Biostratigraphic Methods Research Articles

Geochemical and Biostratigraphical Evaluation of Lokpanta Shale in Abakaliki Anticlinorium, Anambra Basin Province, Southeast Nigeria

A geochemical and biostratigraphic method has been applied to explore the quality of organic matter, thermal evolution, potential hydrocarbon source and type of fossils of Lokpanta Shale from the Abakaliki Anticlinorium, Anambra Basin Province, Southeast Nigeria. Data obtained reveal that the total organic carbon (TOC) (2.18wt%) of the shale constitutes that of good to excellent source rock with gas-prone kerogen indicated by Rock-Eval S2/S3 (2.32). The low oxygen index (OI) (27.20 mgCO2g-1TOC) suggest deposition under low energy environments. The plots of HI against Tmax classified the organic matter as Type III kerogen. The poor concentration of OM is thought to account for its current hydrogen index (31.47 mgHCg-1TOC). The predominance of Type III kerogen in the Lokpanta shale suggests their potential to generate gas in the deeply buried sections. The Tmax values from the pyrolysis of the shales of the Lokpanta ranges from 428 to 442oC corresponding to maturity levels within the oil formation. The lamination of the sediments of the Lokpanta area with no burrows and the occurrence of dominantly planktonic foraminiferal assemblages also indicate a quiet water anoxic marine condition.

Pragian conodont biostratigraphy of the western slope of the Southern Urals (Mindigulovo section)

Research subject. Pragian conodonts from the Mindigulovo section on the western slope of the South Urals. Aim. Conodont-based biostratigraphy of the Pragian deposits. Materials and methods. This study is based on the biostratigraphic method: identification of conodonts using conventional techniques, recognition of Pragian conodont associations, zonal scale proposal and correlation. Results. The Pragian beds in the Mindigulovo Section in the latitudinal flow of the Belaya River are characterized using conodonts for the first time. The following conodont-based subdivisions at the rank of beds with fauna are recognized (from bottom to top): Beds with Gondwania irregularis, Latericriodus steinachensis, Beds with Pelekysgnathus serratus, Beds with Gondwania profunda, Pseudogondwania kindlei and Beds with Polygnathus cf. pireneae. Conclusions. The recognized conodont-based units can be directly correlated with the standard zonal scale of the Pragian. The conodont assemblage studied contains taxa characterizing the Gondwania irregularis–Gondwania profunda, Pseudogondwania kindlei–Eognathodus zeravshanicus, Polygnathus pireneae lineage, also known in the Pragian successions of Australia and the South Tien Shan. The co-occurrence of the deep-water family Eognathodidae and the shallow-water Icriodontidae in the Mindigulovo Section enables the correlation of different facies sections.

First palynological data from the Amat and Plyavinsky Horizons of the Main Devonian field

Research subject. Spores of higher plants from the Early Frasnian deposits of the Main Devonian Field. Material and methods. The work is based on the biostratigraphic method with the following stages: determination of the taxonomic composition of palynospectra, substantiation of the host rocks age, and data correlation. Palynological analysis was conducted using an improved technique by I.Kh. Shumilov and O.P. Telnova, which produced positive results. Results. For the first time, spores of higher plants were found in the sections of the Amatsky and Plavinsky Horizons of the Main Devonian Field. The palynospectra of the Podsnetogorsk layers of the Amat and Snetogorsk layers of the Plyavinsky Horizons were described. The palynospectra of the Podsnetogorsk layers are correlated with the palynoassemblage from the upper part of the Timan, and the Snetogorsk layers are correlated with the palynoassembly of the Sargaev Horizons, established in the Timan-Pechora province. The identified palynospectra complement the associations of vertebrate and invertebrate fauna, as well as rare macroflora, previously studied in these sections. The palynospectra from the Snetogorsk beds are correlated with the palynoassemblage of the Cristatisporites deliquescens – Archaeoperisaccus mennerii regional zone of the Timan-Pechora province. The palynozone characterizes the stratigraphic interval corresponding to the rugosa–transitans conodont zones (middle–upper part of the Sargaev Horizon). Conclusions. The established palynoassemblage from the Snetogorsk layers corresponds to the middle part of the Sargaev Horizon – the stratigraphic interval of the rugosa conodont zone. For the first time, the conducted palynological studies established a binding between the regional stratigraphic unit of the Main Devonian Field and the standard conodont zone.

