JournalTOCs

Stratigraphy and Geological Correlation
Journal Prestige (SJR): 0.581

Citation Impact (citeScore): 1
Number of Followers: 2

Full-text available via subscription

Subscription journal
ISSN (Print) 0869-5938 - ISSN (Online) 1555-6263
Published by Springer-Verlag

[2469 journals]

Development of the Southern Coastal Area of the Caspian Sea during the
Pliocene–Quaternary According to Biostratigraphic and
Magnetostratigraphic Data
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The paper considers geological structure of the coastal region of the South Caspian, including paleontological and magnetostratigraphic dating of the Neogene–Quaternary deposits. Western and eastern segments of the region between the South Caspian Basin and the Alborz Ridge developed differently in the Late Cenozoic. In the west, marine sediments did not penetrate beyond the coastal plain into the neighboring lowered part of the Alborz Ridge during the Pliocene–Quaternary. This indicates the stability of the marine basin boundary or its expansion due to the abrasion of the Alborz slopes. In the east, a piedmont step emerged, bounded by thrust faults. The marine deposition at the piedmont step occurred in the Miocene. At the end of the Miocene, the marine sediments were folded and eroded. The Akchagylian (Piacenzian–Gelasian) marine sediments accumulated at the northern edge of the piedmont step. The Khazar fault raised these sediments up to 120–150 m and isolated the piedmont step. Thus, the expansion of the Alborz mountain building and the reduction of the South Caspian Basin occurred in the eastern part of the coastal area from the Late Miocene. The differences between the western and eastern segments of the coastal area are related to the development of the South Caspian Basin. Until the Late Miocene, it remained a residual trough of the Paratethys. During the Pliocene–Quaternary, the eastern part was filled with sediments up to 6 km thick and retained the features of a thinned continental crust 30–37 km thick with sedimentary cover up to 16 km thick. The western part of the basin was filled with sediments about 10 km thick and acquired the features of suboceanic crust with the Mohorovichich surface at a depth of 28–30 km with a thickness of the sedimentary cover exceeding 20 km.
  PubDate: 2022-08-01
Sr and Pb Isotopic Compositions in Dolostones of the Lower Riphean
Billyakh Group, Anabar Uplift: Step-Leaching Technique in
Chemostratigraphy and Geochronology
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: — This paper presents new age estimates and results obtained by the chemostratigraphic study of dolostones of the Billyakh Group, which consists of the Kotuikan and the Yusmastakh formations. The Billyakh Group forms the upper part of the Riphean section of the Anabar uplift in northern Siberia. The stepwise dissolution technique was used for the first time to determine the 87Sr/86Sr, 206Pb/204Pb, and 207Pb/204Pb isotopic ratios in dolostones. The Rb‒Sr systematics was studied by the chemical removal of about a third of the crushed sample (fraction L1) by the preliminary acid leaching in 0.2 N CH3COOH and the subsequent partial dissolution (fraction L2) of the remaining part of the sample in CH3COOH with the same concentration. The Pb‒Pb isotope systematics of dolostones was studied by the six-step dissolution of crushed samples in 0.5 N HBr. These procedures led to the removal of secondary carbonate material and greatly improved the quality of Sr chemostratigraphic and geochronological information. The initial 87Sr/86Sr ratios of the least altered carbonate material (fraction L2) of the Billyakh Group dolostones are 0.70502 ± 0.00029 in the Kotuikan Formation, 0.70519 ± 0.00026 in the lower subformation of the Yusmastakh Formation, and 0.70511 ± 0.00018 in the upper subformation of the Yusmastakh Formation. The Pb‒Pb age of early diagenesis of Kotuikan and Yusmastakh dolostones (1519 ± 18 Ma at MSWD = 1.8) was calculated from the results obtained for carbonate fractions L3–L6. Secondary carbonate fractions L1‒L2 are characterized by a Pb‒Pb age of 1466 ± 54 Ma at MSWD = 0.6. The δ13C values vary from ‒1 to ‒0.4‰ in dolostones of the Kotuikan Formation and from ‒0.4 to +0.8‰ in those of the Yusmastakh Formation (from ‒0.1 to +0.4‰ in the lower subformation and from ‒0.4 to +0.8‰ in the upper subformation). Comparison of these variations, as well as variations in the initial 87Sr/86Sr ratios in dolostones of the Kotuikan Formation and the Lower and Upper Yusmastakh subformations (0.70460‒0.70499, 0.70450‒0.70525, and 0.70462‒0.70523, respectively), does not make it possible to distinguish these units on the basis of chemostratigraphic characteristics.
