Mln Years Research Articles

Structures and properties of the late pleistocene paleosols of the loess-soil section of Obi-Mazar (Tajikistan)

The loess-soil series of Central Asia cover the history of subaerial sedimentation of the last 2–2.5 mln years. Significant thicknesses, a large number of paleosols, and an impressive chronology place the loess-soil series of the Afghan-Tajik depression on a par with the famous sections of the Loess Plateau of China. The study of the most significant sections located within the Khovaling Loess Plateau makes it possible to develop a regional chronostratigraphic chart, to study the structure and conditions of formation of the main stratigraphic benchmarks–buried paleosols. The present study is devoted to the clarification of the structural features of loess and paleosols of the Late Pleistocene in one of the sections of the Khovaling–Obi-Mazar Plateau. Based on the results of stratigraphic dissection, description of the macro- and micromorphological structure, magnetic susceptibility analysis, study of the chemical and granulometric composition, a comprehensive description of the structure and properties was carried out and the most probable conditions for the formation of paleosols and loess were established. In the Late Pleistocene part of the section, two loess layers and a pedocomplex PC1 with three welded paleosols, consisting of a total of 7 horizons, are distinguished. The deposits are characterized by high silt content, carbon content, and the presence of signs of pedogenesis and biological activity in all layers of the studied section. Available data indicate the presence of a poorly developed MIS 3 paleosol in the upper loess layer. The developed pedocomplex PC1 of Obi-Mazar, according to its stratigraphic position, structural features, and magnetic susceptibility data, belongs to the MIS 5. According to preliminary data, its formation occurred in semi-humid and humid conditions under forest vegetation, which contributed to the biogenic segregation of Fe-Mn compounds, as well as intra- and interhorizon redistribution of carbonates due to diagenetic processes. Towards the end of the Last Interglacial, gradual aridization occurred, due to which the upper paleosol to be the least developed.

Early-Middle Acheulean Occupation of the Northern Transcaucasian Highland

In the northern part of the Transcaucasian Highland (Lori Depression, Armenia), three stratifi ed sites dating to the Early-Middle Acheulean—Karakhach, Kurtan I, and Muradovo—have long been subject to archaeological studies. On the basis of absolute dates and paleomagnetic records relating to the fi rst two sites, their age falls in the interval between the mid-Early and initial Middle Pleistocene. All three sites yielded a uniform industry with a peculiar toolset (various choppers, picks including chisel-ended ones, handaxes, large scrapers, macro-chisels, and macro-knives), manufactured mostly on natural tabular fragments of local volcanic rocks. Certain indicators of this industry, such as subrectangular and fan-shaped choppers, slab-like chisels, etc., are described. Information on 28 other localities with Acheulean artifacts, including 11 stratifi ed ones, recently discovered in various parts of the Lori Depression and in adjacent areas of the Shirak Depression and the Debed River valley, is provided. It is demonstrated that the lithics from all these sites belong to the Karakhach tradition. Data are cited suggesting that three sites (Yagdan, Agvi-canyon, and Agvorik) are over 2 mln years old, and two more (Kurtan II and Dzhradzor) are at least 1.5 mln years old. It is concluded that people associated with the Karakhach Acheulean tradition had appeared in the northern Transcaucasian Highland ~2.0 Ma BP, then settled widely in this area, and remained there for several hundred thousand years. In my view, this may be explained by the very favorable environmental conditions of the region during the Early Pleistocene, and by the abundance of large rock fragments suitable for tool manufacture.

