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Emission Measurements of Geogenic Greenhouse Gases in the Area of “Pusty Las” Abandoned Oilfield (Polish Outer Carpathians)

Guzy P., Pietrzycki D., Świerczewska A., Sechman H., Twaróg A., Góra A.

Journal of Ecological Engineering

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2017

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Vol. 18, nr 4

100--109

EN

The Carpathians may play a significant role as a supplier of greenhouse gases to the atmosphere. Unfortunately, most of the discovered oil and gas deposits are recently only historical objects. An example is the Sękowa-Ropica Górna-Siary oil deposit located in the marginal part of the Magura Nappe where oil had been extracted in dug wells until the mid XX century. One of such extraction sites is the “Pusty Las” oilfield. In that area, 10 methane and carbon dioxide emission measurement sites were located, among which 4 in dried dug wells and 6 in dig wells still filled with oil and/or water. Dynamics of methane and carbon dioxide concentration changes were measured with the modified static chambers method. Gas samples were collected immediately after the installation of the chamber and again, after 5 and 10 minutes. In the case of reclaimed or dry dug wells, static chamber was installed directly at the ground surface. In wells still filled with oil and/or water the chamber was equipped with an “apron” mounted on special sticks. The dynamics of concentrations changes varied from -0.871 to 119.924 ppm∙min-1 for methane and from -0.005 to 0.053% obj∙min-1 for carbon dioxide. Average methane emission was 1.9 g∙m-2∙d-1 and that of carbon dioxide was 26.95 g∙-2∙d-1. The measurements revealed that an abandoned oil field supplies significant amounts of greenhouse gases to the atmosphere although the emission of methane is lower than that measured e.g. in mud volcanoes located in various parts of the world.

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Department of Fossil Fuels

Świerczewska A., Górecki W.

Geology, Geophysics and Environment

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2016

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Vol. 42, no. 2

231--235

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Significance of pressure solution structures analysis for fluid flow studies – examples from Struga-1 well (Zechstein Main Dolomite; W Poland): first results

Górka J., Świerczewska A., Krzyżak A.