  PubDate: 2022-08-01
Provenance of the Upper Triassic–Lower Jurassic Flysch and the
Middle–Upper Jurassic Coarse Clastic Sequences in the Cimmerides of the
Crimean Mountains Based on the Results of U–Th–Pb Isotopic Dating of
Detrital Zircon Grains
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: New results of U–Th–Pb isotopic dating of detrital zircon grains from the sandstones of the Upper Tauric Formation of the Crimean Mountains, belonging to the Lower Jurassic part of the Tauric Group, are presented. Comparison of the obtained age sets of detrital zircon grains with similar data for the clastic rocks of both lower and higher stratigraphic levels of the Cimmerides of the Crimean Mountains shows a significant difference between them. This reflects radical changes in the sources of sediment supply for the studied strata, which took place at the Triassic–Jurassic boundary and at the beginning of the Middle Jurassic. During the Late Triassic–Jurassic time, the sedimentary basins of the Crimean Mountains were formed directly on the southern (in present-day coordinates) continental margin of the East European segment of Eurasia. During the Late Triassic, the vast Scythian–Tauric megabasin was located here. Mostly shallow-water sediments accumulated in its northern part, in the Scythian sedimentary basin, and flysch deposition took place in its southern part, in the Tauric deep-water sedimentary basin. The clastic components of the flysch are dominated by the products of destruction of the crystalline basement complexes of the Sarmatian segment of the East European craton (EEC), the equivalents of the crystalline complexes exposed at present within the Ukrainian Shield and the Voronezh crystalline massif. The clastic material was supplied to the Tauric basin in transit via the Scythian basin. At the Late Triassic and Early Jurassic boundary, detrital material from the EEC ceased flowing into the Tauric sedimentary basin. But detrital material, the primary sources of which were the crystalline complexes of Gondwana and the peri-oceanic complexes of the Rheic and Paleo-Tethys oceans, started to flow into it. This means that the paleogeographic situation on the southern margin of the East European segment of Eurasia changed dramatically during the Early Jurassic. The Scythian–Tauric megabasin as it existed during the Late Triassic disappeared. The Dobrogea–Crimea Uplift emerged in its northern part (Scythian sedimentary basin). However, no significant changes in the depositional environment took place in its southern part (Tauric sedimentary basin). Deep-water flysch accumulation continued there during the Early Jurassic. This inherited sedimentary basin is hereinafter referred to as Late Tauric to emphasize the difference of its sedimentary fill from the fill of the Tauric basin. At the boundary of the Early and Middle Jurassic or at the very beginning of the Middle Jurassic, sediment accumulation ceased in the Late Tauric sedimentary basin, and the Upper Triassic and Lower Jurassic strata, successively accumulated in the Tauric and Late Tauric basins, underwent deformations. Later, the system of subbasins of the Crimean Mountains formed on the basement composed of these deformed complexes during the Middle and Late Jurassic. The clastic material that accumulated in the system of subbasins of the Crimean Mountains during the Middle and Late Jurassic was mostly of local (regional) origin, but a new source of detrital material, which supplied Permian–Triassic detrital zircon grains to these subbasins, appeared in addition.
  PubDate: 2022-08-01
On the Stratigraphic Setting and Composition of the Ayanka Flora from the
Upper Cretaceous of Okhotsk-Chukotka Volcanogenic Belt, Northeastern
Russia
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Three floristic assemblages from the Upper Cretaceous volcanogenic deposits of the Bolshaya Ayanka River basin (Okhotsk-Chukotka volcanogenic belt (OChVB), Northeastern Russia) are described for the first time. The flora includes about 60 species of fossil plants. Conifers and angiosperms dominate; ferns are less diverse; horsetails, liverworts, ginkgoaleans, and cycads occur as single specimens. The Ayanka flora is similar to the Santonian–Campanian floras of Northeastern Russia and Northern Alaska (with Barykov, Late Bystraya, Ust-Emuneret, and, to a lesser extent, with the Ola and Early Kogosukruk floras), which allows to conclude the most probable Santonian–Campanian age of the studied flora. Floristic assemblages of the Ayanka flora reflect both slope vegetation dominated by conifers and vegetation of lowlands—river or lake banks—dominated by angiosperms. These assemblages demonstrate the penetration of plant communities dominated by advanced angiosperms from the coastal lowlands of the Anadyr–Koryak subregion to the territory of the volcanic highlands, where ferns and conifers are often found in the Late Cretaceous, and the relict plants of the Early and beginning of the Late Cretaceous are still preserved.
