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The position and age of flysch deposits in the Crimean Mountains (Southern Ukraine)

Oszczypko N., Ślączka A., Bubniak I., Olszewska B., Garecka M.

Geological Quarterly

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2017

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Vol. 61, No. 4

697--722

EN

The Crimean Mountains (CM) are regarded as part of the Alpine-Himalaya orogenic belt related to the collision of the Eurasian and African plates. Our research in the CM has allowed confirming the existence of at least two flysch formations of different ages: the Taurida Flysch Formation (Upper Triassic/Lower–? Middle Jurassic) and the Sudak Formation (uppermost Jurassic/Lower Cretaceous) in the western and eastern sectors of the CM, respectively. After the Middle Jurassic volcanism, the freshwater claystones with coal-bearing intercalations, as well as local alluvial fan conglomerates were deposited. Then, following the Oxfordian/Kimmeridgian marine transgression, three separated Tithonian/Berriasian carbonate platforms developed: Baydarska, Chatyr-Dag and Demerji/Karabi. At the turn of the Late Jurassic, the deep-water Sudak Basin (eastern sector of the CM) began to develop in the eastern periphery of the Demerji/Karabi carbonate platform. This basin, dominated by turbiditic deposition, was probably connected with the Great Caucasus sedimentary system. Finally, distal flysch sedimentation in the Sudak Basin was followed by debris-flow deposits, with huge blocks of Upper Jurassic limestones. These blocks were derived from destruction of the Karabi carbonate platform. During the Berriasian/Valanginian, the eastern sector of the CM began to subside. As a result, both carbonate platforms (western CM) and the debris flow fans of the Sudak Basin (eastern CM) were overlain by marly shales and/or distal turbidites. This type of deposition lasted until the Aptian/Albian. In the post-Albian period, the Alushta-Salgir tectonic zone was transformed into a SE-dipping thrust fault with at least 10 km amplitude of overthrusting.

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The Stebnyk Formation (Miocene) in the Boryslav-Pokuttya and Sambir nappes of the Ukrainian Carpathians: a record of environmental change in the Carpathian Foredeep

Oszczypko N., Uchman A., Bubniak I.

Geological Quarterly

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2016

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Vol. 60, No. 2

473--492

EN

The late Early–Middle Miocene Stebnyk Formation is a ~600–2000 m thick unit of the Boryslav-Pokuttya and Sambir nappes, which contains a molasse succession of the Carpathian Foredeep incorporated within the marginal part of the Outer Eastern Carpathian accretionary wedge. In the valley of thePrutRiver, between Deliatyn and Lanchyn, the Stebnyk Formation covers the alluvial fan deposits of the Sloboda Conglomerate and the deltaic deposits of the Dobrotiv Formation in the south, and the lagoonal salty clays of the Vorotyscha Formation in the north. The Stebnyk Formation is built of mainly rose, greenish and grey calcareous mudstones intercalated with several variable sandstone beds, including thick-bedded packages. The occurrence of tetrapod footprints and raindrop imprints, as well as the overall red-be character prove prevailing continental conditions during deposition of the formation, which is interpreted as sediments of a delta plain with distributary channels filled by the thick sandstone beds and associated by intercalations of thinner beds referred to channel levees and crevasse splays. The upper part of the Stebnyk Formation contains marine microfossils of the NN4 Zone, and locally to the NN5 Zone, corresponding to the early Badenian transgression in the region. In the regional scale, the Stebnyk Formation shows a polarity of facies, with a high contribution of conglomerates and thick-bedded sandstones in the lower part in the north west and fining to the south east, with transportation from the west and north west. The sediments accumulated in an elongated subsiding zone between the rising Carpathian orogen and the forebulge elevation of the foreland, in a warm and semi-dry climatic conditions corresponding roughly to the Mid-Miocene Climatic Optimum. The accumulation was balanced by a subsidence caused by sinking of the platform slab and by sedimentary loading.

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The Dobrotiv Formation (Miocene) in the Boryslav-Pokuttya and Sambir nappes of the Ukrainian Carpathians : a record of sedimentary environmental change in the development of the Carpathian Foredeep Basin

Oszczypko N., Uchman A., Bubniak I.

Geological Quarterly

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2014

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Vol. 58, No. 3

393--408

EN

The late Early Miocene Dobrotiv Formation, a 700–800-m-thick unit, was deposited in a subsiding platform margin, which become involved in the marginal part of the Outer Eastern Carpathian accretionary wedge. The sedimentary succession from the Sloboda Conglomerate up to the Dobrotiv Formation records a transition from alluvial fan through fan-delta to deltaic deposits, followed by the fluvial plain-channel facies of the Stebnyk Formation. The deltaic deposits are mud-dominated, with poorly developed thickening-up packets of beds. Efficient sediment accumulation was balanced by subsidence caused by subsurface loading. Emerged parts of the deltaic sedimentary system include tetrapod footprints and raindrop imprints. The general absence of mudcracks in the Dobrotiv Formation suggests a humid climate. Deposits of the Sloboda, Dobrotiv and Stebnyk formations form fining- and thinning-upwards clastic wedge successions along the Ukrainian Carpathians.

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Foreland provenance of thick conglomerates in the early stage of the Carpathian Foredeep development : the case of the Sloboda Conglomerate (Lower Miocene), western Ukraine

Oszczypko N., Uchman A., Bubniak I.

Geological Quarterly

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2012

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Vol. 56, No. 4

789--802

EN

The upper part of the Lower Miocene Sloboda Conglomerate, a 250–1400 m thick unit, was deposited mainly on an alluvial fan and fan delta during the early stages of Carpathian Foredeep development. During of the Old Styrian overthrust movements of the Carpathian orogen, a forebulge was formed, which supplied clasts to the conglomerate. The clasts are dominated by Late Proterozoic–Early Cambrian phyllites, while Paleozoic carbonates are common, and Mesozoic and other rocks are rare. The source area formed mainly by a prolongation of the Małopolska Massif that was involved in the forebulge; this was located close to a palaeovalley cut into Mesozoic and Paleozoic rocks, buried under younger strata. Additional material was derived from the advancing front of the Carpathian Flysch nappes.

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Tectonic evolution of the Outer Ukrainian Carpathians: constraints from flexure and gravity modeling

Bubniak I., Kolodiy V., Zoetemeiyer R.

Biuletyn Państwowego Instytutu Geologicznego

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2001

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nr 396

26-27