Organic carbon isotope stratigraphy of Devonian-Carboniferous boundary sections in the Rhenish Mountains

The boundary between the Devonian and the Carboniferous has been drawn using ammonoids, conodonts and miospores, while geochemical data have only rarely been used. The sampling of eight sections (Aprath, Apricke, Effenberg, Wocklum, Stockum, Drewer WJ, Drewer WA, Marsberg) at the northern margin of the Rhenish Mountains demonstrates the potential of the isotope ratio of organic carbon to regionally correlate sections in different facies areas. With the help of the carbon isotopes, a distinct stratigraphic succession is documented, which is characterised by several positive and negative excursions; this succession was recorded in all examined sections. The carbon isotopes can therefore make a significant contribution to the stratigraphic subdivision of sections and complement the biostratigraphic methods.

Late Mississippian (early Serpukhovian) carbon isotope record of northern Laurussia: A proposal for the Viséan/ Serpukhovian boundary

The fauna provincialism in the interval led to the appearance of some problems with the tracing of this boundary with biostratigraphic methods. Therefore, it is important to determine auxiliary non-biostratigraphic markers of the boundary. The article is focused on the evaluation of the correlation potential of carbon isotope excursions near the Viséan/Serpukhovian boundary, with special attention to the northern Laurussia region. The biostratigraphically constrained carbon isotope record is revealed from the terminal Viséan ‑ lower Serpukhovian (Mississippian) shelf successions of the northern Laurussia (six key sections located in the north of Urals and Cis-Urals, NE Europe). Onset of a negative excursion in the middle part of the Lochriea ziegleri conodont Zone (lower Serpukhovian) shows amplitude of 1–2‰ and high spatial stability, and can be used as a stratigraphic marker in regional and global correlations.

Тефростратиграфия пограничных отложений юры и мела Западной Сибири

The age of tuffaceous interlayers, represented by tuffs and tuffites, which are common in the Upper Jurassic-Lower Cretaceous deposits of Western Siberia (the Bazhenovo, Tutleim and Frolov Formations), is discussed. The nature of these interlayers is associated with the subglobal (transfer of more than 1--2 thousand km) spread of volcanic ash (0.001--0.1 mm) and its sedimentation and burial in a vast epicontinental marine basin during episodes of low sedimentation rates, weak hydrodynamic activity and in the absence of bioturbation. Despite the extremely low thickness of these pyroclastic layers (<1 mm -- first cm), they are systematically noted in the drill core at certain stratigraphic levels. Tuffs and tuffites are clearly recognized due to sharp boundaries and contrasting color and mineral composition comparing to the host rocks. Moreover, these layers often demonstrate exceptionally bright luminescence in yellow and orange tones in the ultraviolet. Some of these pyroclastic layers can be traced over a vast area (more than 700,000 sq km) and hence can be used as isochronous stratigraphic markers. Considering the importance of the information about the distal pyroclastics in sedimentary strata, we have summarized data on boreholes in Western Siberia, containing tuffs and tuffites in the Upper Jurassic - Lower Cretaceous. Detailed linking of interlayers by drilling depth and geophysical logging was performed. The findings of more than 370 tuff and tuffite interlayers in the core of 136 wells have been catalogued. The age of tuffaceous interlayers is justified by the combination of lithostratigraphic and biostratigraphic methods, and geophysical logging. The key ammonite taxa recovered from tuff-bearing boreholes are figured. A brief description of the zones of the Ryazanian stage of Western Siberia and the principles of their identification are given. We suggest to replace the type index of the Surites analogus zone with S. subanalogus. The described sequence of tuffaceous interlayers is combined into 8 sub-regional pyroclastic levels traced throughout the central part of Western Siberia in the Middle Volgian (4 pyroclastic levels), Ryazanian (3 levels) and Lower Valanginian (1 level) intervals. The trace elements content composition of tuffaceous layers is characterized. The enrichment of rare earth elements in the direction from the oldest to the youngest interlayers ones was revealed, and the ratios Gd/Yb, Ho/Yb, Yb/Lu, Zr/Hf, Nd/Sm determine the stratigraphic correspondence of the tuffaceous interlayer to the subregional pyroclastic level. Our results can be used as a tephrostratigraphic scale for the Jurassic-Cretaceous boundary beds. Catalog of finds of Upper Jurassic -- Lower Cretaceous tuffs and tuffites in the core of wells in Western Siberia [<a href="https://doi.org/10.2205/2022ES000817-data">https://doi.org/10.2205/2022ES000817-data</a>] in text format is available on the website of the Earth Sciences Database Repository (BDNS) [<a href="http://esdb.wdcb.ru/">http://esdb.wdcb.ru/</a>], located at the Geophysical Center of the Russian Academy of Sciences.