  PubDate: 2022-08-01
The Archean Tonalite-Trondhjemite-Granodiorite Association of the Karelian
Province: Geology, Geochemistry, Formation Stages and Conditions
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: On the basis of the available geochronological data, the main stages of formation of Archean rocks belonging to the tonalite-trondhjemite-granodiorite (TTG) association, with ages of about 3240, 3150, 2900, 2850, 2800, and 2750 Ma, are identified and characterized within the Karelian Province of the Fennoscandian Shield. The distinctive features of geological positions and chemical compositions of TTG rocks of different stages are shown. For example, early TTG melts could have been melted not from basalts of the greenstone belts of the Karelian Province, but from lower crustal basites or from early amphibolites of the Vodlozero domain. Features of the geological position, chemical composition, and εNd(t) isotopic evolution do not support the assumption that most of the TTGs formed from tholeiites of the greenstone belts, thus excluding their genetic connection with subduction of the ancient oceanic crust. The most acceptable model seems to be the formation of TTGs in the Karelian Province as a result of plume-affected melting of lower crustal mafites. Archean TTGs differ markedly from Phanerozoic plagiogranitoids not only in the shape and size of the massifs but also in a number of geochemical features, in particular, lower HREE, Sc, Y, and Ti contents.
  PubDate: 2022-08-01
Sources of Fine-Grained Alumosiliciclastic Material for the
Vendian–Lower Cambrian Rocks of the Podilian Transnistria: A Synthesis
of Lithogeochemical Data
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The lithogeochemical features (contents of major oxides and trace elements) are considered for Vendian and Lower Cambrian clayey rocks of the Volyn, Mohyliv–Podilsky, Kanyliv, and Baltic groups of the Podilian Transnistria, which indicate the composition of eroded rocks on a paleodrainage basin. The lithogeochemical data are evident of the change of petrogenic (underwent one sedimentation cycle) fine-grained clastic material by lithogenic (multiply redeposited) fine-grained alumosiliciclastic material in the section. The material was mostly sourced from felsic igneous rocks at a subordinate role of mafic igneous rocks, which were dominant only locally in the drainage basins. The geochemical data indicate a highly variable ratio of felsic and mafic igneous rocks in paleodrainage basins at a certain predominance of the former. The geochemical features of the clayey rocks also suggest a gradual change in the types of rivers, which supplied fine-grained alumosiliciclastic material to the sedimentation area. At the initial stage (Volyn–Hrushka time), there were rivers which drained the volcanic areas in contrast to, e.g., the Zharnivka–Studenytsya time, when the Kanyliv Basin was filled with the material of (i) large rivers, (ii) rivers that run through the areas with sedimentary rocks, and (iii) rivers that drained igneous and metamorphic terranes (Ukrainian Shield').
  PubDate: 2022-06-01
  DOI: 10.1134/S0869593822030029
Early Eocene Diatoms and Silicoflagellates of the Cis-Donets Monocline
(Russian Plate): Biostratigraphical and Paleogeographical Approaches
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The diatom assemblage of the Veshenskaya Formation studied in the borehole P-321 of the Cis-Donets monocline (southern part of the Russian Plate) is assigned to the lower Ypresian Moisseevia uralensis Zone. According to the available data, this zone corresponds to the Deflandrea oebisfeldensis and Dracodinium (=Wetzeliella) astra dinocyst zones and, accordingly, to the nanoplankton NP10 Zone. The presence of the zonal silicoflagellate species Naviculopsis foliacea confirms the Early Eocene age of the Veshenskaya Formation. The taxonomic similarity of diatoms and silicoflagellates of the region under consideration with silicofossil assemblages of Northern Europe suggests a stable link between these paleobasins at the beginning of the Early Eocene.
