in underground mines. In this work, temporal changes of seismic event parameters for one of the Rudna Mine (Poland) panels are investigated. The study aim was to find whether the temporal clustering of smaller events in different parameters can be observed before and after the high energy events (M_l?≥?3) in the mining panel. The method chosen for analysis was the study of temporal variation of fractal dimension of the seismic events parameter sets composed from: the interevent epicentral distance (dr), logarithm of seismic energy (lE), and interevent energy coefficient (dlE), which is the absolute difference between logarithms of energy of two consecutive events. Temporal variations study was performed in equivalent dimension (ED) space. The transformation of the seismic source parameters into ED space allowed to estimate and compare the temporal changes of the fractal dimension of different parameter spaces using the same method—correlation fractal dimension, and then easily compare the obtained temporal changes of fractal dimension of different parameter sets. The effect of grouping is expressed by decrease of fractal dimension, which is connected with the similarity of events parameter values. The temporal changes of the fractal dimension of seismicity before the strong induced events would indicate some initiation phase of the process leading to the high energy release. In the case of the studied Rudna Mine panel, the temporal behavior of the fractal dimension values in different parameter spaces before seismic events showed significant changes before three out of four events with CLVD dominant source mechanisms.     

Distribution of secondary minerals in crusts developed on sandstone exposures

Previous research on rock weathering crusts has revealed their large variability depending on the type of host rocks and development of weathering processes. The composition of crusts developed on natural sandstone exposures is less documented in the literature in comparison to those developed on architectonic stones. In both cases, previous research has focused mainly on the progress of salt weathering. This study considers the surfaces of sandstone tors in the Polish Outer Carpathians. The exposed parts of the rocks in this area are often covered by crust, which is up to several centimetres thick, and differs from the internal part in colour and composition. The crusts were characterized using light and electron microscopy, X‐ray diffractometry, thermal analyses, Mössbauer spectroscopy, bulk chemical analyses and sequential chemical extractions. Porosity was estimated by digital image processing. The following two hardened zones were observed: (1) thin (up to 30 µm), black, external layer, rich in carbon and composed of opal‐type silica, covered in places by sulphate incrustations and numerous spherical particles of anthropogenic origin; (2) thicker (up to several millimetres), internal part composed of a set of laminae of variable colouration, enriched in iron (oxyhydr)oxides (goethite and hematite) in comparison to the rock interior. Development of the crust results from silicon and iron redistribution during the sandstone alteration. The chief source of silica is hydrolysis of aluminosilicates, whilst that of iron is decomposition of aluminosilicates, carbonates and sulphides. Hematite is probably a result of goethite transformation. However, air pollutants may play an important role in the formation of sulphates. Silica and iron compounds affect the properties of the rock, hardening the surface and lowering porosity by formation of secondary cement. Crystallization of sulphate salts, in turn, may contribute to mechanical disintegration of the rock. Copyright © 2013 John Wiley & Sons, Ltd.     

Near surface geophysical surveys with a high frequency mutual impedance measuring system

Relationships for the mutual impedance of horizontal coplanar, vertical coplanar, perpendicular and vertical coaxial loop antenna arrays operating at a high frequency, located over a layered conducting medium, have been derived. The relationships take into account the occurrence of displacement currents in both the free space and the conducting medium. The relations can be used for calculating the earth parameters in geophysical prospecting. The use of high frequency antenna array makes it possible to determine distributions of apparent resistivity as well as apparent electrical permittivity. The potential application of the measurements of mutual impedance of loop antennas operating at a high frequency to the geophysical examinations is presented. The measuring system developed for this purpose is described. A simple method of interpreting the mutual impedance measurements to obtain the traces of apparent resistivity and apparent permittivity of the investigated earth is given.     

A study of the interaction among mining-induced seismic events in the Legnica-Głogów Copper District,Poland

We applied the Coulomb stress transfer technique to investigate interactions among seismic events induced by mining works in the Rudna mine in the Legnica-Glogów Copper District in Poland. We considered events with energy greater than 10⁵ J from the period 1993–1999. We examined the influence of the cumulative static stress changes (ΔCFF) due to previous events on the generation of subsequent ones. The results indicate that in many cases strong mining tremors produce changes in the state of stress of a sufficient magnitude to influence subsequent events. The location of over 60% of events is consistent with stress-enhanced areas where the values of ΔCFF were above 0.01 MPa. For most of the events located inside areas of a calculated negative ΔCFF, their modelled rupture zone was partially located inside stress enhanced area, providing thus additional evidence for possible triggering at the nucleation point.     

Estimation of tail dependence coefficient in rainfall accumulation fields

Extreme rainfall events are of particular importance due to their severe impacts on the economy, the environment and the society. Characterization and quantification of extremes and their spatial dependence structure may lead to a better understanding of extreme events. An important concept in statistical modeling is the tail dependence coefficient (TDC) that describes the degree of association between concurrent rainfall extremes at different locations. Accurate knowledge of the spatial characteristics of the TDC can help improve on the existing models of the occurrence probability of extreme storms. In this study, efficient estimation of the TDC in rainfall is investigated using a dense network of rain gauges located in south Louisiana, USA. The inter-gauge distances in this network range from about 1 km to 9 km. Four different nonparametric TDC estimators are implemented on samples of the rain gauge data and their advantages and disadvantages are discussed. Three averaging time-scales are considered: 1 h, 2 h and 3 h. The results indicate that a significant tail dependency may exist that cannot be ignored for realistic modeling of multivariate rainfall fields. Presence of a strong dependence among extremes contradicts with the assumption of joint normality, commonly used in hydrologic applications.