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卷 33, 编号 4 (2025)
- 年: 2025
- ##issue.datePublished##: 15.12.2025
- 文章: 7
- URL: https://journals.rcsi.science/2686-7397/issue/view/22086
Articles
Graptolite biozonation and stratigraphy of the Upper Silurian of the Kaliningrad region, Russia
摘要
The paper summarizes data on the Upper Silurian graptolite biostratigraphy and regional stratigraphy of the Kaliningrad region. Descriptions of local stratigraphic units, an updated graptolite biozonation and paleontological characteristics of graptolite biozones are provided. The biostratigraphical criteria for the recognition of the lower boundaries of the Ludlow and Pridoli series (the Gorstian and Ludfordian stages) in the Kaliningrad region are proposed. The Upper Silurian graptolite biozones of the Kaliningrad region are correlated with the standard graptolite biozonation and the graptolite biozonal scales of Lithuania, Poland and Barrandian.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;33(4):3-24
3-24
Paleobiogeography of the late Paleozoic family Annuliconchidae (Bivalvia: Pectinida) and its relation to paleoclimate and paleogeographic changes
摘要
The paleobiogeographic distribution of the fam. Annuliconchidae of bivalves in the late Paleozoic is analyzed. A list of all Annuliconchid localities with reconstructions of their paleolatitudes has been compiled. The stratigraphic interval of the family’s existence has been adjusted (Bashkirian Age of the Middle Carboniferous–Capitanian Age of the Middle Permian). It is shown that the family representatives had a low-latitude distribution in Laurasia and microcontinents located in the Paleotethys and Pantalassa. In the Northern Hemisphere, annuliconchids are not recorded north of the 32° paleolatitude, and in the Southern Hemisphere they are limited to 14° of the paleolatitudes. The change in the distribution range of the family demonstrates a connection with the climatic and paleogeographic events of the late Paleozoic. During the cold time, marked by an increase in the area of cover glaciations in the Southern Hemisphere, the range of distribution of annuliconchids shifted to the north, during the warming – to the south. The narrowing of the range in the Middle Permian was caused by the closure of the Ural Strait and the disappearance of the normal marine basin associated with Paleothesis on the territory of the East European Platform.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;33(4):25-39
25-39
New Data on Ammonites from Basal Beds of the Valanginian Stage (Lower Cretaceous) in the Lower Reach of the Anabar River, Northern Yakutia
摘要
A collection of ammonites from the basal beds of the Valanginian stage in the Klimovskii Utes key section, as well as in the Uryung-Khaya outcrop in the lower reaches of the Anabar River (northern Yakutia) has been studied. For the first time for a number of taxa (Bojarkia cf. mesezhnikowi, Neotollia cf. venusta and N. maimetschensis), descriptions and images are provided from these localities. It has been established that the basal beds of the Valanginian stage may include fauna of different ages. Both late Ryazanian Bojarkia ammonites and early Valanginian Costamenjaites and Subtemnoptychites are found here together. At the same time, it is not reliably determined whether the ammonite complex is mixed (condensation horizon) or whether stratification is preserved in the distribution of ammonites (condensed section). In the first case, the subface of these beds will also be the base of the Valanginian, and in the second case, the base of the Valanginian should be located inside these beds. The authors are inclined to the first interpretation, as suggested by previous researchers.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;33(4):40-51
40-51
Magnetostratigraphy of the danian stage of the volga right bank region near saratov. Article 2. belogrodnya formation–lower syzran subformation
摘要
The present paper provides a detailed description of the stratotype of the Belogrodnya Formation, which, like the Klyuchevskaya member, lies on the eroded surface of the Upper Cretaceous and is overlain by the Lower Syzran Subformation. The exact age relationships between the Klyuchevskaya member and the Belogrodnya Formation have not been established to date. The paper presents pioneering magnetostratigraphic data obtained from nine studied sections and new results of nannofossil stratigraphy. Two normal and reverse polarity magnetozones are identified and the approximate level of the geomagnetic inversion C28n–C27r is substantiated. According to magnetostratigraphic and micropaleontological results obtained, the Belogrodnya Formation cannot be younger than NP3 nannofossil zone. Based on the results of detailed correlation of sections using lithological, magnetostratigraphic, geochemical data, materials of mineralogical analysis of thin sections and information on the anisotropy of magnetic susceptibility, the structure of the Belogrodnya Formation has been clarified, the diachroneity of its boundaries has been established, a petromagnetic criterion has been proposed to substantiate the upper boundary.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;33(4):52-85