  PubDate: 2022-06-01
  DOI: 10.1134/S0869593822030030
Climatic Fluctuations and Sedimentation Conditions of the
Turonian–Coniacian Sediments of the Northwest Caucasus
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The results of integrated study of the Turonian–Coniacian sediments from the Abinsky district (Northwest Caucasus), which are represented by a rhythmic terrigenous-carbonate sequence, are discussed. The use of microfacial, X-ray diffraction, isotope, and micropaleontological analyses allowed us to reveal important changes in abiotic and biotic evolution during this interval. The peculiarities of carbonate sedimentation, as well as changes in the composition of foraminiferal assemblages, helped to establish fluctuations in the relative sea level, whereas isotopic studies assisted in defining climatic fluctuations. During the periods of accumulation of carbonate and clayey material, the area was occupied by a relatively deep-water open-sea basin with normal salinity. In the background of high temperatures, cooling pulses are also recorded within the studied interval. The position of the Turonian–Coniacian boundary in the section is revised.
  PubDate: 2022-06-01
  DOI: 10.1134/S0869593822030066
Genus Buchia (Bivalvia) in the Lower Cretaceous of the North Caucasus,
Transcaucasia, and Kamchatka
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Lower Cretaceous Buchia (Bivalvia) from little known localities of Transcaucasia and Kamchatka are figured and described for the first time; a brief overview of all known finds of this genus in the Lower Cretaceous of the regions under consideration and the areas of the North Caucasus adjacent to Transcaucasia is given. The findings of Buchia inflata in Kamchatka made it possible to clarify (to the early Valanginian) the age of the host rocks, while Hauterivian B. keyserlingi in Azerbaijan are the youngest finds of the genus in the Tethyan succession. The assessment of the biostratigraphic and biogeographic significance of new Buchia finds is given.
  PubDate: 2022-04-01
  DOI: 10.1134/S0869593822030078
Upper Cretaceous Deposits of the Volsk Structural Zone of the East
European Platform: Turonian–Lower Campanian of the Kommunar Section:
Paper 2. Macrofauna Review, Conclusions
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The vertical ranges of inocerams, belemnites, ammonites, echinoids, sponges, and brachiopods from lithologically monotonous carbonate rocks have been studied in the Kommunar section. The results obtained in the study of macrofaunistic assemblages confirm and complement the benthic foraminifera research data of distinguished units of the middle–upper Turonian, Coniacian, lower and upper Santonian, and lower Campanian basal horizon. The stratigraphically full upper Coniacian–lower Santonian interval in the Kommunar section has been identified in the Volga region for the first time. The defined macro- and microfaunistic biostratigraphic units have been correlated and discussed. The Boreal–Tethyan magnetochronological correlation of the Santonian–Campanian makes it possible to conclude that the Santonian lower boundary in different regions differs by about a million years, which is comparable to the duration of the Santonian.
  PubDate: 2022-04-01
  DOI: 10.1134/S0869593822030042
Age and Geodynamic Setting of the Lower Jurassic Sandstones in the Onon
Fragment of the Aga Terrane, Mongol–Okhotsk Fold Belt
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: — This paper presents the results of geochemical studies of sandstones of the Aga–Borshchovochnyi complex in the Onon fragment of the Aga Terrane (Tutkhaltui Valley) within the Mongol–Okhotsk Fold Belt, as well as the results of U–Th–Pb (LA-ICP-MS) geochronological and Lu–Hf isotope geochemical studies of detrital zircons from these rocks. It was established that the youngest population of detrital zircons in the studied sandstones has an age of 196 ± 8 Ma. This indicates the Early Jurassic age of the sediments that were previously dated as Middle Paleozoic. The geochemical features of sandstones suggest that they were deposited in the active continental margin or island arc setting at the final stage of the closure of the Mongol–Okhotsk Paleocean.
  PubDate: 2022-04-01
  DOI: 10.1134/S0869593822030054
Representatives of the Miaohe Biota from the Ediacaran (Vendian)
Pre-Shuram Strata of the Patom Highland, Siberia
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The carbonaceous macrofossils which belong to multicellular algae and which were previously known from the younger (>570 Ma) Miaohe biota are found for the first time in the Lower Vendian (Middle Ediacaran, ~580 Ma) rocks of the Ura Formation of the Patom Basin in Siberia. The Ura macrofossils include phytoleims of unbranched ribbon-like thalli preserved on the surfaces of silty mudstones. Among the fossils, the species Liulingjitaenia alloplecta and Jiuqunaoella simplicis are identified. The features of their structure are considered. The in vivo forms of the organisms and their colonies are interpreted. It is shown that these organic macrofossils were a noticeable detritus-forming component of the Ura Basin. The Ura macrophytes coexisted with the Early Ediacaran microbiota and composed a common ecosystem of the paleobasin, which formed shortly before the Shuram event and was significantly transformed after it.
