The refined Quaternary stratigraphic scale of the Fore-Urals and main events in Southern Urals Region

The refined Quaternary stratigraphic scale of the Cisuralian and Bashkortostan regions, approved by the Commission on the Quaternary System of the Interdepartmental Stratigraphic Committee in 2007, includes the Eopleistocene (with three superhorizons and seven horizons), Neopleistocene (with three superhorizons and 13 horizons), and Holocene (one horizon and three subhorizons). The first defined Holocene Agidel Horizon with three subhorizons, the Middle Neopleistocene Klimovka, and the Upper Neopleistocene Kushnarenkovo Horizon are correlated with the Shuvalov, Gorka, and Mikulino horizons, respectively. New names and reference sections are proposed for all the Eopleistocene units. Local formations are proposed for the horizons, whose stratotypes are located in the northern Fore-Urals. The Quaternary stratigraphic scale is correlated with similar scales of the Urals, the East European Platform, and the Lower Volga region. The scale takes into account all the available data derived from the analysis of original (sediments, faunal and floral remains), published, and archival materials, which make it possible to trace in detail the main Quaternary events that occurred in the Fore-Urals.     

Quaternary stratigraphy and developmental history of the Central Russian Periglacial–Loessal Province

As a result of complex investigation in the Central Russian Loessal Province, detailed lithologic, geochemical, paleopedological, and paleontological characteristics of the young deposits of the stratotype section Mikhailovka are obtained. They provide the basis for facies genetic differentiation, stratification, and correlation of particular horizons chronologically coordinated by paleopedological and paleontological data with the geological scale of the Neopleistocene. The loess–soil sequences corresponding to climatolites of the Lower, Middle, and Upper Neopleistocene are established and characterized. In dynamical history of the Central Russian Periglacial Loessal Province, thirteen paleogeographical stages of natural–climatic changes (seven warm interglacial and interstadial epochs, six cold epochs alternating with them) are revealed. A rhythmic climatic substantiation for the stratigraphical division of recent sediments in the investigated region is provided.     

Biostratigraphy of the Late Middle Pleistocene (Middle Neopleistocene) of the Southern Urals region

A summary of published and unpublished materials on the stratigraphy of the Late Middle Pleistocene (Middle Neopleistocene according to the Russian stratigraphic scheme) of the Southern Urals region is given. Deposits of different origin in the regional stratigraphic units are characterized. The results of mammalian investigations provide the basis for the stratigraphical subdivision. Mollusca and palynology are used for the reconstruction of the palaeoenvironments. The stratigraphical positions of the main Middle Neopleistocene localities and precise definitions of the stratigraphical scheme of the Southern Urals region are discussed. The Southern Urals subdivisions are correlated with the Western European stratigraphical schemes (Holsteinian–Saalian interval).     

The Ordovician Mukteian Horizon of the Siberian Platform: paleontological substantiation,distribution, and correlation of sections

The new-generation regional stratigraphic chart of the Siberian Platform was accepted by the Interdepartmental Stratigraphic Committee of Russia in April 2013. Two main supplements to the chart of 1979 were made: (1) the new scale of stages, accepted by the International Commission on Stratigraphy in 2008, was presented for the Ordovician System along with the previous British standard and (2) the nomenclature of the regional stratigraphic units was supplemented by the Mukteian Horizon, which occupies an intermediate position between the Vikhorevian and Volginian Horizons. The first substantiation of the necessity of viewing this stratigraphic interval as an independent horizon was made in 1980, after it had become possible to use well cores for a more precise definition of the paleontologic characteristics and boundaries of the Vikhorevian Horizon, originally detected from several isolated sections in the Irkut amphitheater with an indistinct boundary with the overlying Volginian Horizon. Recent data, particularly those from drilling, permit a more complete paleontological substantiation of the Mukteian Horizon, consideration of its distribution in different structure-facies zones, and correlation of type sections.     

