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Paleocene and Eocene deposits on the eastern margin of the Gulf of Gdańsk (Yantarny P-1 borehole, Kaliningrad region, Russia)

Kasiński Jacek Robert, Kramarska Regina, Słodkowska Barbara, Sivkov Vadim, Piwocki Marcin

Geological Quarterly

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2020

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Vol. 64, No. 1

29--53

EN

Lithological and palynological studies of Paleogene siliciclastic deposits from the Yantarny P-1 borehole located on the western coast of the Sambian Peninsula (Kaliningrad region, Russia) show that the succession is characterized by numerous sedimentary discontinuities related to lithification horizons and erosional surfaces. Sedimentary gaps are emphasised by hardgrounds. Palynological data suggest the Selandian-Priabonian age of the succession and indicate a number of significant stratigraphic gaps. An important change in heavy mineral composition is recognized between the Paleocene and Eocene deposits in the area studied. A significant number of reworked Cretaceous microfossils is observed in the Selandian part of the succession studied.

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The interpretative significance of ripple-derived sedimentary structures within an upper Neogene fluvial succession of central Poland

Maciaszek Piotr, Chomiak Lilianna, Wachocki Robert, Widera Marek

Geologos

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2019

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Vol. 25, No. 1

1--13

EN

Sedimentary structures discussed in the present study are genetically linked to ripples that consist of pure sand or alternating sand and mud layers. All types of ripple-related structures, such as climbing-ripple cross-lamination and heterolithic bedding, i.e., flaser, wavy and lenticular (nodular), have been identified for the first time in fluvial strata that have been characterised previously as commonly massive. These small-scale bedforms, produced by migrating ripples, have been documented in a fluvial channel of late Neogene age in central Poland. The abundance and co-occurrence of the structures discussed and their spatial distribution provide evidence of their formation under very low-energy conditions, when flow velocity changed markedly, but was often significantly less than 0.5 m/s. Therefore, these ripple-derived sedimentary structures are here recognised as typical of channel fills of an anastomosing river.

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Mykolaiv Sands in Opole Minor and beyond : sedimentary features and biotic content of Middle Miocene (Badenian) sand shoals of Western Ukraine

Wysocka A., Radwański A., Górka M.

Geological Quarterly

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2012

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Vol. 56, No 3

475--492

EN

The Mykolaiv Sands are a huge lithosome of Middle Miocene (Badenian) age, accommodated within the Fore-Carpathian Basin in the Western Ukraine. Typically developed in the area of Opole Minor, it spreads across adjacent regions of Opole to cover an area of about 1300 km2. The varied sedimentary structures and ubiquitous burrows, indicate their development as a stack of sand shoals or related bodies, up to a few tens of metres thick, some of which temporarily reached sea level. Amidst the shoals, storm scours intermittently formed channel-like infills, some with residual lags at the base. The reversed density stratification and/or an increasing gravity gradient involved mass movements, some of which may have been triggered by seismic shocks focused at the shore or the adjacent hinterland of Podolia and Volhynia. Special attention is paid to the diverse fossils, all taphonomically filtered (aragonite shells and chitinous carapaces being lost), but which locally are mass-aggregated. They typify particular sand sets/bodies, to form allochthonous assemblages, some members of which (the cirripedes Scalpellum and Creusia, the shark Hemipristis, the ray Myliobatis) are newly recognized in the Ukrainian part of the Fore-Carpathian Basin. The others enrich considerably the faunal content of the Middle Miocene (Badenian) Paratethyan basins, either in terms of taxonomic diversity, or the eco-taphonomy of selected taxa (the starfish Astropecten, diverse echinoids). The whole faunal content of the Mykolaiv Sands may owe its profuse development to the global Middle Miocene Climatic Optimum of early Badenian age.