  PubDate: 2022-02-01
  DOI: 10.1134/S0869593822010051
Gastropoda from Lower Cretaceous Deposits of Nimbolook Area, Eastern Iran
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Early Cretaceous gastropods occur on the eastern margin of Lut Block in Eastern Iran. The gastropod assemblage reported herein is from the Nimbolook section located in the west of Qayen. The section mostly includes marls and limestones. It was dated as Aptian owing to the findings of foraminifers, nannofossils and ammonites. The exposure provides a relatively well-preserved gastropod fauna from marls and limestones. New species Oligoptyxis khorasanica sp. nov. from the family Nerineidae is the first find of the genus in the Cretaceous of Iran. Finally, the new genus Purpuripullina, gen. nov. was proposed. It was previously included in the family Ampullinidae.
  PubDate: 2022-02-01
  DOI: 10.1134/S0869593822010063
Supracrustal Rocks of Uneven-Aged Archean Greenstone Structures of the
Karelian Craton of the Fennoscandian Shield at the Border with the
Svecofennian Block: Composition, Age, and Origin
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: New data have been obtained on composition and age of the Archean supracrustal complexes of the Yalonvara–Pertinjarvi, Korpijarvi, and Pastajarvi structures in the marginal part of the Karelian Craton of the Fennoscandian Shield in the conjunction area with the Svecofennian Orogen. The structures were typically attributed to the single Yalonvara–Ilomantsi greenstone belt. On the basis of geochronological, petrographic, and geochemical data, only the Korpijarvi and Pastajarvi structures with an age of 2.73 Ga can be considered as a continuation of the Hattu greenstone belt in the Ilomantsi province (Finland). More ancient rocks of the Yalonvara–Pertinjarvi structure, estimated at 2.95–2.93 Ga, can be compared with the Mesoarchean basalt–andesite–dacite–rhyolite stratotectonic association of the Hautavaara greenstone structure. The younger Neoarchean rocks metamorphosed under the high-temperature amphibolite facies conditions are composed of gneisses and amphibolites. The ancient greenstone rocks metamorphosed under the greenschist and epidote–amphibolite facies conditions are of tuff nature. The rocks of both complexes are similar in terms of geochemistry to volcanic rocks of the suprasubduction settings, but they are different in proportions of the material of the mantle wedge and subduction plate.
  PubDate: 2022-02-01
  DOI: 10.1134/S086959382201004X
Provenances of the Upper Precambrian Clay Rocks in the Southern Urals:
Results of Geochemical and Sm–Nd Isotope Geochemical Investigations
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Changes in (La/Yb)N, Eu/Eu*, tNd(DM), and εNd(t) values in Upper Precambrian clay rocks on the western slope of the Southern Urals are considered. The (La/Yb)N, Eu/Eu*, and εNd(t) average values in Riphean and Vendian clay rocks are 5.7–15.1, 0.58–0.74, and –14.6 to –5.1, respectively. This reflects the change in the composition of the source areas and fits well into the general outline of subglobal events established by traditional geological methods in the conjunction area of the eastern regions of the East European Platform and the modern Southern Urals. The Early and Middle Riphean sedimentary sequences (1750–1250 Ma) were formed mainly owing to the erosion products of the mature continental crust of the East European Platform (tNd(DM) = 2.8–2.4 Ga). However, the pre-Upper Riphean hiatus led, probably, to a significant change in the composition of source areas about 1 Ga. The increase in magnitude of εNd(t) to –5.9 and decrease in tNd(DM) to 2.0 Ga in clay rocks of the Biryan Subformation of the Upper Riphean Zilmerdak Formation compared to underlying deposits suggest the appearance of the juvenile crust in the erosion area. This indicates the accumulation of fine-grained sediments at the beginning of the Late Riphean under the influence of active rifting processes, which is not recorded by traditional geological methods. The significant increase in (La/Yb)N (to 13.1 on average), decrease in εNd(t) to –14.6, and increase in tNd(DM) up to 2.5 Ga in clay rocks of the Vendian Bakeevo Formation compared to the Riphean rocks are interpreted as the result of the accumulation of the Bakeevo deposits due to the supply of the products of glacial exaration of the basement mature rocks during the Marino glacial period. The significant increase in εNd(t) to –6.8 and rejuvenation of tNd(DM) to 1.8 Ga in Vendian mudstones of the Basa and Zigan formations compared to the rocks of the lower part of the Asha Group reflect the appearance of a new mantle or volcanogenic material in the catchment areas during the Middle Vendian.