The Neopleistocene of North European Russia: Stratigraphy,paleogeography, and paleoclimate

The Pleistocene sediments of North European Russia have been studied using different methods to establish their composition and identify the enclosed organic remains. The results obtained elucidate natural climatic environments of the Pleistocene and corresponding sedimentation cycles and development stages. Glaciation centers are identified for different Pleistocene epochs based on lithological criteria. The established secular trends characterizing spatial distribution and composition of different-age glacial horizons facilitate their regional correlation. Climatic conditions and paleogeographic settings of sedimentation during interglacial epochs of the middle-late Pleistocene and Holocene are reconstructed. Variations in development of vegetation, temperature, and humidity are detected for the first time in the Timan-Pechora-Vychegda, Arkhangel’sk and Vologda regions with parallel coordination of obtained data. As is concluded, there was a tendency of climate cooling in North European Russia during the Neopleistocene.     

Upper Neopleistocene ostracods from the southeastern West Siberian Plain and their stratigraphic significance

In the upper Neopleistocene of the southeastern West Siberian Plain, two ancillary biostratigraphic units by ostracods in the rank of faunal beds, namely, the Cypridopsis vidua–Herpetocypris reptans Beds (Ermakovo Horizon and the lower part of the Karginsky Horizon) and the Ilyocypris pustulata Beds (Karginsky Horizon), are recognized for the first time. The age of the Ilyocypris pustulata Beds is substantiated by a series of radiometric datings. The Eucypris pigra–Cyclocypris laevis–C. triangula ostracod assemblage from the upper part of the Sartan Horizon, whose age is also justified by a radiometric date, is characterized. The new data on ostracods supplement the materials available on this group of fauna and refine the Quaternary regional stratigraphic scheme of the West Siberian Plain.     

Middle Pleistocene environments,landscapes and tephrostratigraphy of the Armenian Highlands: evidence from Bird Farm 1, Hrazdan Valley

The significance of the southern Caucasus in understanding Pleistocene hominin expansions is well established. However, the palaeoenvironments in which Palaeolithic occupation of the region took place are presently poorly defined. The Hrazdan river valley, Armenian Highlands, contains a rich Palaeolithic record alongside Middle Pleistocene volcanic, fluvial and lacustrine strata, and thus offer exciting potential for palaeoenvironmental reconstruction. We present the first results of sedimentological, geochemical, tephrostratigraphical and biological (diatoms) study of the sequence of Bird Farm 1, located in the central part of the valley. These data show six phases of landscape development during the interval 440–200 ka. The sequence represents the first quantitative Pleistocene diatom record from the Armenian Highlands and the southern Caucasus, and indicates the persistence of a deep, stratified lacustrine system, with evidence for changing lake productivity that is tentatively linked to climate. Furthermore, major element chemical characterization of visible and crypto-tephra horizons in the sequence enables the first stages of the development of a regional tephrostratigraphy. Together, the evidence from Bird Farm 1 demonstrates the importance of lacustrine archives in the region for palaeoenvironmental reconstruction and highlights the potential for linkages between archives on both a local and regional scale.     

New data on mammoth fauna mammals in the central Lena River basin (Yakutia,Lenskie Stolby National Nature Park and adjacent areas)

This paper considers the data on new findings of mammoth fauna remains in the Middle Lena basin used to specify the species composition of large Late Neopleistocene mammals represented by eleven species. The obtained range of radiocarbon dates made it possible to state that mass burials of Pleistocene mammal remains were formed in the region during the Karginsk Interstadial (24 000–55 000 years ago).     

Quaternary mammal remains from the Krasniy Yar locality (Tomsk region,Russia)

The geological structure and faunal content of one of the principal localities for Quaternary mammal remains in Western Siberia, Krasniy Yar (Tomsk region, Russia) are considered. This locality contains 3 layers of bone remains: lower (Middle Neopleistocene), middle (the end of Late Neopleistocene) and upper (end of Neopleistocene—beginning of Holocene). The richest horizon in number of species and the quantity of remains is the middle horizon, which contains the mammoth fauna.     