Geology, Geophysics and Environment

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2015

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Vol. 41, no. 1

82--83

EN

The internal structure and composition of pressure solution structures are factors that may influence petroleum generation and migration (Hofmann & Leythaeuser 1995). Pressure solution structures (PSS) i.e. stylolites and solution seams occur frequently in Zechstein carbonates of Poland (Kłapciński 1972). They are common in rocks of the Zechstein Main Dolomite. These rocks are both the source and reservoir rocks (Kotarba et al. 2000). Therefore, defining the role of pressure solution structures in migration of hydrocarbons is a key element of reservoir characterization.The main aim of this study is to determine the role of pressure solution structures in fluid flow in dolomites from the Polish part of the Zechstein Main Dolomite (Ca2). Sixteen samples were collected from the core of the Struga-1 well for mineralogical, microstructural and petrophysical studies. The inflow of oil was obtained from the interval within the range of 2042.5–2058.5 meters (Kotarba et al. 2000). This interval was sampled and it corresponds to an occurrence of carbonates of the Zechstein Main Dolomite. Lithology of the sampled cored interval was described based on macroscopic studies. Standard thin sections were studied using polarization microscopy for identification of mineral composition and microstructures. These studies were supplemented by observations in UV light for identification of organic matter and hydrocarbon inclusions. Chemical staining method was used in identification of carbonate minerals in 6 thin sections by solution of alizarin red and potassium ferricyanide. All thin sections were observed under the cathodoluminescence (CL). PSS were studied in details using the scanning electron microscopy (SEM) with X-ray microanalysis (EDS). Frequency of their occurrence in the core was described by macroscopic and microscopic studies as number of PSS per 1 m and per 1 cm respectively. Nuclear magnetic resonance (NMR) was used to define the value of porosity. These measurements were performed on eight water-saturated samples using the 2MHz Magritek Rock Core and 24MHz Tomography system. The pore size distribution (PSD) of the rock sample was precisely determined by T2CMPG experiments. According to the paleogeographic interpretation of Ca2 basin Struga-1 well is located in a platform depression (flat) (comp. Kotarba et al. 2000). This was a low-energy zone dominated by mudstones, wackestones with numerous bioclasts, e.g. gastropodes, foraminifers and bivalves. Intraclasts were delivered from adjacent high-energy zones (Czekański at al. 2010). In a new interpretation by Kosakowski & Krajewski (2013) the well intersects facies association of the carbonate platform lower slope. The studied rocks are fine crystalline dolomites. Coarser crystals occur only at the lowest part of the studied core. In most of thin sections primary textures are not recognized. In some samples bioclasts replaced by dolomite as well as anhydrite and gypsum are visible. Under the CL the dolomite mosaics show dark orange to brown luminescence. Relicts of calcite are absent or very rare. Anhydrite is observed as patches filling pore spaces. Moldic and intercrystalline porosity is present. Moldic porosity is probably related to dissolution of bioclasts and halite crystals. A few vertical microfractures were noted. Some of them are filled by dolomite, blocky anhydrite, and gypsum and fluorite crystals. However, some microfractures are still open and filled in part by drusy anhydrite and/or gypsum crystals. The effective porosity of dolomite samples varies from 1.59% to 2.69%. Solution seams are horizontally oriented. Their thickness is up to 0.1 mm. Some of the seams form clusters up to 1 mm t hick . In thin sections number of solution seams varies from 0/cm to 8/cm. Dark thicker seams are also visible on the core. They are most frequent in t he middle par t of t he core profile (up to 200/m). Two groups of stylolites are noted: vertically and horizontally oriented. Microscopic studies concerned only horizontal, diagenetic structures. Amplitude of them is diverse reaching 1.2 cm. They occur mostly in the lowest part of the core profile where solution seams are rare. Fluorescence microscopy of polished sections revealed a presence of organic matter. Dark brown to black organic laminae and orange oil inclusions are present inside PSS. Framboidal pyrite was recognized bot h in dolomite and solution seams. Clay minerals are common in solution seams. Based on SEM-EDS analyses fluorite was recognized along stylolites.Thin wavy microfractures are associated with PSS. These microfractures are short (i.e. up to 1 mm), less than 0.01 mm thick. They are oriented parallel to PSS. Relationship between porosity values and quantity of PSS is unclear. Maybe observed microfractures reflect stress anisotropy in the clay seam and stylolite. Summing up, PSS have recorded migration of oil as well as migration of other fluids, which were responsible for fluorite mineralization. Organic matter accumulation in stylolites and solution seams of carbonate rocks was documented among others by Leythaeuser (1995). In the studied rocks, this accumulation is marked by an occurrence of dark laminae probably overmature organic matter. The presented results show that PSS hosted in dolomites from Struga-1 well impacted redistribution of organic matter and migration of fluids.

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Identification of tectonic microstructures in flysch sandstones of the Outer Carpathians using X-ray nanotomography and nuclear magnetic resonance – first results

Radzik N., Świerczewska A., Krzyżak A.

