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Wstępne rozpoznanie petrograficzne i geochemiczne materii organicznej rozproszonej w skałach karbonu Pomorza Zachodniego

Nowak Grzegorz J., Karcz Przemysław, Massalska Barbara

Przegląd Geologiczny

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2023

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Vol. 71, nr 4

224--226

EN

he paper presents results of organic petrography and Rock-Eval pyrolysis studies of Carboniferous rocks from Western Pomerania (N Poland). Samples for the studies were taken from core of the DŸwirzyno 3 borehole. The thermal maturity level of organic matter is determined by the values of: 1) vitrinite reflectance VRo= 0.82–0.93% and 2) Tmax= 431–460°C, which indicate oil window maturity. Organic petrography studies have shown a presence of different macerals dispersed in the rocks studied. Vitrinite and inertinite are particles of humic origin, while most liptinite macerals are of aquatic provenance. The Rock-Eval data clearly indicate that the organic matter forms levels made up either of kerogen type III or of kerogen type II.

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Source rock potential of the Miocene sedimentary rocks in the Carpathian Foredeep of the Czech Republic

Geršlová Eva, Medvecká Lujza, Jirman Petr, Nehyba Slavomír, Opletal Vladimir

Geological Quarterly

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2022

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Vol. 66, No. 1

art. no. 1

EN

We determine the organic matter content, its thermal maturity, genetic type, and source rock potential of the Miocene sedimentary rocks in the Czech Carpathian Foredeep. In the Czech Republic the Carpathian Foredeep represents a peripheral foreland basin formed due to the tectonic emplacement and loading of the Alpine-Carpathian Thrust Wedge onto the passive margin of the Bohemian Massif. Random vitrinite/huminite reflectance measurements and maceral analyses were performed on 25 samples from the Carpathian Foredeep succession. Additionally, results of 135 TOC content measurements, 141 Rock-Eval pyrolysis analyses and 27 vitrinite reflectance measurements were used to evaluate the regional distribution and depth trends for the entire Carpathian Foredeep. The thermal maturity of organic matter is between the immature part and peak of the oil window (Tmax = 413–448°C). Beneath the Western Carpathian Thrust Belt, the thermal maturity reaches higher values (Rr = 0.43–0.58%, Tmax = 429–448°C). The hydrocarbon generation potential is poor or fair, even if the total organic carbon values indicate good or even very good source rock potential. This is mainly due to the prevailing gas-prone Type III kerogen. The best source rocks were observed in the Miocene strata of the southern and central segments of the area discussed.

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Petrographic, palynological and geochemical recognition of dispersed organic matter in the black Anthracosia Shales (Sudetes, south-west Poland)

Nowak Grzegorz J., Górecka-Nowak Anna, Karcz Przemysław Paweł

Geological Quarterly

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2022

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Vol. 66, No. 4

art. no. 36

EN

We describe the organic petrography, palynology and Rock-Eval pyrolysis values of lacustrine black shales termed the Anthracosia Shales (Upper Carboniferous/Lower Permian) in the Intrasudetic Basin (Sudetes, SW Poland). Samples were taken from cores of two boreholes: Rybnica Leśna PIG 1 and Ścinawka Średnia PIG 1. Maceral composition, miospore assemblage composition, palynofacies and geochemical characteristics of dispersed organic matter in the Anthracosia Shales were used to determine conditions of the environment and to evaluate their petroleum potential. Data from both organic petrography and palynology analyses enabled recognition of three broadly distinct organic associations in these shales: bituminous, humic, and intermediate, while Rock-Eval pyrolysis revealed the presence of bituminous and humic kerogen types I and III. Type I corresponds to the bituminous association, with amorphous organic matter (AOM) dominant in the palynofacies, and type III corresponds to the humic association with phytoclasts prevailing in the palynofacies. The thermal maturity of the organic matter is determined by the values of: (1) vitrinite reflectance VRo = 0.53–0.73%, (2) palynomorph 3–4 colour index, and (3) Tmax = 443–447°C, which indicate oil window maturity. Some of the TOC results (1.6–2.9 wt.%) indicate that the Anthracosia Shales are good and very good petroleum source rocks, though the thickness of this interval is low (4–5 m). Shales with TOC values <0.5 wt.% prevail, and may be classifed as poor source rocks.

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Geochemical characteristics, thermal maturity and source rock potential of the Oligocene Šitbořice Member of the Menilite Formation in the Ždánice Unit (Czech Republic)

Jirman P., Geršlová E., Pupp M., Bubík M.

Geological Quarterly

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2018

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Vol. 62, No. 4

858--872

EN

Rocks deposited in the Oligocene Paratethys are recognized as one of the most important source rocks in the Flysch Carpathians. The Šitbořice Member (uppermost NP23 to lowermost NP25 zone) represents the upper part of the Menilite Formation in the Outer Flysch Carpathians of the Czech Republic. This paper presents results of bulk geochemical analysis, Rock-Eval pyrolysis and organic petrography. The geochemical evaluation, source rock potential, kerogen type and thermal maturity were studied using borehole cores. Based on the classification of Peters (1986), the evaluated Šitbořice Member is mostly classified as a “very good” source rock according to TOC and variable, mostly “poor” to “good” according to the petroleum potential. However, the average petroleum potential value assigned the member to “good” source rock which is in accordance with the TOC classification if the “live” TOC is used. A comparable distribution between kerogen type II and III has been indicated by HI. Unlike this, the organic petrography observations show the organic matter belongs to the kerogen type II which corresponds to the relationship of residual hydrocarbon potential versus TOC and HI calculated based on “live” organic carbon. Presumed immaturity was confirmed by Rr and Rock-Eval Tmax. Oxygen-restricted conditions ora dysoxic environment have been indicated by the TOC/TS ratio.