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Materia organiczna rozproszona w ciemnych turbidytach górnego eocenu płaszczowiny śląskiej (Karpaty zewnętrzne, Polska)

Waliczek Marta, Waśkowska Anna, Machowski Grzegorz

Przegląd Geologiczny

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2021

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Vol. 69, nr 7

458--462

EN

In this study, weapply microscopic analysis to evaluate thematurity of organic matter and characterise the macerals dispersed in the Upper Eocene shale samples from the Hieroglyphic Formation (Silesian Nappe, Outer Carpathians). The mean vitrinite reflectance values indicate the presence of organic matter immature to hydrocarbon generation (Ro≈0.43%).The main organic component dispersed in analysed samples is vitrinite, characteristic of kerogen type III.

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Łupki sylurskie platformy wschodnioeuropejskiej w Polsce : wybrane problemy poszukiwawcze

Porębski S.J., Prugar W., Zacharski J.

Przegląd Geologiczny

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2013

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Vol. 61, nr 8

468--477

EN

The pericratonic Silurian shale succession in Poland, despite its reasonably well-constrained geological framework, entails a number of contentious issues that need to be resolved before this emerging shale gas play will enter a stage of successful development. The succession is thought to have originated in a Caledonian foredeep encroaching distally onto a pericratonic shelf ramp. However, the geochemical signature of the mudrocks is consistent with a cratonic rather than orogenic sourcing, the proximal part of the foredeep basin-fill is apparently missing, and the shale succession juxtaposes in part across the Teisseyre-Tornquist Zone against suspected ter- ranes with no evidence of Silurian tectonism. Organic-rich Llandovery-Wenlock shales form a NW-SE striking central belt that is increasingly calcareous toward the craton (NE) and more silty toward the inferred orogen (SW), with the TOC content decreasing in both directions perpendicular to the strike. The TOC trend seems consistent with the deep-downlap model of black shale deposition suggested for many Paleozoic foredeep basins, but does not quite agree with the outer neritic to upper bathyal depths assumed for the shale deposition. Preliminary results from three wells drilled by Orlen Upstream in the Lublin Basin indicate that the Llandovery-Wenlock shales were deposited on a distal shelf ramp sheltered from the craton by shelf carbonate shoals and periodically affected by weak storm-generated currents. The impact of storms on water column resulted in intermittent rises of oxygen content in the otherwise anoxic to dysoxic near-bottom conditions. The prospective interval is dominated by calcite-cemented clayey mudstones showing moderate to good reservoir qualities. It is cut locally by ENE- or NE-dipping, steep fractures favourable for fluid transmissibility, and a NE or SW direction is most advantageous for artificial fracturing. This interval is capped with a Ludlow calcite-cemented, laminated siltstone that forms a regional correlation marker and shows soft-sediment deformations attributable to gravitational collapse on a NE-dippingpaleoslope. If correct, this interpretation might imply the encroachment of orogen-fed clinothem system onto the SW-inclined craton-margin shelf ramp.

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Graptolity : narzędzie stratygraficzne w rozpoznaniu stref perspektywicznych dla występowania niekonwencjonalnych złóż węglowodorów

Podhalańska T.

Przegląd Geologiczny

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2013

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Vol. 61, nr 8

460–-467

EN

In connection with the exploration of zones prospective for the occurrence of unconventional hydrocarbon deposits, numerous studies of source rocks have been conducted in Poland. Stratigraphic examinations are among the basic elements. The main group of fossils occurring in shale successions, being a potential source of hydrocarbons, is graptolites. This paper describes the assemblages of graptolites from Ordovician and Silurian deposits and shows their importance for the stratigraphy of shale complexes. Due to their abundance and rapid evolution, graptolites are an excellent tool for biostratigraphic dating, regional correlations and biozonation of rock successions in terms of the high-resolution sequence stratigraphy. The paper presents the significance of taphonomic research of graptolites to identify zones of increased accumulation of hydrocarbons in rocks. It has been found that graptolites are an equally important instrument, in addition to elevated TOC values or increased gamma ray radiation on well logs, that allows identification of potential source rocks for hydrocarbons, including shale gas.

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Wenlock (Silurian) graptolitic shales from the Kocaeli Peninsula (Derince-Izmit), NW Turkey

Sachanski V., Goncuoglu M., Gedik I.

Acta Geologica Polonica

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2008

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Vol. 58, no. 4

387-393

EN

Alternating dark grey to black thin-bedded limestones and yellowish-grey calcareous shales in a recently discovered section in Izmit (Derince), eastern Kocaeli Peninsula, yielded graptolites of the middle part of the Wenlock - Cyrtograptus lundgreni Zone and possibly Upper Cy. rigidus-Cy. perneri Zone. This is the first record of graptolitic shale facies rocks in the Kocaeli Peninsula. The succession described is more akin to the Silurian of the Zonguldak Terrane than the shallow-marine carbonate facies of the Istanbul Terrane. It is therefore suggested that the contact between the Istanbul and Zonguldak terranes should be located to the west of Izmit (Derince).