New data on the stratigraphy and depositional environment of the Jurassic-Cretaceous boundary sediments of the northwestern part of the Yenisei-Khatanga trough

Research subject. Boundary Jurassic-Cretaceous sediments of the western part of the Yenisei-Khatanga Regional Trough. Materials and methods. The main correlation tools were seismostratigraphic, logging, and biostratigraphic methods. Litho- and biofacies methods were used to reconstruct the development conditions of the Yanovstan Formation and the NKh group of the Ryazanian Stage reservoirs. Results. The composition of macro- and microfauna complexes was defined, analogues of the ammonite and foraminiferal zones of the Upper Volgian substage and the Ryazanian stage of Siberia were established. The structure of the Upper Jurassic and Ryazanian complexes of the western part of the Yenisei-Khatanga Regional Trough was detailed. Conclusions were made about the formation conditions of the Volgian and Ryazanian deposits. Conclusions. The sediments were found to have been formed in a sea basin with stable salinity and low water energy, in relatively deep-water conditions. Mixed turbidite systems with multipoint supply sources were identified, in which the terrigenous material was supplied from southeast to northwest.

Конхилиофауна хазарских комплексов дагестанского побережья Каспия

The study of the biocomplexes of the Khazar horizons of the Dagestan coast of the Caspian Sea and the identification of faunal criteria for recreating the habitat conditions of paleobassins, which allows for more reliable reconstructions of individual stages of the Late Eopleistocene. Biostratigraphic and morphometric research methods were used to study the Khazar sediments and the mollusks contained in them. Various didacn complexes allow us to stratify the sediments containing them in detail. Changes in the composition of fauna in the section of marine sediments are mainly associated with environmental conditions and the nature of sedimentation, which allows us to indirectly use the change of different facies complexes as a periodization of sediments. The biostratigraphy of the Caspian Late Eopleistocene is based on evolutionary changes and patterns of ecological change in the communities of mollusks of the genus Didacna Eichwald in space and time. The study of the conchylofauna of the Khazar horizons of the Dagestan region of the Caspian Sea showed that two groups of crassa and trigonoides mollusks are mainly represented in the complexes, and the leading and characteristic species are identified. The analysis of the distribution of the main groups of didacnas by section, the stability of their composition and intergroup differences indicates a high reliability of the division of the Caspian sediments on this basis.

A new straton in the Late Devonian sedimentation in the Tsil’ma river basin of the Middle Timan

Research subject. Terrigenous rocks of the Sargaevo stage of sedimentation in various structural-facies settings within the Tsilma area (Middle Timan). Material and methods. The composition, structural features of rocks, and the species diversity of spores of higher plants were studied in the most complete natural outcrops proposed as a stratotype of the Paladinskaya Formation – a new straton of the Sargaevo age in the Middle Timan. Over a large area of the region, the deposits contain very few remains of fossil fauna, often indifferent. As a result, palynostratigraphy was selected as the main biostratigraphic method. Results. In the Middle Timan, a new straton, the Paladinskaya Formation, is described, which characterizes the Sargaevo stage of sedimentation in various structural-facies settings within the Tsil’ma area. The new straton has clear lithological and detailed palynological characteristics; a description of the limitotypes was performed.At present, the Paladinskaya Formation is the most complete sequence of Early Frasnian sedimentation in the European North-East of Russia, where it was possible to record regional responses to the global Frasnes event and to determine the position of the controversial level of the boundary between the Middle and Upper Devonian. Conclusions. The name “Ust’e Yarega” Formation in the Middle Timan cannot be considered valid, since it is a homonym of the sediments of the same age in the South Timan. The section is represented mainly by continental, rather than marine, deposits. A new name for the identifed formation is proposed – “Paladinskaya” with a description of the stratum section and limitotype.The Paladinskaya Formation is characterized by subcomplexes of spores (А and Б) of the regional miospore zone Cristatisporites pseudodeliquescens, which made it possible to correlate the marine and continental deposits of the Early Frasnian on the territory of the entire Timan-Pechora region and establish its exact position in the stratigraphic scheme of the Devonian.

