Biostratigraphic division of the Maastrichtian deposits of the northern outskirts of Donbas by foraminifers

Abstract

Purpose. Development of a zonal biostratigraphic scheme by benthic foraminifers from Maastrichtian deposits of the Northern outskirts of Donbas, by using the studied sections of the region as an example. Methodology. Microfaunistic analysis was used in the processing of the material. Shells were removed from 150-200 g rocks by the standard methodology in Franke chambers and studied, using the MBS-9 microscope. Results. The biostratigraphic division of the Maastrichtian deposits of the Northern outskirts of the Donbas by benthic foraminifers, previously proposed by the author for the Upper Cretaceous deposits of this territory, is presented. An analysis of the four Early Maastrichtian and two Late Maastrichtian foraminiferal complexes made it possible to distinguish three zones of foraminifers. In the Lower Maastrichtian, the following zones were identified – Neoflabellina retuculata (lower), Brotzenella complanata (upper), in the Upper Maastrichtian – Hanzawaia ekblomi (with lower subzone Cuneus minutus). The Neoflabellina retuculata zone has been defined by the characteristic species Neoflabellina reticulata, Orbignyna sacheri, Heterostomella bullata, Cibicidoides bembix, Osangularia navarroana, Bolivina decurrens, B. incrassata incrassata, Pseudovigerina cristata. The Brotzenella complanata zone is characterized by the following species: Brotzenella complanata, Spiroplectammina suturalis, Gaudryina pyramidata, Cibicidoides bembix, Eponides peracutus, Bolivina incrassata crassa, Pseudovigerina cristata. Species Hanzawaia ekblomi, Anomalinoides pinguis, Praebulimina imbricata, Cuneus minutus are characteristic of the Hanzawaia ekblomi zone. Correspondence of the foraminiferous zones to macrophaunistic is given: Neoflabellina retuculata to the subzone Belemnella licharewi / B. lanceolata, Brotzenella complanata – subzones of Belemnella lanceolata and Belemnella sumensis of the Acanthoscaphites tridens zone of the outskirts of Donbas, the lower part of the Hanzawaia ekblomi zone – the Belemnitella junior / Spyridoceramus tegulatus zone of platform Ukraine. According to the current stratigraphic schemes of Ukraine, the correspondence of the Maastrichtian foraminiferal zones to the local stratigraphic subdivisions of the Northern outskirts of Donbas is indicated. The paleontological characteristics of the Konoplyanivska (two subsuites) and Kamyanobridska suites, which according to the age corresponds to the Lower Maastrichtian deposits, were supplemented with new data. A comparison of the studied foraminifers with species of the Boreal province of the International Stratigraphic Scale was carried out, general species are indicated. Scientific novelty. "The stratigraphic scheme of the Upper Cretaceous deposits of the Northern outskirts of Donbas" is supplemented with new data. Practical significance. The biostratigraphic division of the Maastrichtian deposits of the Northern outskirts of the Donbas by benthic foraminifers can be used for interregional correlation, as well as for detailed mapping of this region.