52-85
Palynostratigraphy and Deposition Environment of the Late Paleogene and Neogene Deposits of the Kulunda Plain of Western Siberia
摘要
The results of palynological study of the reference section of upper Paleogene and Neogene deposits of the Kulunda Plain, exposed by borehole 2 (settlement Ozeryanka, Novosibirsk Oblast) are presented. In the Tavda Formation, a dinoflagellate cysts assemblage of late Priabonian age and a palynoassemblage with Quercus gracilis–Q. graciliformis of the late Eocene were identified. Nine palynoassemblages have been identified from continental Oligocene and Neogene deposits: Carya spackmania–Carpinus perfectus–Tilia of the beginning of the second half of early Oligocene; Betula–Corylus–Pinus s/g Haploxylon of the second half of early Oligocene; Juglans sieboldianiformis–Pterocarya stenopteroides–Fagus of the end of the early Oligocene, possibly the beginning of the late Oligocene; Castanea–Quercus–Myrica of late Oligocene; Pinus s/g Haploxylon–Abietinieaepollenites sellowiiformis–Cupressaceae of early Miocene, presumably the end of late Oligocene; Alnus–Ulmus–Polypodiales of early–middle Miocene; Betula–Quercus–Ulmus of middle Miocene and Alnus–Polypodiales–Sigmopollis of middle–late Miocene; Betula–Artemisia–Amaranthaceae of late Miocene. Layers with freshwater dinocysts Pseudokomewuia sp. 1 were found at the top of the Zhuravka Formation. The deposition environment in the late Eocene, Oligocene and Miocene in the south of the West Siberian Plain has been reconstructed. The marine transgression in the Priabonian extended to the north of the modern Kulunda Plain. The first half of the Early Oligocene in the region experienced a hiatus. After a significant cooling at the Eocene–Oligocene boundary, climatic conditions again became warm and humid as evidenced by the distribution the growth of mesophytic coniferous-broadleaf forests with hickory. In the second half of the early Oligocene, the climate became colder and more humid, and the proportion of elements of the Arcto-Tertiary flora increased in plant communities. During the end of the early Oligocene and the late Oligocene, the climate became warmer, and broadleaf trees dominated the forests. At the end of the late Oligocene, the climate again became more humid, but remained warm, and pine forests predominated in phytocenoses, with the participation of ancestral forms of modern Cathaya. The cooling at the turn of the late Oligocene–early Miocene led to the predominance of conifers in forests; in the early Miocene, the proportion of small-leaved tree species increased sharply, and the participation of pine trees decreased. In the middle Miocene, the climate remained quite warm, but drier, and cypress trees disappeared from the plant communities. In the late Miocene, open plant communities are formed.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;33(4):86-112
86-112
Ostracods and Conditions of Formation of the Plevaka Section (Southern Azov Region) in the Late Kuyalnikian (Early Pleistocene)
摘要
The upper part of the Plevaka section (Taman Peninsula, Krasnodar Region, Russia) yielded an ostracod assemblage that for the first time indicates late Kujalnikian (Gelasian) age of the deposits. The association of Cyprideis pontica–Pontoniella acuminata–Scottia tumida is described as a new biostratigraphic unit (“beds with fauna”) for the Early Pleistocene of the Kerch-Taman Region. The upper clayey member of the section is shown to accumulate in an estuary with an unstable salinity ranging around 5‰ with a decreasing trend at the top of the section. The alternation of dominant species signals two intervals of arid and warm climate and an intermediate layer accumulated in more humid and cooler conditions. Two cycles of increasing bioproductivity are indicated by the change of a dominant form from S. tumida to C. torosa. Analysis of organic carbon (Corg) content showed three peaks of increasing bioproductivity when the number of ostracods, on the contrary, decreased, which is possibly associated with a decrease in the pH of the basin, leading to the dissolution of ostracod shells.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;33(4):113-127
113-127
Igor’ F. Nikitin and his “Golden Age” of Ordovician Studies in Kazakhstan
摘要
Biographical information is provided about Igor Fedorovich Nikitin (1924–2007), a renowned stratigrapher and paleontologist who played a significant role in the geological study of Ordovician sedimentary and volcanic-sedimentary complexes in Kazakhstan during the 1960s and 1980s. Nikitin worked for more than 60 years at the Institute of Geological Sciences in Almaty, Kazakhstan, where he authored or co-authored numerous monographs and contributed to the development of regional stratigraphic schemes for Kazakhstan. He proposed the structural zoning of Lower Paleozoic rocks in Kazakhstan, described numerous stratotypes and key sections, and determined the age of various formations and stratigraphic units. His work forms the basis for subsequent studies of Ordovician geology in Kazakhstan.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;33(4):128-136
128-136