ЛИТОЛОГО-ФАЦИАЛЬНОЕ СТРОЕНИЕ УФИМСКИХ ОТЛОЖЕНИЙ ЦЕНТРАЛЬНОЙ ЧАСТИ ПЕРМСКОГО КРАЯ

Актуальность исследования обусловлена необходимостью уточнения литолого-фациального и секвенс-стратиграфического строения отложений пермской системы. На сегодняшний день существует проблема стратиграфического положения и самостоятельности уфимского яруса. За последние три десятилетия исследователи высказывали разные предположения об изменении объемов яруса. Из-за особенностей осадконакопления основными биостратиграфическими группами для Волго-Камского региона являются: остракоды, пелециподы, споры и пыльца, растительные остатки, фрагменты рыб и позвоночных, интервалы распространения которых ограничены границами фациальных зон. Отсюда и возникает ограниченность биостратиграфических методов, из-за которых исследователям до сегодняшнего дня не удавалось четко определить границы и объём яруса. Цель: разделение отложений на секвенсы четвертого порядка и уточнения литолого-фациального строения. Объекты: геологические разрезы и глубокие скважины центральной части Пермского края. Методы: геокартирование геологических разрезов; скважинная корреляция; литолого-фациальное описание; палеогеографические реконструкции. Результаты. Проведение корреляции наиболее типичных разрезов помогло авторам описать строение, вещественный состав и построить сводный разрез уфимского яруса. Субмеридиональный профиль по изученным скважинам позволил показать смену типов разреза по площади от максимальных толщин в районе Соликамской и Висимской впадины, до нормальных в платформенной части Пермского края. В разрезе уфимского яруса выделено два секвенса четвертого порядка. Первый секвенс по объёму соответствует нижнесоликамской подсвите. Второй секвенс выделен в объёме верхнесоликамской подсвиты и шешминской свиты. Зафиксировано стратиграфическое несогласие с признаками субаэральной экспозиции на границе кунгурского и уфимского яруса и нижне- и верхнесоликамской подсвиты.

LARGE FORAMINIFERA FROM LIMESTONE IN THE RAJAMANDALA FORMATION, SUKABUMI, WEST JAVA

Rajamandala Formation is a limestone reef formation that is exposed in the Rajamandala – Sukabumi area, West Java. Different from those in the Rajamandala area, this formation which is located in the Sukabumi area is still rarely analyzed, especially from its large foraminifera. This study aims to assess the content, age, and depositional environment of reef limestone from the Rajamandala Formation based on large foraminifera. Research method was carried out in several stages. Sampling was done by spot sampling as many as 6 samples. Then, thin section observations was carried out using Olympus CX-22 binocular microscope. Finally, age and environmental analysis were carried out using basic biostratigraphic methods and cluster analysis based on the fossil content of large foraminifera. Result, the limestone reefs of Rajamandala Formation in Sukabumi area have varied material content. These rock ages were found to be in the Late Oligocene range (Chattian). This rock depositional environment is in shallow marine environment which is divided into 3 main clusters. The first cluster is dominated by Austrotrilina and Borelis which shows the Backreef shelf environment. The second cluster is dominated by Heterostegina and Cycloclypeus which shows the Forereef shelf environment. Finally, the third cluster is dominated by all large foraminifera representing the Reef environment. When compared with previous studies, the limestone of Rajamandala Formation in Sukabumi and Rajamandala areas has the same age and depositional environment.