Geology, Geophysics and Environment

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2015

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Vol. 41, no. 1

127--128

EN

Deformation bands and microfractures occurring in sandstones affect the petrophysical properties of the rock and determine fluid flow. Deformation bands are quasi-tabular structures, up to 5 mm thick that accommodate offsets on the order of a few centimeters (Fossen 2010). Such bands show different petrophysical properties in relation to the surrounding rocks and may function as either a path or a barrier to the migrating fluids (Antonellini et al. 1994, Fossen 2010). High porosity rocks show commonly low permeability due to the presence of deformation bands. Recognition of such relationships is important in petroleum geology, particularly for proper reservoir characterization (e.g. Fossen et al. 2007, Ballas et al. 2012, 2013). The aim of the study is to identify and to characterize deformation bands occurring in flysch sandstones of the Outer Carpathians using X-ray nanotomography and nuclear magnetic resonance (NMR). Moreover, the impact of sample size on obtained results was also studied. For this study, samples of medium-grained arenites showing catalclastic deformation bands have been collected from the lower Krosno Beds of the Silesian Nappe. Permeability of the studied samples measured along deformation bands and in perpendicular direction varies significantly, being 0.13 mD and <0.001 mD, respectively. Analyses were conducted using X-ray nanotomography Nanotom S General Electric. The recorded data were processed and analyzed using ImageJ and myVGL software. The NMR measurements were carried out on water-saturated samples using the 2MHz Magritek Rock Core Analyzer and 24MHz Tomography System. The pore size distribution (PSD) of the rock sample was determined precisely by T2CMPG experiments. The spatial estimation of the deformation bands achieved from T2 spatially resolved measurements. Complementary data regarding to band geometry was registered using three-dimensional Single Point Imaging (SPI) (comp. Zhang & Blümich 2014). Cylindrical plugs38 mm high and 25 mm in diameter were analysed. The same plugs were used for permeability measurements. The X-ray nanotomography measurements were carried out in three resolutions. The first measurement was carried out with a resolution of 4.2 microns, but the resultant images were difficult to interpret. Therefore, successive analyses were performed with a resolution of 20 microns covering the entire volume of the samples. After locating microstructures samples were X-rayed again with a resolution of 2.1 microns. In sections obtained at a resolution of 4.2 microns, fine structure attributable to deformation band reveals parallel grain orientation and higher density compared with the host sandstone. We observed a slight offset along deformation bands. Three-dimensional image of the sample obtained at a resolution of 20 microns determined the geometry of tectonic microstructures. In one of samples, two structures were recognized. One of them was oriented parallel to the axis of the core, the other was inclined at an angle of about 60 degrees. The thickness of deformation band visible in the cylindrical plug was much larger (2 mm) than the thickness of the surface obtained by visualization. This was due to the presence of microfractures, which formed along the deformation band. Measurement with a resolution of 2.1 microns took an upper base of the cylindrical plug. Two thin fractures and one relatively thick fracture (approx. 0.2 mm) were distinguished. This indicates that the deformation band visible on the surface of the core passes into the microfracture within the sample. It was also confirmed by the visualization with a resolution of 20 microns. Determination of porosity and permeability of the sandstone using the X-ray nanotomograph was impossible due to small pore size that the device is not able to register. However, visualization made with a resolution of 20 microns allowed to clarify the reasons for the different measurements of permeability. Increase of the permeability in the direction parallel to the axis of the core is caused by the presence of open microfractures. The NMR results confirmed possibility to visualize geometry of the bands and their influence for the spatial distribution of porosity. The results show that too large sample sizes make impossible to perform the analysis with high resolution. According to Rodrigues et al. (2015) sample dimensions of 15 × 10 × 10 mm are sufficient to determine the porosity of deformation bands. Published results on three-dimensional micro-tomography of deformation bands concern aeolian sandstones showing high mineralogical and textural maturity (Rodrigues et al. 2015). In contrast, studied flysch sandstones show large diversity of their mineral composition. Therefore, visualization of microtectonic deformation hosted in these sandstones is more difficult to interpret.

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K-Ar dating of bentonite diagenesis in accretionary-wedge turbidites : case study from Western Outer Carpathians

Świerczewska A., Paul Z., Banaś M., Tokarski A. K.

Annales Societatis Geologorum Poloniae

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2015

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Vol. 85, No. 1

177--185

EN

Sixteen bentonite layers of Eocene–Oligocene age were sampled at thirteen sites in accretionary-wedge turbidite sequences, in the three innermost nappes of the Western Outer Carpathians. K-Ar dating was carried out for five of these layers to obtain the maximum burial ages. All of the ages obtained are older than the stratigraphic ages of the host strata. This relationship is due to significant contamination of the bentonites with non-authigenic minerals. This contamination resulted from rapid sedimentation during synsedimentary folding, which is a common feature in accretionary wedges. It follows that the K-Ar dating of bentonite layers in the turbidite sequences of accretionary wedges should be largely restricted to the very distal facies of turbidites or to pelitic intercalations within the turbidites.

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Correlation between organic and inorganic indicators of thermal maturity in Dukla Nappe (Polish Outer Carpathians)

Waliczek M., Więcław D., Świerczewska A.