Red palaeosols sequence in a semiarid Mediterranean environment region

In this work we study one of the most palaeopedological sequence formed in Central Spain, which is located on the Pliocene–Pleistocene erosional surface in the Madrid Basin. We also analyse its relationship to erosive and sedimentary Pleistocene events in order to obtain new data for a correct interpretation of the origin and evolution of forms at the top of tabular lands in this site. The geomorphic features and the properties of a sequence of very red palaeosols that developed on this old surface can help us in the understanding of the palaeoclimatic evolution of Central Spain in a Mediterranean climate. They were examined to identify pedologic and climatic changes during the Quaternary. The soil sequence comprises intercalated palaeoargillic and palaeopetrocalcic horizons. The clay minerals are mainly illite, kaolinite, smectite and sepiolite. The alternation of argillic and calcic horizons, limestone debris (cryoclastic colluvions) and aeolian sands suggests succeeding periods of phytostability and phytoinstability (biostasis/rhexistasis). Argillation, rubification and calcium carbonate accumulation were repeated throughout the Pleistocene and it is hypothesised that climatic conditions during numerous stages of this period were not very different from the present conditions.     

The Kantemirovka Paleogene reference section of the Voronezh region

The section on the outskirts of the town of Kantemirovka is proposed to serve as a reference one for Paleogene deposits of the Voronezh region. Observing the requirements of the current Stratigraphic Code of Russia, it is suggested to introduce the Middle Eocene Sergeevka and Tishki formations, which were defined previously by V.P. Semenov as mappable lithostratigraphic units instead of the Kiev Formation (regional stage) in the Paleogene stratigraphic scale of Ukraine, into the regional Paleogene stratigraphic scale of the Voronezh anteclise. The structure of the Sergeevka Formation and hypostratotype of the Tishki Formation defined in this section are considered with the analysis of the distribution of nannofossils, foraminifers, and diatoms in corresponding deposits. Benthic and planktonic foraminifers are used for defining regional biostratigraphic units, which are correlated between each other, with zones of the standard stratigraphic nannofossil scale, and units of the Middle Eocene Kiev regional stage of northern Ukraine. The boundary between the formations under consideration is universally marked by the replacement of carbonate sediments by terrigenous?siliceous facies, disappearance of calcareous fossils, and development of a new biota. These features allow the boundary between these formations to be conditionally correlated with that between the Keresta and Kuma regional stages of the North Caucasus region.     

Biostratigraphy of the Upper Pleistocene (Upper Neopleistocene)–Holocene deposits of the Lemeza River valley of the Southern Urals region (Russia)

Numerous caves and terraces with late Late Pleistocene (Upper Neopleistocene according to the Russian stratigraphic scale)–Holocene deposits are located in the Lemeza River valley in the surroundings of the Atysh waterfall, the native reserve territory of the Bashkortostan Republic. Lemeza River runs in the southern part of the western slope of the Urals and belongs to the Belaya River valley system (Russian Federation). A summary of the biostratigraphical investigations between 1992 and 2007 in this area is given. Deposits of cave and fluvial origin are characterized in the framework of the regional stratigraphy. The results of mammalian investigations and radiocarbon dating provide the basis for the stratigraphical subdivision. Palynology, mollusca, fishes, amphibian and reptiles are used for the reconstruction the palaeoenvironments. The Southern Urals stratigraphic subdivisions are correlated with Western European (Weichselian-Holocene), Eastern European (Russia) (Leningrad–Ostashkov–Shuvalov) and Uralian (Nevyansk–Polar Urals–Gorbunovsky) stratigraphic schemes.     

Development of the steppe zone in southern Russia based on the reconstruction from the loess-soil formation in the Don-Azov Region

Herbaceous communities in forest ecosystems on the southern part of the Russian Plain appeared in the Middle Miocene (??10 Ma BP). In the Late Miocene (??7 Ma BP), feather-grass steppe associations appeared among them. In the time span of 2.7 to 2.1 Ma BP (i.e., in the Early Quaternary, according to the current chronostratigraphic scale), the steppe zone arose on the southern Russian Plain in the Don-Azov Region. Seven stages of this zone development here have been distinguished throughout the Quaternary. The first one (Eopleistocene-Early Pleistocene) was characterized by savanna-like subtropic ecosystems. Then, in the Middle Pleistocene, the temperate zone ecosystems (tallgrass prairie-like steppes) developed here and were followed by steppe ecosystems close to the modern ones in Central Europe. The ecosystems of rich-species forb steppes developed in the Late Pleistocene. Finally, in the optimum of the modern interglacial (Holocene), steppes became similar to the modern ones here, but with a slightly higher precipitation. The general trend is characterized by reduction in heat and water provision and increase in aridization progressing from earlier to later stages.     