Shift in the paradigm for GSSP boundary definition

For over 200 years the use of biotic events as the basis for the establishment of chronostratigraphic boundaries has been the only approach successfully utilized for international and national chronostratigraphy. The traditional biostratigraphic method provides relatively high resolution, averaging 1 Ma or sometimes less. This biochronological evolutionary approach to the Global Boundary Stratotype section and Point (GSSP) utilizes biotic Primary Markers (PM), with a few exceptions, encompasses the integrated PM and other non-PM markers as the general principles for defining GSSP boundaries and is a reasonably reliable mechanism for global correlation and a relatively stable International Geologic Time Scale (IGTS). The biotic PM's, however, possessed several serious restrictions: the nature of biological taxonomy, climatic, sedimentary, environmental - and directly applicable within the tropics-subtropics only. Biotic evolution and radiogenic isotopes are the only systems in geologic time that encompass the direction of time. The latter possessed less restrictions than the former. The recent tendency to define GSSP's utilizing magnetic chrons, climatic events and geochemistry may work in the Cenozoic, but is useless in the Mesozoic and older sediments because their cyclic nature (repeatedness) and the need for a second, directional in time index (biostratigraphic or radioisotopic) to place the PM in the right position within the scale. I propose here to utilize volcanic ash beds as the best Primary Marker in geologic chronostratigraphy. The U-Pb system is one of the most dependable of the geochronologic systems because it relies on a simple and non-interpretive radioisotopic decay constant. The ash-bed GSSP as a lithological horizon is universal for the GSSP definition and can be correlated as an age in any facies (marine, lagoon and continental), regardless of paleoclimatic zones, paleoceanographic, geochemical, and most other geological factors. Even moderate level metamorphism (>900 °С) does not affect the U-Pb dating of zircons. The GSSP at the base of a volcanic ash bed (Primary Marker) could be established in a short working time and these ash beds can be integrated with the existing as well as new biostratigraphic, geochemical, magnetostratigraphic and astronomical data (Secondary Markers) to create a robust, accurate and highly useable time scale. Several potential GSSP's that could be established with the volcanic ash beds close to the traditional and/or historical boundaries serve as examples for this approach and include Devonian-Carboniferous, Moscovian-Kasimovian, Kasimovian-Gzhelian, and Sakmarian-Artinskian boundaries.

Age of the coal accumulation in the Irkutsk basin based on accessory zircon dating in the Azeisk deposit tonstein (LA-ICP-MS)

The Irkutsk Coal Basin is located in the south of the Siberian Platform. The deposits of the basin are represented by Jurassic continental sediments. Since the 1970s, tuffs and tuffaceous rocks have been found in sediments of the Irkutsk Coal Basin, but so far only fragmentary information has been available on them. Previously, the age of sediments in the Irkutsk Basin was determined by the biostratigraphic method. We studied a section of the Cheremkhovo Fm., the most ancient formation of the basin, at the Azeisk coal deposit (in the area of the town of Tulun) with the aim of obtaining a geochronological constraints on the timing of sedimentation. The paper shows that tonsteins, which are transformed to clay ash-fall layers within coals, are suitable for radioisotope dating by accessory zircons. U-Pb dating of accessory zircons in tonstein from an industrial coal seam was performed using the LA-ICP-MS method. The obtained U-Pb age of 187.44 +0.45 –1.60 Ma, falling into the Pliensbachian Age, indicates the period of maximum coal formation in the Irkutsk Basin. This is the first radiometric age determination for the timing of accumulation of coal in the Irkutsk Basin. In the context of paleogeographic reconstructions, this age determines the upper limit of the tectonic quiescence period, which created conditions for lacustrine-boggy sedimentation in the vast territory of the Irkutsk Basin.

Main lady of russian paleontology. To the 165th anniversary of the honorary academician Maria V. Pavlova.

Maria V. Pavlova was the first Russian woman to achieve significant national and international success in her chosen specialty – vertebrate paleontology. She introduced the scientific world to a rich collection of Russian paleontological material, most of which she had collected and classified. In addition, she laid the foundation for programs to educate professional paleontologists, geologists, and biologists who would benefit from an understanding of biostratigraphic methods. Thanks to these and many other achievements, Pavlova is recognized as one of the founders of Russian evolutionary paleontology as an independent biological discipline.

