Vol 27, No 4 (2019)
- Year: 2019
- Articles: 5
- URL: https://journals.eco-vector.com/0869-592X/issue/view/808
- DOI: https://doi.org/10.31857/S0869-592X274
ARTICLES
Late Ladinian to early Carnian radiolarians from the section of Pravyi Vodopadnyi creek, Omolon Massif, North-Eastern Russia
Abstract
The late Ladinian to early Carnian radiolarian assemblage is found for the first time in the Pravyi Vodopadnyi Creek Section, Omolon Massif, North-Eastern Russia. The assemblage consists of early Carnian radiolarian species that were previously described from sections of Kotel’nyi Island (New Siberian Islands): Glomeropyle aculeatum, G. cuneum and Pseudoeucyrtis annosus, and of species known from the late Ladinian of Dzugadzak Section (Omolon Massif): Glomeropyle algidum and Pseudostylosphaera omolonica. The taxonomic composition (dominance of genus Glomeropyle) indicates high-latitude, boreal nature of assemblage. The taxonomic affinity of coeval radiolarian assemblages of late Ladinian and early Carnian of Omolon Massif and New Siberian Islands gives opportunity for favorable estimation of radiolarian correlation of boreal Triassic.
3-12
Marine reptiles and climates of the Jurassic and Cretaceous of Siberia
Abstract
All available data on the Jurassic and Cretaceous climates of Siberia, based on isotope, palaeontological and lithological markers are summarized. Late Pliensbachian cooling, early Toarcian warming, followed by late Toarcian to Middle Jurassic cooling and long-term Late Jurassic warming are well-recognized. Gradual cooling started since the late Ryazanian and continued during the whole Early Cretaceous except the short early Aptian warming event. At the beginning of the Late Cretaceous climate became warmer with warming peak at the Cenomanian–Turonian transition. During the middle and late Turonian climate became colder. During the Coniacian–Campanian time interval climate became warmer, but at the end of the Campanian new cooling event occurred. New records of marine reptiles from the Toarcian, Kimmeridgian, Volgian and Santonian–Campanian of the north of Eastern Siberia are described. All data concerning marine reptile occurrences in the Jurassic and Cretaceous of Siberia are reviewed; these records (from 51 localities) are mostly located at high palaeolatitudes. The analysis has revealed that most of the localities containing fossil reptile remains were llocated in the Transpolar palaeolatitudes (70°–87°). There are no direct relationship between climate oscillations and distribution of these animals. Taking into account recent data arguing that nearly all groups of the Jurassic and Cretaceous big marine reptiles were able to maintain constant body temperature and also were capable make long-range seasonal migrations, any conclusions concerning usage of these animals as markers of warm climate should be treated with a caution.
13-39
The lower and middle Turonian (upper cretaceous) stratigraphy of the Yenisei Western Siberia (left side) region by foraminifers and inoceramids
Abstract
The article presents the results of the litho-biostratigraphic study of the lower part of the Upper Cretaceous sea deposits on the territory of the Bolshaja Kheta structural terrace on the left side of the Yenisei river in its lower reaches (the tops of the Dolgan suite, Dorozhkovo suite and the bottoms of the Nason suite; Turonian stage). Eleven lithological members surely extended on the Bolshaja Kheta structural terrace are selected. Each member has received the paleontological characteristic. The layers with fauna (inoceramids and foraminifers) are identified and compared with the zonal subdivisions of the Turonian in Western Siberia. It is established that the upper part of the Dolgan suite belongs to the Lower Turonian substages, the Mytiloides labiatus zone. Dorozhkovo suite in the studied area close to its stratotype area corresponds to the Lower and Middle Turonian.
40-58
Oligocene key section of South part of Eastern European Platform (North Ergeny)
Abstract
The section of well 768, depth 362 m, which opened the Eocene and Maikopian deposits is comprehensively studied and can serve as a reference one for both the Northern Ergeny and the entire northern part of Paratethys. The data on lithology, mollusks, and benthic foraminifera made it possible to break up the Oligocene part of the Maikop Group into formations and subformations: Tsimlyansk, Solenovian and Kalmyk parts, compare them with neighboring and distant parts of Parathethys, with a regostage scale, restore basic sedimentation conditions. Based on nannoplankton and dinocyst composition, these units were compared with the global zonal scale (Gradstein et al., 2012), and according to the spore-pollen data, the evolution of the climate of the Parathethys northern margin was restored. The phytoplankton, foraminiferal and paleomagnetic data show a strong reduction of the section in the Eocene part, where only negatively magnetized fragments of the Keresta, Kuma and Belaya Glina formations separated by unconformity surfaces were distinguished. In the lower Oligocene part we saw the full set of biotic and paleomagnetic zones. The lower part of the Solenovian formation (50 m) is rarely complete, unlike most of the Ciscaucasian sections. The Kalmyk formation in this section is probably incomplete and responds only to the first half of the Chattian.
59-92
Landscape and climat changes in Eastern Europe in the early Pleistocene
Abstract
The systematization of the original and published data on the geology and paleogeography of the Late Pliocene and Early Pleistocene of Eastern Europe was carried out due to the lowering of the Quaternary lower boundary to the level of 2.6 million years ago and the inclusion of the Gelasian stage in Quaternary system. It was revealed that at the bound of the Gauss-Matuyama paleomagnetic epochs, the profound landscape and climate changes took place. The rhythmic fluctuations of the climate intensified against the background of the general trend towards cooling and aridization. Subarctic landscapes appeared during the period from 2.6 to 1.8 Ma, which corresponds to the Gelasian stage (the Praetiglian and Tiglian stages of Western Europe or the Paleopleistocene of Eastern Europe). In the Eopleistocene (1.8–0.78 Ma) and Early Neopleistocene (0.78–0.42 Ma), the climate became colder while the structure of natural zonality repeatedly underwent a complex restructuring and gradually approached to the modern one. The presence of glacial deposits was noted in Eastern Europe already in the Paleopleistocene. The traces of at least three independent glaciations were revealed in the Eopleistocene, and four glaciations were suggested for the Early Neopleistocene. Based on the data from stratotype sections, paragenetic relations between heterochronous sediments in glacial and periglacial areas were established and Early Pleistocene paleogeographic events in Eastern and Western Europe were correlated.
93-116