Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Geological Quarterly

2 2005

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Stratigraphy and facies development of the upper Tithonian-lower Berriasian Niżniów Formation along the Dnister River (Western Ukraine)

Gutowski J., Popadyuk I. V., Olszewska B.

Geological Quarterly

2005

Vol. 49, No. 1

45--52

The deposits of the Niżniów Formation, exposed around Niżniów, mainly on the banks of Dnister River, accumulated in the most proximal, marginal position of the latest Jurassic-earliest Cretaceous epicontinental basin on the SW margin of the East European Platform. The Niżniów Formation directly onlaps a Palaeozoic substrate and consists of transgressive cliff-derived conglomerates, and sandstones and marls which pass laterally into shallow marine carbonates: mainly biomicrites, oncomicrites, and pelmicrites with an abundant benthic fauna dominated by nerineid gastropods. The thickness of the formation in the area studied ranges from 0 to more than 20 metres and was controlled bymorphology of the pre-transgression substrate (mainly built of Devonian clastic rocks), synsedimentary fault tectonics and pre-mid-Albian erosion. The age of the Niżniów Formation can be determined, on the evidence of benthic foraminifers encountered in thin sections, as most probably late Tithonian-early Berriasian.

Late Jurassic-earliest Cretaceous evolution of the epicontinental sedimentary basin of southeastern Poland and Western Ukraine

Gutowski J., Popadyuk I. V., Olszewska B.

Geological Quarterly

2005

Vol. 49, No. 1

31–-44

The following Late Jurassic depositional systems have been recognized in the WUkrainian and SE Polish margin of the East European Platform: shelf slope/basin, open shelf, carbonate ramp, siliciclastic shelf, fluvial/playa, deltaic/swamp, restricted marine/evaporate lagoon. Three depositional megasequences have been identified. Their upper boundaries have been dated by means of targeted stratigraphic studies, compilation of existing data and reinterpretation of stratigraphic correlation concepts respectively as: lower Kimmeridgian divisum/hypselocyclum zones boundary, uppermost upper Kimmeridgian and lower Berriasian. Analysis of thickness and depositional system architecture within themegasequences in six regional cross-sections indicates that depocentre was located in the SW margin of the Mid-Polish Trough during Oxfordian and early Kimmeridgian times and propagated in Tithonian time to the Lviv region. This can be explained by changes in the palaeostress field. Approximately N–S oriented extension during Oxfordian and earliest Kimmeridgian times was replaced by approximately NE–SW oriented extension in Tithonian time. The thickness pattern of the megasequences as well as proximity trends of the system tracts within the sequences clearly coincide with the depocentre propagation.