Geology, Geophysics and Environment

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2014

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Vol. 40, no. 1

137--138

EN

Correlation between organic (vitrinite reflectance (Ro) and Rock-Eval Tmax temperature) and inorganic (mixed layer illite/smectite (I/S)) indicators of thermal maturity depend mainly on the maximum temperature achieved by the rock and the time exposure of this temperature. During sedimentary or tectonic burial of rocks, clay minerals may react diversely to organic matter due to heat flow features and the duration of heating (Aldega et al. 2005). The aim of this study was to correlate maximum paleotemperatures of the Oligocene Menilite Shales from the Polish Outer Carpathians determined based on vitrinite reflectance and Rock-Eval pyrolysis data to those calculated using I/S ratio. The analysis was performed on eight claystone samples collected from natural exposures of the Dukla Nappe. Four of them were taken in tectonic windows within the Magura Nappe: Świątkowa and Grybów tectonic windows. All samples were analyzed by vitrinite reflectance, Rock-Eval and smectite to illite conversion. Reflectance of vitrinite and huminite macerals was measured under oil immersion using Carl Zeiss Axioplan microscope in reflected white and blue (fluorescence) light. Standard deviation was calculated for all measurements. The values of Ro were converted into paleotemperatures according to Barker & Pawlewicz (1986). The degree of smectite to illite conversion is shown as the percentage of smectite (%S) in I/S. To define this percentage X-ray powder diffraction was used (Dudek & Środoń 1996 and references therein). Maximum paleotemperatures were estimated according to Sucha et al. (1993). Rock-Eval pyrolysis was conducted on Delsi Instruments apparatus equipped in TOC module to determine: a) total organic carbon content (TOC), b) the amount of residual hydrocarbons generated during pyrolysis of organic matter (S2) and the temperature of maximum of S2 peak (Tmax). The Rock-Eval data indicate that the analysed samples are rich in organic matter, predominantly of oil-prone Type II kerogen. Values of Tmax vary from 421C to 453°C, and were re-calculated into vitrinite reflectance values using equation proposed by Jarvie et al. (2005) and then into paleotemperatures indicating range between 42-153°C. The Ro values vary between 0.45-1.0% indicating paleotemperatures between 51-154°C. The analyzed rocks contain 12-40% S in I/S suggesting paleotemperatures between 104-176°C. Usually, paleotemperatures determined from I/S are higher than those achieved using organic indicators. bIn both, present and previous (Waliczek & Więcław 2013) studies, a strong positive correlation between organic maturity indicators was observed. The good correlation between the organic and inorganic paleotemperature indicators was noticed for all samples collected from tectonic windows of the Dukla Nappe, where organic matter is mature (above 0.7% in Ro scale). For samples containing immature or early-mature organic matter maximum paleotemperatures calculated from I/S data are 40-70°C higher than those calculated based on results of organic matter investigations. The higher maturation of samples from tectonic windows than those from the Dukla Nappe are probably related to the overburden of these rocks by the Magura Nappe. Illitization process is probably time-independent (Pollastro 1993, Środoń 1995) whereas vitrinite reflectance stabilizes in normal burial coalification after about 106-107 years (Barker 1989). The good positive correlation between the organic and inorganic paleotemperature indicators occurs only for samples from tectonic windows which might lead to the conclusion that these sediments were temperature-affected by at least 106 years.

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Pierwsze stanowisko holoceńskich uskoków w polskich Karpatach zewnętrznych

Zuchiewicz W., Tokarski A. K., Świerczewska A., Zasadni J., Siemińska A.

Przegląd Geologiczny

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2011

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Vol. 59, nr 8

566-575

EN

The paper presents the first example of Holocene faults in the OuterWestern Carpathians in Poland. Small-scale normal faults at Koninki, Gorce Mts., cut both Palaeocene strata of the Ropianka Formation of the Magura Nappe and overlying coarse-clastic bedload facies of Holocene alluvium that builds a 5-5.5-high terrace step of a small valley. These NE-trending faults are accompanied by reorientation of clast a-b planes subparallel to fault planes and by clast fracturing. Such deformations must have been induced by relatively strong earthquakes, unknown from historical record of the Outer Carpathian seismicity. Fault attitude points to NW-oriented axis of the minimum principal stress, which is compatible with parameters of the present-day stress field in the Outer Western Carpathians of Poland.

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Neotectonic activity of the Skawa River Fault Zone (Quter Carpathians, Poland)

Zuchiewicz W., Tokarski A. K., Świerczewska A., Cuong N. Q.