Biostratigraphical investigations as a tool for palaeoenvironmental reconstruction of the Neopleistocene (Middle-Upper Pleistocene) at Kosika, Lower Volga, Russia

The Kosika locality is situated on the lowest terrace of the Enotayevka River (right channel of the Volga River) near Kosika village, in the Astrakhan region of the Russian Federation. This locality includes several sections, named Kosika 1–4 and Borehole 2 Kosika that are described in detail for the first time. Drilling, sediment descriptions, and sampling were performed during the 2008–2015 field seasons. Application of complex biostratigraphical methods and optically stimulated luminescence (OSL) dates were used to reconstruct the Neopleistocene (Middle-Late Pleistocene) palaeoenvironment in the Lower Volga area.During the Tyurkyan Period (at the early beginning of the Neopleistocene), regression of the Apsheronian Sea began. Lithological features and the presence of freshwater molluscs demonstrate that deposits accumulated in rivers and lakes under humid climatic conditions. Molluscs, ostracods, and dinoflagellates inhabited the Baku Sea. Climate was arid at the beginning of this period and humid during a later phase. Several changes affecting the marine and fluvial environments characterise the Early Khazar period. In particular, the climate oscillated from humid conditions at the beginning to an arid state, then returned to a more humid setting at the end of this period. These changes are indicated by palynological and malacological data. Regression of the Early Khazar Sea occurred during Singil time, when rivers, lakes, and limans (lagoons) existed. Large mammals inhabited plains that were covered by extensive vegetation. The climate during this period was humid and slightly cooler than the present day climate. Late Khazar and Khvalyn transgressions occurred during the Late Neopleistocene. When the Late Khazar Sea retreated from the territory, river valleys became the dominant landscape feature. Floodplains of Late Khazar rivers became sites of deposition of loamy and sandy material emplaced during flood events. At the end of this regressive period, the climate was arid and dry enough to allow for accumulation of anhydrite sediment in shallow lagoons and lakes. Afterwards, the Khvalyn transgression began, as indicated by the occurrence of specific key mollusc species. Fluvial-marine deposits formed geological bodies representative of an undersea delta, which in relief form the Baer Knolls. The modern Volga valley was formed during the Holocene.

Middle-Upper Quaternary stratigraphy in the northeast of European Russia inferred from rodent record and lithology of tills

We present the revision of materials on Quaternary rodent biostratigraphy (collared lemming Dicrostonyx and narrow-headed vole Lasiopodomys gregalis) in the northeast of European Russia testing the biostratigraphic method with lithological and palynological data. Petrographic composition of clastic material and orientation of clasts in tills are regionally stable lithostratigraphic criteria. Pechora (Dnieper) moraine is characteristic for clast axes oriented in the sector 340-60°; clasts in Vychegda (Moscow) till show orientation of 270–360°, which, in combination with the petrographic composition of erratic material, indicates the origin of moraines from different source glacial provinces. Certain differences were also found in the associations of heavy minerals. A specific trait of the Upper Neopleistocene Polar till is the presence of erratic crinoid-bryozoan limestones from Novaya Zemlya. Connection of this till with the Pay-Khoy-Novaya-Zemlya ice center and, possibly, with the shelves of the Barents and Kara Seas is also confirmed by the orientation of clasts from north-northeast to south-southwest.Middle Neopleistocene rodent remains are found between the Pechora and Vychegda moraines. By the ratio of M1 and M2 morphotypes all Middle Neopliestocene assemblages are divided into three groups representing morphs: D. simplicior morph 2 (Gavrilovka, Bolshaya Sluda, Akis’, Laya-4), D. simplicior morph 3 (Sercheyu-1, Laya-3) and D. ex gr. simplicior-gulielmi (Shapkina-4, Chuley, the lower horizon of Kipievo). These evolutionary levels respectively correspond to late Pechora (Dnieper, MIS 8), Rodionovo (Shklov, MIS 7) and early Vychegda (Moscow, MIS 6) intervals.Biochronological criteria for Late Quaternary based on evolutionary level of teeth of collared lemming and narrow-headed vole are suggested. It has been revealed that the early Valdai (MIS 5d-a–4) is characterized by the morph 2 D. gulielmi, as well as the high (about 50%) proportion of the gregaloid morphotype among the first lower molars of L. gregalis. Lemmings of morphs 2 and 3 D. gulielmi lived during the Middle Valdai (MIS 3), and animal of morphs 3 D. gulielmi and D. ex gr. gulielmi-torquatus existed during the Last Glacial Maximum. Lemmings at the levels of D. gulielmi morph 3, D. ex gr. gulielmi-torquatus, D. torquatus morphs 1 and 2 were typical for Lateglacial; morphs 1 and 2 D. torquatus – for the early Holocene; morph 3 D. torquatus – for the late Holocene and recent times. Small (less than 25%) proportion of the gegaloid morphotype is characteristic of m1 of Middle and Late Valdai and modern narrow-headed voles.