  PubDate: 2022-02-01
  DOI: 10.1134/S0869593822010038
Biostratigraphy of the Lower–Middle Callovian of the Saratov Area (Volga
Region) Inferred from Microfauna
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The results of micropaleontological analysis of the boundary interval of the lower–middle Callovian in the TETs-5 section (Saratov) are presented. The taxonomic composition and distribution of foraminifera and ostracods in the section are studied. The ranges of the biostratigraphic units inferred from microfauna and their correlation with the ammonite scale are refined. Two foraminiferal zones of the East European Platform are established: Haplophragmoides infracalloviensis–Guttulina tatarensis and Lenticulina cultratiformis–Lenticulina pseudocrassa. The volume of the Lenticulina cultratiformis–Lenticulina pseudocrassa Zone ranges from the upper part of the lower Callovian (the upper part of the Koenigi Zone and the Calloviense Zone) to the middle Callovian. Two biostratigraphic units by ostracods are established: (1) the Acantocythere milanovskyi–Procytheridea cinicinnusa Zone corresponding to the Subpatruus Zone of the lower Callovian, to the lower part of the Ch. saratovensis biohorizon, and (2) Beds with Praeschuleridea wartae–Pleurocythere kurskensis corresponding to the terminal part of the Subpatruus Zone (the upper part of the Ch. saratovensis biohorizon), the Koenigi and Calloviense zones of the lower Callovian, and the lower part of the Jason Zone of the middle Callovian. The images of typical taxa are provided.
  PubDate: 2021-12-01
  DOI: 10.1134/S0869593822020022
New Data on the Middle Devonian Biostratigraphy of the Salair,
Southwestern Siberia
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The biostratigraphic data on the ammonoid, brachiopod, conodont, and ostracod assemblages of the Mamontovo and Zarechnoe horizons of the Salair were revised and analyzed. The stratigraphic succession of the Middle Devonian deposits of the Salair is clarified, and the new Zarechnoe Horizon, including the Akarachkino, Safonovo, and Kerlegesh beds, is proposed. The upper Eifelian ammonoid assemblage of the Agoniatites Zone, established in the upper part of the Akarachkino Beds, is the biostratigraphic level for global correlations. The upper Eifelian and lower Givetian brachiopod assemblage (Indospirifer padaukpinensis (=I. pseudowilliamsi)) characterizes the Safonovo Beds. Two middle Givetian brachiopod zones were recognized in the Kerlegesh Beds: Rhynchospirifer hians (=Ilmenia subhians) and Subrensselandia' salairica (=“Chascothyris” salairica). The conodont assemblage of the Akarachkino Beds characterizes the upper Eifelian. The middle Givetian conodont assemblage, including Icriodus difficilis Ziegler et Klapper, Polygnathus linguiformis klapperi Clausen, Leuteritz et Ziegler, Po. parawebbi Chatterton beta morphotype, Po. ovatinodosus Ziegler et Klapper, and Po. pseudofoliatus Wittekind, was found in the upper part of the Safonovo Beds. No conodont assemblage was found in the Kerlegesh Beds.
  PubDate: 2021-12-01
  DOI: 10.1134/S0869593822020034
Upper Cretaceous Deposits in the Volsk Structural Zone of the East
European Platform: Turonian–Lower Campanian of the Kommunar Section:
Paper 1. Geological Setting, Benthic Foraminifers, and Magnetostratigraphy
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The results of microfaunistic (benthic foraminifers) and magnetostratigraphic (paleomagnetic and petromagnetic) studies obtained in the lower part of the Upper Cretaceous deposits of the Kommunar section are presented. On the basis of the study of benthic foraminifers, the section consists of middle and upper Turonian, Coniacian, lower and upper Santonian, and basal horizon of the lower Campanian. In addition, all Coniacian zones and subzones of the East European Platform have been established. These data confirm the importance of the Kommunar section as a stratotype of the Volsk Formation (Coniacian of the Middle and Lower Volga region). In the Kommunar section, the Turonian and Coniacian are characterized by a normal polarity, and the Santonian and lower Campanian are characterized by a reversed polarity.