Position of the base of the Quaternary in West Siberia (based on paleobotanical and paleomagnetic evidence)

This study reviews a possible new position of the base of the Quaternary in West Siberia based on paleobotanical and paleomagnetic data in view of ratification of ICS recommendations by the IUGS Executive Committee and the decision of the Interdepartmental Commission on the Quaternary Stratigraphy of Russia to lower the base of the Quaternary (and, therefore, the base of the Pleistocene) at 2.58 Ma. The paleobotanical and paleomagnetic data from two horizons on the West Siberian plain (Kulunda, attributed in part to the formerly Neogene Gelasian Stage, and Kochki, attributed to the Quaternary) were used to identify global cooling that occurred synchronously with a regional cooling phase determined at the base of the Gelasian at Monte San Nicola, Italy.     

New data on the natural environment of the Middle and Late Neopleistocene interglacial periods in the east of the European Subarctic Region of Russia

The data obtained from investigation of the Middle and Late Neopleistocene lake sediments in the European Subarctic Region of Russia are reported. Chirva, Rodionovo (Scklov), Sula (Mikulino), and Byzovaya (Leningrad) sediments were subject to palynological analysis and investigation of particle size distribution and mineral composition. The spore–pollen spectra of the Chirva sediments demonstrate two climatic optima: the lower optimum is dominated by the pollen of Pinus sylvestris and broad-leaved species (up to 10%); the upper optimum is dominated by Picea sp. and Pinus sylvestris, while the pollen of Picea sect. Omorica and broad-leaved species are sporadic. The Rodionovo flora is characterized by a more xerophilous composition relative to the Chirva flora and a higher pollen content of pine, birch, wormseed plants, and wormwood. The climatic optimum of the Sula interglacial is distinguished by boreal vegetation, including spruce, birch, and birch–spruce forests with sparse broad-leaved species. The Byzovaya interstadial is marked by seven stages of changes in the vegetation: from tundra and forest-tundra communities to taiga forests with some broad-leaved species. The natural climatic sedimentation conditions in the Middle and Late Neopleistocene interglacial periods are reconstructed. The mineral composition of sediments was largely formed owing to underlying deposits.     

The first case study of 230Th/U and 14C dating of mid-valdai organic deposits

From the viewpoint of precision and reliability of radioisotopic dating, deposits whose quantitative age can be determined through several methods of geochronometry are of special interest. The mutually conforming finite ¹⁴C and ²³⁰Th/U dates of buried Neopleistocene organic deposits, taken from the Tolokonka section by the North Dvina River (100 km downstream from the city of Kotlas), have been obtained for the first time in Russia. The stratigraphical reference of these results to those obtained via the optically induced luminescence for upper and lower bedding layers has been established. The presented geochronometric data have allowed us to consider the age of oxbow lake organic deposits completely reliable and refer the time of their formation to the Tyrbei warming within the MIS-3. The applicability of the new version of the ²³⁰Th/U method for dating of interglacial and interstadial deposits, for the purpose of solving the Middle and Late Neopleistocene chronostratigraphy issues, is confirmed.     

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.     

Structure,composition, and depositional environments of recent sediments in the Upper Don River basin inferred from the Korostelevo section

The complex study carried out in the Upper Don River basin yielded comprehensive lithogeochemical, paleopedological, and paleontological data on recent sediments of the Korostelevo stratotype section. They provided grounds for the facies-genetic discrimination, subdivision, and correlation of the defined horizons based on paleopedological and paleontological data with the Neopleistocene time scale. The results made it possible to reconstruct environmental paleogeography for the early Neopleistocene-Holocene period and provided rhythmoclimatic substantiation of the stratigraphic subdivision of recent sediments in the study region.