Annales Societatis Geologorum Poloniae

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2009

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Vol. 79, No 1

67-93

EN

The Skawa River catchment basin in the Outer Western Carpathians of Poland is situated upon morphostructures showing differentiated mobility in the Quaternary. Long profile of river channel reveals the lowest values of concavity index among the Polish Outer Carpathian rivers, pointing to low degree of river profile maturity, particularly in its middle reach coinciding with a zone of abnormally high river bed gradients. The Skawa River valley utilizes in its middle and northern reaches the Skawa River Fault Zone (SRFZ) composed of differently oriented oblique-slip faults, visible on DEM images as well-marked, rectilinear topolinea-ments. The NNW–SSE to N-S faults in the Silesian Nappe were probably reactivated in Late Pleistocene times as normal faults downthrowing their eastern sides, as shown by abnormally high position of the Weichselian Early Glacial straths on the western valley side. Such an episode of neotectonic activity (late Early Glacial times of the Last Glacial stage) has not been recognized so far in the other river valleys of the Polish segments of the Western Outer Carpathians. We conclude that some of the NNW-SSE to N–S trending faults were reactivated as strike-slip faults. This would conform to the present day stress arrangement within the Polish segment of Carpathians. Moreover, deformations of the Pleistocene straths between Osielec in the south and Wadowice-Zator areas in the north appear to indicate both pre-Weichselian and Weichselian reactivation of the Silesian and - to a lesser extent - Magura frontal thrusts. These movements continued also in the Holocene, although to a smaller extent, most probably due to moderately strong and/or strong earthquakes of magnitudes exceeding 5.5-5.7, resulting in clast fracturing within Holocene alluvium, particularly strong on the Silesian frontal thrust, and less intensive on the Carpathian marginal and Magura frontal thrusts, as well as on some faults that belong to the SRFZ. We are convinced that the record of seismically-induced clast fracturing on one of major fault zones in the Outer Carpathians should lead to revision of the hitherto-existing seismic risk assessment of this region, and particularly of the city of Kraków and other urbanized areas, as well as the planned artificial water reservoir at Świnna Poręba.

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Fractured clasts in neotectonic reconstructions: an example from the Nowy Sącz basin, western outer Carpathians, Poland

Tokarski A.K., Świerczewska A., Zuchiewicz W.

Studia Quaternaria

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2007

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Vol. 24

47-52

EN

This paper presents the results of a detailed analysis of fractured clasts hosted within Miocene and Pleistocene paraconglomerates that are exposed close to a map-scale overthrust. Both these paraconglomerates bear numerous fractured clasts (22-50%). The architecture of fractures (joints and minor faults) is well-organized and independent of both clast orientation and the degree of clast roundness. The fractures were formed in situ, most probably due to neotectonic activity of the map-scale overthrust. The number of fractured clasts is positively correlated with the clast size, and negatively correlated with the grain-size of clasts of detrital rocks. The number of fractured clasts increases in clasts of detrital rocks, compared to those of quartzites and magmatic rocks.

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Tarasy rzeczne Nysy Kłodzkiej oraz drobne plejstoceńskie struktury tektoniczne w strefie sudeckiego uskoku brzeżnego i przełomu bardzkiego w Janowcu

Badura J., Przybylski B., Tokarski A., Świerczewska A.

Przegląd Geologiczny

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2007

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Vol. 55, nr 3

228-228

EN

New research in the N part of the Bardo Gorge [close to the Sudetic Marginal Fault] evidenced the occurrence of two hitherto unknown Pleistocene river terraces. The terraces were interpreted basing on digital elevation model [DEM] 1;10,000 and radars sweeping of the Earth’s surfaces [DETM level 2]. Moreover, the results of petrographical analysis of deposits exposed in the 22 high river terrace show two-tier structure of the terrace. This suggest a polygenetic age of the terrace. Within the last terrace fractured clasts and small-scale faults were observed. Fractured clasts were studied in the bottom part of the 22-m-high river terrace where numerous fractured clasts occur. This part of the terrace is composed of gravels containing clasts up to 80 cm across. The matrix is sandy-clayey. The fractures are usually restricted to particular clasts. The fractures compose two sets striking NW-SE and N-S. Gravels exposed in the uppermost part of the terrace are cut by few strike-slip, N-S striking, sub-vertical faults which can be traced along a vertical distance up to 50 cm. These faults cut the gravel matrix but omit clasts. Fractures cutting the clasts do show a well organized architecture which is independent of orientation of a-b surfaces of the host clasts. These features indicate that the fractures were formed in situ within the studied gravels. Furthermore, for the majority of fractures, the angle between the fracture and the a-b surface of the host clast is less than 80, confirming the in situ origin of fractures. The fractures of one set are parallel to the strike of the Sudetic Marginal Fault. This suggests that the origin of the fractures is related to that of the fault. The fractures of the second set may represent Riedel shears associated with the activity of the Sudetic Marginal Fault. The orientations of minor faults confirm this supposition. Summing up, we believe that during the Pleistocene, the Sudetic Marginal Fault was a dextral strike-slip fault, at least in the discussed area.

