Vol 53, No 8 (2019)

Planktonic Foraminifera and Polycystina (Radiolaria) depict roughly similar—but not identical—worldwide distribution patterns. Discrepancies affect both cold- and warmwater areas, as well as the latitudinal profile of species richness, which peaks at the equator in Radiolaria, but in the subtropics in Foraminifera. Some differences are probably due to group-specific dissimilarities, but preservational and methodological artifacts play a key role.

Sediments of Maloe Olen’e Lake in the central part of the Kaliningrad oblast were subjected to analysis of the botanical composition of peat, pollen analysis, and radiocarbon dating. Four local pollen assemblage zones as reflecting the dominant plant communities of the surrounding territories during the Holocene were assigned. Analysis of plant macrofossils resulted in the identification of the stages of floating mat vegetation development in the Late Holocene. The atypical sequence of peat deposition, with transition mire peat located above raised bog peat, was identified. Sediment accumulation rate was calculated according to radiocarbon dating.

Surface sediment samples from the East Siberian and Chukchi seas have been analyzed for the quantitative distribution, taxonomic composition, and ecological structure of diatom and dinoflagellate cyst assemblages. According to the results, the diatom and dinocyst distribution in surface sediments indicates the distribution of different water masses in the region.

New data on finds of representative diatom assemblages in the marine Cenozoic section of West Kamchatka (Kvachina Bay) are presented. Planktonic species of stratigraphic importance were found in the assemblages. Analysis of stratigraphic occurrence of various taxa in the section resulted in the identification of a series of biostratigraphic units with the rank of local zones. Correlation of the assemblages with the North Pacific diatom zonation is outlined. The early Oligocene to early Miocene age of the host deposits is concluded.

Three-dimensional SEM images of the radiolarian species Williriedellum salymicum Kozlova, 1983 were obtained for the first time, from the Berriasian–Valanginian Parvicingula khabakovi – Williriedellum salymicum biohorizon of the Bazhenov Formation (based on material from the Gubkinskaya and Radonezh boreholes). Using computer tomography (CT) and scanning electron microscopy (SEM) methods, in addition to optical microscopy, we were able to confirm the validity of the species Williriedellum salymicum Kozlova, 1983 and we propose that this biohorizon be included in the Lower Cretaceous regional stratigraphic scheme of Western Siberia.

The agglutinated foraminiferal species Sculptobaculitesgoodlandensis has been studied to determine the composition of the cement and grains that make up the test wall. Elemental mapping of the internal structure reveals a layered wall with quartz grains in calcitic cement on the edges of the wall and an inner, calcitic layer of mixed detrital calcareous grains and fine-grained calcite, presumed to be secreted calcitic cement.

Kasimovian (Upper Pennsylvanian) conodonts are studied from the Shcherbatovka section (Oka-Tsna Swell, Ryazan Region). The Khamovnikian and Dorogomilovian substages are exposed in this section. The presence of the conodonts Idiognathodus turbatus and I. heckeli was established in the deeper-water facies, compared to the type area of the Khamovnikian Substage. These species are considered as the potential markers for the lower boundary of the global Kasimovian Stage of the Carboniferous. A similar assemblage is established in the sections of US Midcontinent and South China.

Analysis of the morphology of the Late Famennian–Early Bashkirian ostracod families Editiidae Knupfer, 1967 and Adeditiidae Gramm, 1992 allows the recognition of three groups with consistent sets of morphological traits. Accordingly, three new genera can be recognized in the family Editiidae Knupfer, 1967 and two new genera can be recognized in the family Adeditiidae Gramm, 1992.

Pathological phenomena in Devonian conodonts are separated into five genetic groups: (1) mechanical breakdown of hard tissues with and without subsequent regeneration; (2) deviation of the growth of hard tissues due to soft tissue breaking; (3) genetic changes; (4) diseases; and (5) results of normal functioning. Examples of the pathologies considered (Abrasio, Accessio, Caudatio, Depressio, Diminutio, Duplicatio, Fusio, Impressio, Jugatio, Occlusio, and Suppressio) are widely represented in the Devonian deposits of the Voronezh Anteclise.

Various methods for the study of microfossils (AR-PR₁) in macerates, thin sections, and fresh chips have been compared. Each method has its advantages and disadvantages. While working with thin sections, it is often impossible to trace the interrelation between microfossils and host rocks. When preparing macerates, only individual fragments of microorganisms can be observed, as a rule. The overwhelming advantage of the method for the study of rocks in fresh chips has been shown.

Bacterial paleontology studies the role of bacteria and other microorganisms in the genesis of sedimentary rocks and ores. Two model objects of bacterial paleontology (the Early Cambrian phosphorites and modern geyserites) are examples of the objects of research that have an extremely small number of morphological features (they are therefore almost not used in classification). For bacterial paleontology, it is important to find organic residues that were involved in sedimentation processes, in rocks and ores, and to determine to which groups of bacteria the forms found could be assigned. For this purpose, it is necessary to study rock, conditions of its genesis, and its mineral composition.