Geo&Bio (Dec 2023)
Some Late Cretaceous agglutinated foraminifers from the Northern outskirts of Donbas, Ukraine
Abstract
The article describes four species of agglutinated foraminifers belonging to three genera (Verneuilina, Orbignyna, and Spiroplectammina) three superfamilies (Verneuilinoidea, Ataxophragmoidea, and Spiroplectamminoidea) and two orders (Ataxophragmiida and Ammodiscida, suborder Textulariina). Benthic species of foraminifers play an important role in the stratigraphic subdivision of the Upper Cretaceous deposits of the Northern outskirts of Donbas and correlation with adjacent territories, as they make up the most part of the assemblage in the samples. For this region, the foraminifera species Verneuilina muensteri Reuss, 1854, Orbignyna variabilis (d’Orbigny, 1840), Orbignyna pinguis Woloschyna, 1961, and Spiroplectammina baudouiniana (d’Orbigny, 1840) were monographically described for the first time. For each species of foraminifers, a detailed description of shell morphology is given. According to the biozonal scale of the Upper Cretaceous deposits of the East European Platform, Verneuilina muensteri is one of the characteristic species of the Upper Turonian Gavelinella moniliformis s. l. foraminifer zone, the species Orbignyna variabilis is typical for the Upper Santonian Gavelinella stelligera zone, and the species Orbignyna pinguis is characteristic of the Upper Campanian Globorotalites emdyensis zone. The species Spiroplectammina baudouiniana is also described. The stratigraphic and lateral distribution of each species of agglutinated foraminifers is indicated, and the deposits and sections of the Northern outskirts of Donbas in which they occurred are indicated. A schematic map of the region is presented, showing the studied sections in which shells of these species were found. These species are found in the rocks of the Shyroka, Yelanchyk, Kryva Luka, Sydorove, Konoplyanivka, and Kamianyi Brid formations of the Northern outskirts of Donbas, which are represented by chalk, marls, and calcareous sandstones. The work presents images of foraminifer species taken with a scanning electron microscope JSM-6490LV (JEOL Ltd., Japan). The article deepens our knowledge of some agglutinated foraminifers from the Upper Cretaceous deposits of the Northern outskirts of Donbas, which are characteristic species of the zone, contributing to further solving the issues of stratigraphy and correlation of these deposits.
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