Litho- and Biostratigraphy of the Middle Neopleistocene of the European Northeast of Russia

The materials on litho- and biostratigraphy (collared lemming, Dicrostonyx) of the Middle Neopleistocene of the northeast Russia were revised and litho- and biostratigraphic methods were mutually tested for determination of the age of geological bodies. The reasonable stratigraphic division and correlation of the Neopleistocene are especially topical because of the current preparation of a new common stratigraphic chart of Quaternary sediments. The petrographic composition of the coarse-clastic material and the orientation of clasts in moraines are regionally consistent lithostratigraphic criteria. In the Pechora (Dnieper) moraine, the elongated rock clasts are oriented in a sector of 20°–60° in contrast to an azimuth of 270°–360° of the Vychegda (Moscow) moraine, which, in addition to petrographic composition of rocks, indicates the contribution of terrigenous material from different glacial provenances during formation of moraines. Certain differences were revealed also in assemblages of heavy minerals. The Middle Neopleistocene rodent fauna was found between the Pechora and Vychegda moraines. The stratigraphic position of microtheriofauna is identified on the basis of evolution level of molars of collared lemmings. By proportion of simplicior and henseli morphotypes for M1 and M2, all fossils belong to three groups corresponding to three evolution stages of a tooth system: Late Pechora (Late Dnieper, MIS 8), Rodionovo (Shklov, MIS 7), and Early Vychegda (Early Moscow, MIS 6). They include D. simplicior morph 2 (Gavrilovka, Bol’shaya Sluda, Akis’, Laya-4 localities), D. simplicior morph 3 (Sercheiyu-1, Laya-3 localities), and D. ex gr. simplicior—gulielmi (Shapkina-4, Chuley, lower horizon of Kipievo localities) morphs. These evolution stages correspond to Late Pechora (Late Dnieper, MIS 8), Rodionovo (Shklov, MIS 7), and Early Vychegda (Early Moscow, MIS 6) intervals. Taking into account the paleoclimate data, the presence of the lemmings in the region during the Rodionovo time is rather plausible.

AT THE BEGINNING OF THE BIOSTRATIGRAPHY (TO THE 250TH ANNIVERSARY OF THE BIRTHDAY OF WILLIAM SMITH)

The main side of the W. Smith’s work — geological mapping — has been shown to be expressed in the series of maps, created by him, and first of all in the «Map of layers of England and Wales». The layers represented for Smith an object for mapping. His stratigraphic tables constitute the lists of stratons, systemized in the order of their bedding and origin. W. Smith discovered a general sequence of 34 layers ofEnglandandWales, in more detailes separated the deposits, substracted later in the Jurassic system. Fossils were considered by W. Smith as specific features of layers, being mapped. The very combination of the characteristics of talented geologist — map-maker und collector of fossils — allowed making the famous conclusion that every layer contained the fossils, typical exactly for it. W. Smith showed the specifics and continuity of paleontological characteristics of different layers, predefined the oportunity of their recognition and identification and designed the base for the development of biostratigraphic method and historical geology in a whole. The short biographic data for Smith has been given.

