Wyniki wyszukiwania - BazTech

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Upper Homerian (Silurian) high-resolution correlation using cyclostratigraphy: an example from western Lithuania

Radzevičius S., Tumakovaitė B., Spiridonov A.

Acta Geologica Polonica

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2017

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Vol. 67, no. 2

307--322

EN

The Gėluva regional stage stratigraphically corresponds to the late Wenlock. This time interval witnessed significant graptolite extinctions and turnovers of conodont faunas, as well as a large positive Mulde carbon isotopic excursion. Thus, the development of a detailed stratigraphy is a necessary step in understanding the complex patterns of regional and global variations in the sediments accumulating during the time interval studied. Therefore, in this contribution we present a cyclostratigraphic analysis of gamma ray (GR) logs from four wells, which are located in the deep water facies belt of the Lithuanian part of the Silurian Baltic Basin of the Gėluva regional stage. The analysis was performed using REDFIT spectral estimation, continuous wavelet transform and signal filtering techniques. As a result two 4th order and five 5th order cycles were distinguished and named in all sections. The correlation of cycles between sections was calibrated with the graptolite biozones. The comparative analysis revealed that intra-basinal cyclostratigraphic correlation could achieve resolution of the order of several tens of thousands of years.

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The colour analysis method applied to homogeneous rocks

Halász A., Halmai Á.

Geologos

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2015

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Vol. 21, No. 4

233--239

EN

Computer-aided colour analysis can facilitate cyclostratigraphic studies. Here we report on a case study involving the development of a digital colour analysis method for examination of the Boda Claystone Formation which is the most suitable in Hungary for the disposal of high-level radioactive waste. Rock type colours are reddish brown or brownish red, or any shade between brown and red. The method presented here could be used to differentiate similar colours and to identify gradual transitions between these; the latter are of great importance in a cyclostratigraphic analysis of the succession. Geophysical well-logging has demonstrated the existence of characteristic cyclic units, as detected by colour and natural gamma. Based on our research, colour, natural gamma and lithology correlate well. For core Ib-4, these features reveal the presence of orderly cycles with thicknesses of roughly 0.64 to 13 metres. Once the core has been scanned, this is a time- and cost-effective method.

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Integrated stratigraphy of the Oxfordian global stratotype section and point (GSSP) candidate in the Subalpine Basin (SE France)

Pellenard P., Fortwengler D., Marchand D., Thierry J., Bartolini A., Boulila S., Collin P., Enay R., Galbrun B., Gardin S., Huault V., Huret E., Martinez M., Smith C.

Volumina Jurassica

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2014

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Vol. 12, no. 1

1--44

EN

An integrated biostratigraphic approach, based on ammonites, calcareous nannofossils, dinoflagellates, combined with sedimentology, carbon-isotope and physical stratigraphy, is proposed for the Subalpine Basin (Thuoux and Saint-Pierre d’Argençon sections). Within the expanded marl deposits of the Terres Noires Fm., the Callovian-Oxfordian boundary is particularly well defined by ammonite taxa from different families (i.e. Cardioceratidae, Oppeliidae, Aspidoceratidae and Perisphinctidae), calcareous nannoplankton (first occurrence of large-sized Stephanolithion bigotii) and dinoflagellate cysts (first occurrence of Wanaea fimbriata). This precise biostratigraphy and diversity of ammonites permit long-range correlations with Boreal and Pacific domains. The exceptional outcrop conditions and continuous sedimentation allow high-resolution chemostratigraphy and cyclostratigraphy to be used. Variations of the δ13C record (1.5‰ increase during the Lamberti Zone), consistent with data from other sections of the Subalpine Basin and with the Paris Basin, provide additional markers to characterise the Callovian-Oxfordian boundary. Promising results from cyclostratigraphy should serve to constrain the duration of biostratigraphic units and thus improve the Late Jurassic Geologic Time Scale. Comparisons are made with the two other candidates for an Oxfordian GSSP, Redcliff Point (UK) and Dubki (Russian Platform). Finally, the advantages of the Subalpine Basin sections support the proposal of Thuoux as a suitable GSSP candidate for the base of the Oxfordian Stage

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Od litostratygrafii do cyklostratygrafii-nowatorskie kierunki w badaniach Profesora Ryszarda Dadleza (1931–2008)

Pieńkowski G.

Przegląd Geologiczny

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2009

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Vol. 57, nr 5

387-392

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Cyklostratygrafia utworów batonu na podstawie badań podatności magnetycznej -- wstępne wyniki

Ziółkowski P., Hinnov L. A.

Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2009

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T. 35, z. 3/1

115-115