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Technologia współspalania paliw konwencjonalnych z biomasą i biogazem

Krawczyński M., Świerczewska A.

Biuletyn Urzędu Regulacji Energetyki

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2006

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nr 1

51-57

PL

Istotnym elementem realizacji zasady zrównoważonego rozwoju kraju jest zwiększenie udziału odnawialnych źródeł energii w bilansie paliwowo-energetycznym, co zarazem będzie sprzyjać osiągnięciu celów założonych w polityce ekologicznej państwa w zakresie zmniejszenia emisji zanieczyszczeń wpływających na zmiany klimatyczne. Ponadto zwiększy się bezpieczeństwo ekologiczne kraju poprzez decentralizację wytwarzania energii (generacja i kogeneracja rozproszona), zróżnicowanie źródeł energii, wykorzystanie lokalnych zasobów energetycznych, a także ograniczy szkody w środowisku związane z wydobyciem i spalaniem paliw konwencjonalnych (kopalnych). Stale wzrastające obciążenie środowiska powodowane jest przez zakłady przemysłowe, a szczególnie przez wytwórców energii elektrycznej, wykorzystujących paliwa konwencjonalne, których spalanie powoduje nie tylko emisję gazów cieplarnianych, ale również szkodliwych gazów i pyłów. Podpisany przez Polskę w 2002 r. tzw. Protokół z Kyoto (1989) nakłada obowiązek znacznego zredukowania tych niekorzystnych efektów dla zrównoważonego rozwoju energetycznego kraju. Ta problematyka jest również intensywnie rozwijana przez Unię Europejską, czego najlepszym przykładem może być Dyrektywa 2001/77/WE w sprawie wspierania produkcji na rynku wewnętrznym energii elektrycznej wytwarzanej w odnawialnych źródłach energii. Chcąc sprostać zaostrzającym się wymogom ochrony środowiska, przedsiębiorstwa energetyczne zaczęły poszukiwać „nowych” technologii wytwarzania, spełniających te wymogi. Stosunkowo prostym rozwiązaniem realizacji tych celów jest wdrożenie wspólnego spalania dotychczas stosowanych paliw kopalnych (węgiel kamienny, muły węglowe, itp.) i biomasy (drewna i jego odpadów) oraz biogazu.

12

Neofractures versus inherited fractures in structural analysis : A case study from Quaternary fluvial gravels (Outer Carpathians, Poland)

Tokarski A. K., Świerczewska A.

Annales Societatis Geologorum Poloniae

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2005

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Vol. 75, No. 1

95--104.

EN

This paper presents the results of a detailed analysis of flysch-derived clasts within Quaternary fluvial gravels exposed close to a map-scale overthrust. These clasts are commonly fractured. For a given population of clasts, the number of fractured clasts is positively correlated with the clast size and negatively correlated with the grain size of clast-forming rocks. The fractures comprise both those inherited from earlier joints cutting source strata, and those formed in situ within the gravels (neofractures). These two groups of fractures show different diagnostic features. The inherited fractures are orientated at random in relation to geographic coordinates, where as the neofractures show a well-organized architecture. The inherited fractures are mostly inclined 80–90° to the a-b planes of the host clasts, whereas the neofractures are usually inclined at 0–80° to these planes. The occurrence of neofractured clasts within the analysed gravels results from tectonic activity post-dating gravel deposition.

