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The first microfossil record of ichthyofauna from the Naujoji Akmenė Formation (Lopingian), Karpėnai Quarry, northern Lithuania

Dankina D., Chahud A., Radzevičius S., Spiridonov A.

Geological Quarterly

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2017

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Vol. 61, No. 3

602--610

EN

The assemblage of rare fish microremains of chondrichthyans and actinopterygians from Upper Permian deposits in Karpénai Quarry in northern Lithuania is described in detail for the first time. The deposits are characterized as reflecting a rapid phase of deposition of the Zechstein Limestone, interpreted as on a shallow shelf above storm-wave base in a proximal part of the Polish-Lithuanian Zechstein Basin. The actinopterygian microremains are represented by various teeth and a few scales from mostly palaeonisciforms and pycnodontiforms. The chondrichthyans are represented by various eusela- chian-type scales and a tooth of ?Helodus sp. The low abundance and low species diversity of the fossil assemblages studied may be due to arid palaeoenvironments that caused locally restricted conditions at this palaeogeographical location.

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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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Late Wenlock biostratigraphy and the Pristiograptus virbalensis group (Graptolithina) in Lithuania and the Holy Cross Mountains

Radzevičius S.

Geological Quarterly

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2006

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Vol. 50, No. 3

333-344

EN

Graptolites from Lithuania and the Holy Cross Mountains comprise a succession of the lundgreni, parvus (except for the Holy Cross Mts.), nassa, praedeubeli, deubeli and ludensis biozones of the upper Wenlock, the parvus, praedeubeli and deubeli biozones being recognized for the first time in Lithuania, where a graptolite-free interval may also be distinguished. P. virbalensis Paskevicius, 1974 and the virbalensis group are not widely known, and are discussed here. Analysis of P. virbalensis shows this to be an independent taxon, closely related to P. auctus. There are three species - P. virbalensis, P.jaegeri and P. auctus - in the virbalensis group.