  PubDate: 2021-12-01
  DOI: 10.1134/S0869593822020046
Traces of Catastrophic Volcanic Eruptions in the Moscovian Stage (Middle
Pennsylvanian, Carboniferous) in the Central East European Platform
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Traces of extremely powerful explosive volcanic eruptions are documented in the southern Moscow Syneclise; the eruptions occurred in the Moscovian Age about 309 million years ago in Variscan orogenic regions adjacent to the East European Platform. Interbeds of altered volcanic ash, 5–15 cm thick, can be traced over the distance of tens of kilometers in the sediments referring to the Podolskian and Myachkovian substages of the Moscovian Stage. These interbeds are composed of calcareous clays of montmorillonite composition and contain grains of zircon, apatite, ilmenite, biotite, K-feldspar, and quartz. Two types of K-feldspar (authigenic and volcanic) referring to the sanidine group are identified. U–Pb SIMS dating of pyroclastic zircons from the tuffaceous bed at the boundary between the Podolskian and Myachkovian showed an age of 308.9 ± 2.3 Ma, and 40Ar/39Ar dating of volcanic sanidine at a higher level showed the age of 305.5 ± 2.7 Ma, which agrees well with the available age estimates for the stage boundaries in the Pennsylvanian. Analysis of the Late Paleozoic volcanism in the nearby regions showed that the most likely area where catastrophic explosions took place, with subsequent transportation of volcanic ash to the southern Moscow Syneclise, is the zone of the North Caucasus.
  PubDate: 2021-12-01
  DOI: 10.1134/S086959382202006X
Lower Callovian of Kanev Dislocations, Cherkasy Oblast, Ukraine: Ammonites
and Stratigraphy
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The Jurassic rocks of the area of Kanev glacial dislocations (Central Ukraine) with the Bathonian coastal marine (lagoon) and the Lower Callovian normal marine sediments have been studied, the upper part of which was unknown to the predecessors. The zonal and infrazonal scale of the Lower Callovian of Kanev dislocations are elaborated by ammonites and include four zones, five subzones, and 14 biohorizons: Elatmae Zone (the upper part: P. elatmae and P. vasily biohorizons); Subpatruus Zone (the uppermost part: Ch. saratovensis (G. toricelli) Biohorizon); Koenigi Zone with the Gowerianum (G. metorchum and G. gowerianum biohorizons), Curtilobum (G. indigestum, G. curtilobum, and G. crucifer biohorizons), and Galilaeii (G. galilaeii, s.l. Biohorizon) subzones; Calloviense Zone with the Calloviense (S. khvalynicum and S. kiselevi biohorizons) and Enodatum (C. enodatum planicerclus, C. e. enodatum, and C. e. aeeta biohorizons) subzones. This scale is compared with those of European Russia and Western Europe. It is found that the base of the Proplanulites koenigi Zone, which was distinguished by Karitzky (1887) in the sections of the north Kanev dislocations, biostratigraphically corresponds to the base of the eponymous Zone, which was distinguished by Buckman (1913) in North Yorkshire and used in a standard scale of Europe. The ammonites of the families Cardioceratidae, Kosmoceratidae, Perisphinctidae, and Macrocephalitidae common in the Early Callovian in the East European marine basin are revised and their evolution and biogeography are analyzed. It is shown that, at the beginning of the Callovian, this vast young epicontinental basin was a “pot” of neoendemic evolution of various groups of ammonites, which migrated from Arctic, West European, and West Tethyan biochorems. The western (Dnieper–Donets) marine area of the basin, which also includes the area of Kanev dislocations, was a main way for migration of marine organisms between the West and East European paleobiogeographic provinces. New species are described: Paracadoceras vasily Gulyaev, sp. nov., Sigaloceras fundator Gulyaev, sp. nov., and S. kiselevi Gulyaev, sp. nov.
  PubDate: 2021-12-01
  DOI: 10.1134/S0869593821070029