PL

W czwartorzędowych żwirach rzecznych odsłoniętych w pobliżu regionalnego nasunięcia w polskich Karpatach Zachodnich powszechnie występują spękane klasty skał fliszowych. W analizowanym materiale klasty skał drobnoziarnistych są częściej spękane, niż klasty skał gruboziarnistych. Obserwuje się też dodatnią korelację pomiędzy liczbą spękanych klastów a ich wielkością. Wśród spękań występują spękania odziedziczone po spękaniach ciosowych tnących skały macierzyste oraz neospękania, które powstały in situ w żwirach. Te dwie grupy spękań cechuje różna orientacja w stosunku do współrzędnych geograficznych oraz do powierzchni a-b klastów, tj. płaszczyzny zawierającej oś o maksymalnym (a) i pośrednim (b) wymiarze. Spękania odziedziczone są zorientowane chaotycznie w stosunku do współrzędnych geograficznych, podczas gdy orientacja neospękań jest uporządkowana. Spękania odziedziczone są zorientowane niemal pionowo (80-90°) względem powierzchni a-b klastów macierzystych, natomiast neospękania są zorientowane pod katami 0-80° do tych powierzchni. Pochodzenie neospękań jest wynikiem aktywności tektonicznej, która miała miejsce po osadzeniu analizowanych żwirów.

13

Tectonically-controlled sedimentation of Cenozoic deposits from selected basins along the Vietnamese segment of the Red River Fault Zone

Wysocka A., Świerczewska A.

Acta Geologica Polonica

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2005

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Vol. 55, no. 2

131-145

EN

Small, narrow sedimentary basins occur along the main faults in the Vietnamese segment of the Red River Fault Zone (RRFZ), which is the major discontinuity separating the South China and Indochina microplates. The sedimentary basins of the RRFZ are grouped into three main sections: along the Red River Valley, the Chay River Valley and the Lo River Valley. The sedimentary basins are filled with thick series of Palaeogene and Neogene clastic deposits that differ in type and origin. In the lower part of the basin fill, coarse-grained deposits predominate. In the upper part, different types of sandstones, siltstones and brown coal occur. There are no sediments of Late Pliocene age. Quaternary deposits are represented by sands and gravels. Biostratigraphical data are very poor, therefore only lithostratigraphical subdivision is applied. Thus, it is possible that deposits from adjacent basins associated with the RRFZ represent strata of different ages.The investigations were focused on the Lo River Basin (associated with the Chay River fault), Yen Bai Basin (associated with the Red River fault) and Co Tiet Basin (associated with the southwesternmost branch of the Red River fault). Thirteen sedimentary facies were recognised in deposits filling the investigated basins. The facies were grouped into five facies associations representing five distinct depositional environments. These comprise alluvial fan, gravel-dominated fluvial channel, sand-dominated fluvial channel, alluvial plain and lacustrine environments. In addition, the basin fills show features characteristic of strike-slip basins.

14

Evolution of small-scale deformation in relation to increasing calcite cementation in the sandstones of the Magura Nappe, Outer Carpathians (Poland)

Świerczewska A., Tokarski A. K.

Biuletyn Państwowego Instytutu Geologicznego

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2001

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nr 396

152-153

15

Joints and mineral veins during structural evolution: case study from the Outer Carpathians (Poland)

Świerczewska A., Tokarski A.K., Hurai V.

Geological Quarterly

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2000

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Vol. 44, Nr 3

333-339

EN

This paper focuses on mineral veins hosted in small-scale fractures within the Tertiary sandstones of the Magura nappe (Outer Carpathians). Joints, faults and tension gashes record three successive stages of the nappe structural evolution: (1) synsedimentary folding and thrusting, (2) regional rotation and (3) late-orogenic collapse. The flow of mineral-bearing fluids was channelized by small-scale fractures resulting in calcite and quartz-calcite veins. Folding: columnar calcite formed the most common filling of early joints and the joints-related tension gashes and strike-slip faults. The mineralisation was restricted to sandstones containing primary carbonates. Rotation: precipitation of columnar and fibrous calcite was largely restricted to joints reactivated as strike-slip faults. Collapse: the collapse-related mineralisation is the most abundant. Wide-spread fluid flow was channelized by normal faults resulting in fibrous calcite and quartz-calcite along these faults whereas several blocky and drusy calcite generation and single high temperature quartz-calcite assemblage precipitated in numerous adjoining joints.