Palaeoenvironment of the Middle and Upper Neopleistocene at the Gornovo Upper Palaeolithic site (Southern Ural foreland, Russia)

Complex biostratigraphical methods and radiocarbon dates were used to reconstruct the Middle (late Middle Pleistocene) and Late Neopleistocene (Late Pleistocene) palaeoenvironments covering the Palaeolithic period in the western foreland of the Urals. The Gornovo Palaeolithic settlement is located on the lowest terrace of the Belaya River. From the base to the top, this terrace consists of fluvial and lacustrine deposits of the Belaya horizon (Middle Neopleistocene; 427–364 ka), alluvial and lacustrine deposits of the Larevka horizon (Middle Neopleistocene; 364–334 ka), fluvial and lacustrine deposits of the Tabulda horizon (Late Neopleistocene; 57–24 ka), water-slope deposits of the Kudashevo horizon (Late Neopleistocene; 24–11 ka) and chernozem soil of the Holocene. The small and large mammals, insects, molluscs, and ostracods discovered in the deposits complete the palaeoecological characteristics of these periods. A diverse herbaceous steppe vegetation dominated during the Belaya Interglacial (a mixed coniferous forests with broad-leaved trees occurred in wet areas). The ostracoda species clearly indicate a cooling at the end of this time span. Molluscs inhabited the rivers and shores of freshwater ponds. The large mammals belong to the Middle Pleistocene fauna complex. During Larevka time span vegetation and fauna indicate cold climate conditions. The cold steppe communities typical of the beginning of this period changed gradually into communities that show an increasing role of the taiga. The ostracoda species confirm these cold conditions. Forest-steppe landscapes dominated during the second part of the Tabulda time span. Numerous ostracods as well as molluscs populated the lakes and floodplain basins. Entomological data show that the palaeoenvironment conditions were somewhat cooler than modern environment existing in the Southern Ural foreland. The large mammals of the Gornovo site belong to the Late Palaeolithic complex with the specific presence of Camelus sp. The Gornovo forest-steppe small mammalian fauna developed in cool continental climate conditions when coniferous forests grew in the river valleys and when forest-steppe landscapes dominated in the water interfluves. The artefacts are characteristic of the beginning of the Late Palaeolithic (32–24 ka). The Kudashevo time is correlated with the late Valdai (late Late Pleistocene; 24–11 ka). The herbage-Artemisia-Chenopodiaceae grassland-steppe association covered most of the territory and a Picea forest with Betula and a small quantity of broad-leaved trees grew in wet depressions. The climate at the end of this period became colder. Freshwater and terrestrial molluscs were represented by rare widespread species while the ostracoda species indicate cold conditions.

Rodent palaeofaunas from Biśnik Cave (Kraków-Częstochowa Upland, Poland): Palaeoecological, palaeoclimatic and biostratigraphic reconstruction

A unique record of faunal changes from the late Middle Pleistocene until the end of the late Pleistocene was provided by rodent assemblages from Biśnik Cave in Poland. The 17 rodent assemblages, of different qualitative and quantitative composition, included a total of 25 species of various ecological requirements and associated with five types of climate, represented by over 8500 individuals. For biostratigraphic analysis, the following indices were used: the ratio of enamel thickness on anterior and posterior edges of tooth loops in the genus Arvicola (SDQ), and morphological teeth changeability of Microtus oeconomus and Dicrostonyx. All three biostratigraphic methods are consistent, and made it possible to determine the stratigraphic position of the rodent assemblages. The layers from 19 to 14 were deposited in Middle Pleistocene, and the layers from 13 to 1 were deposited in the Late Pleistocene. The layers 14 and 13 constitute the border between the Middle and Late Pleistocene. Climatic and environmental conditions (temperature and humidity, duration of vegetation season) during the deposition were reconstructed, based on the assemblages representing the late Middle Pleistocene (layers 19–14; MIS 7-6), the Eemian interglacial (layers 14, 13; MIS 5e), and the Vistulian (Weichselian) glaciation (layers 12–1; MIS 5d-2). The analysis of bioclimatic indices made it possible to determine the most probable climate during the deposition of the respective assemblages. The environmental preferences allowed reconstruction of the prevailing biomes in the environments of Biśnik Cave. The results of quantitative bioclimatic analysis indicate that the deposition of same of the assemblages may be associated with cold temperature climate. The values of 11 climatic indices show the oscillations of two types of climate, temperate and boreal, with oceanic and continental influence. Reconstruction values of 11 climatic parameters shows an interesting pattern of relative stability in almost all the climatic parameters. Only drought length shows a remarkable change across Middle and Late Pleistocene sediment sequences from Biśnik Cave.