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Tectonics of the Wysoka Kamieńska Graben (NW Poland) and implications for fault sealing potential

Bobek Kinga, Konieczyńska Monika, Jarosiński Marek

Geological Quarterly

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2021

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Vol. 65, No. 3

art. no. 38

EN

Reservoir confinement by faults is important for safe storage of liquid waste or hydrocarbons. Having access to 3D seismic and borehole data, we have interpreted the tectonic setting of the Wysoka Kamieńska Graben (WKG) in the NW part of the Polish Basin and subsequently made an interpretation of the sealing potential of the graben-bounding faults. The formation and development of the graben in the Late Triassic and Early Jurassic was controlled by mechanical decoupling in the salts of the Zechstein Group. The primary tectonic factor triggering the graben origin was dextral strike-slip movement along the regional fault zone in the Paleozoic basement, transtensional accommodation of which in the Zechstein-Mesozoic cover led to development of a horse-tail pattern of grabens. During the Late Cretaceous, the graben underwent minor tectonic inversion. Sealing potential analysis of the graben-bounding faults was performed for the Triassic-Jurassic sequence including juxtaposition seal and fault gouge seal components. Finally, we have focussed our interpretation on the Jurassic sequence where the best reservoirs have been recognized. Our results indicate good to moderate sealing potential of the Hettangian reservoir, poor to moderate sealing of the Pliensbachian reservoir and lack of sealing of the Bajocian reservoir. Hence, the Hettangian reservoir, characterized by large thickness, low clay content and a large regional extent, acts as a potential storage formation, being confined by the graben-bounding faults of the WKG.

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Is the Złoczew lignite deposit geologically suitable for the first underground gasification installation in Poland?

Urbański Paweł, Widera Marek

Geologos

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2020

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Vol. 26, No. 2

113--125

EN

The present study focuses on alternative methods of exploiting lignite in comparison to conventional opencast mining and combustion in power plants for the generation of electricity. In Poland, opencast lignite pits cover large areas, creating social and environmental conflicts. In order to stabilise the production level of electricity and reduce the negative effects of opencast mining, alternative ways of exploiting lignite are suggested, one of these being underground gasification in situ. The Złoczew lignite deposit, which will most likely be exploited in the near future, provides an opportunity to discuss the unconventional method of underground coal gasification (UCG). On the basis of technological and geological criteria that have been established to determine the suitability of Polish lignite for underground gasification, resources to be used this way have been estimated. Through gasification, over 15 million tonnes of lignite can be utilised, which is about 2.5 per cent of resources of the Złoczew deposit intended for opencast mining. With this in mind, we suggest to take action by starting a pilot installation, to be followed by a commercial one for underground gasification after completion of superficial mining. Naturally, any future application of this method will be preceded by assessment of geological conditions at the Złoczew opencast pit.

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Seismically induced soft-sediment deformation in crevasse-splay microdelta deposits (Middle Miocene, central Poland) – reply

Chomiak Lilianna, Maciaszek Piotr, Wachocki Robert, Widera Marek, Zieliński Tomasz

Geological Quarterly

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2019

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Vol. 63, No. 2

429--433

EN

We expected that our paper on the crevasse-splay microdelta (Chomiak et al., 2019) would arouse the interest of other researchers for at least two reasons. First, this is the first such palaeoform discovered and described within the Mid-Miocene lignite seam in Poland. Second, the microdelta siliciclastic deposits are strongly deformed both ductile and brittle. Therefore, we would like to thank Tom van Loon for his effort to comment on our article, including his words of appreciation, and above all, for pointing out some of the terminological and interpretative shortcomings. Our reply will be in line with the issues discussed in his comment.

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Geochemical and mineralogical characteristics of calamines from the Olkusz zinc and lead ore district (South Poland)

Swęd Maciej Krzysztof, Duczmal-Czernikiewicz Agata

Geological Quarterly

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2019

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Vol. 63, No. 4

699--710

EN

The mineralogical and geochemical characteristics of calamines developed from chemical weathering within two different tectonic settings (tectonic horst and graben) are described. Calamines collected from the Olkusz-Pomorzany and the Bolesław zinc and lead mines were analysed geochemically by means of EMP and SEM-EDS and their mineralogical composition was identified by using reflected light microscopy and XRD analysis. The calamines from the Olkusz-Pomorzany mine are composed of marcasite, galena, cerussite, sphalerite, hemimorphite, smithsonite and goethite. Hemimorphite prevails over smithsonite and occurs in the vicinity of primary sulphides. The mineralogical composition of the calamines from the Bolesław area is less diverse. These are primarily composed of goethite and smithsonite, with a minor content of marcasite and remnant sphalerite. The mineral composition of weathering sites in the Olkusz-Pomorzany and Bolesław areas may reflect different geochemical conditions (from slightly acidic to alkaline pH values, from lower to higher CO2 partial pressure and solutions of different silica saturation) that could have changed over time. The mineralogical compositions of the calamines differ quantitatively and this could reflect the tectonic setting of the primary ore affecting the rate of chemical weathering.