On the Attribution of Lithic Industry from the Early Paleolithic Site of Bogatyri/Sinyaya Balka, the Taman Peninsula

The study describes and compares lithic artifacts from the Early Paleolithic site of Bogatyri/Sinyaya Balka, as well as those collected in coastal screes and on the nearby beach. Interdisciplinary studies, which have been ongoing at the site for more than 20 years, have made it possible to conclude that the age of the site exceeds 1 mln years, and that it was a butchering place. In the Early Pleistocene, a lacustral crater of a mud volcano was situated nearby. This mud marsh was a place where many large mammals such as Taman elephants and Caucasian elasmotheres bathed and perished. Humans procured them before they had drowned, and butchered them, as evidenced by the specifi c toolkit. The industry of the site is attributed to the Taman variety of the Oldowan stage of the Early Paleolithic. As the comparative analysis indicates, lithics from the screes and from the beach near the site are morphologically different from those at the site. The rocks of which they are made are of a higher quality, and the types are more expressive, which especially concerns cores and spalls. This industry should be attributed to the Taman variety of the Acheulean stage of the Early Paleolithic.

Про кузинську світу Мармароського покриву Українських Карпат

In 1957, L. G. Tkachuk and D. V. Gurzhiy have singled out the Upper Paleozoic Kuzian suite in the north-western part of the Marmarosh crystalline massif at the Rachiv area. It consists of phyllites, limestones, quartzites and dolomites. The suite is widely distributed in the Dilovets subcover of the Marmarosh nappe at the Rakhiv and Chyvchynian areas. There are two alternative points of view upon the age of the Kuzian suite. Some geologists attribute it to Paleozoic time (Upper Devonian-Lower Carboniferous), the others attribute its lower part to the Upper Paleozoic, and the upper one: to Triassic. One can notice the existence of the different estimation of the lithological composition and different estimation of the lithological composition and the volume of the Kuzian suite.Thus, in 1970 A. K. Boiko has devided it into Muntselulska (Lower) phyllite-quartzite one of Paleozoic age and Upper (Triassic) phyllite-carbonate one for which he saved the name Kuzian suite. The important is that a stratigraphic interruption was fixed between the above-mentioned units. The phyllite-carbonate Kuzian suite is dated on the basis of transgressive occurrence of the middle Triassic dolomites on it, discovery of the post-Paleozoic mosses in its lower part at the Soimul Mountain, and in the upper one: the complex of spores and pollen of Mesozoic age. Geologists, that do not recognize the idea of belonging of the part of suite to Mesozoic, indicate the next contradiction. If we accept the Mesozoic age of the Kuzian suite, so we must affirm that carbonate series of Middle Triassic-Jurassic were deposited on the massif at the same time, and 5–8 km southerly, the regional metamorphism of the Kuzian suite occurred within that zone (by the way, according to some facts at an interval of 148–178 and 175–181 mln years, and according to another information: at an interval of 196–221 mln years. This remark is not correct because the age of the Kuzian suite is Lower Triassic (251.9–247.2 mln years), but metamorphism occurred much later. In those sections where the Kuzian suite lies on the Muntselulska one, basal conglomerates consisting of pebbles and quartzitic fragments of underling suite are present in its bottom. Rocks of the Muntselulska and Kuzian suite are similar by their metamorphism intensity. For the Mesozoic Kuzian suite the manifestations of the main magmatism are characteristic, unlike the Upper Paleozoic acids. The facts testify to that the Mesozoic Kusian suite is existing, but there is a certain indefinity as to its finer dividing, stratigraphic volume and correlation with deposits of Middle Triassic. To avoid confusion, it is expedient to alter the name of the Mesozoic Kuzian suite and to name it, for example, Neo-Kuzian.

Evolution of the Lithic Industry in Central Dagestan During the Early Pleistocene: The Rising Occurrence of Flake Blanks

Archaeological data from stratified Early Pleistocene sites in Central Dagestan are arranged in a direct stratigraphic sequence, making it possible to reconstruct the changes in lithic industry over a span of 1.2 mln years, from ~2.0 to 0.8 Ma BP, and to separate the principal stages in the Early Paleolithic culture of the Caucasus. This study examines blanks found at sites of the Ainikab-Mukhkay group, such as Ainikab-1, and Mukhkay-1, -2, and -2a. Occurrences of large flake blanks (>10 cm) at the Oldowan and the Oldowan to Acheulean transitional stage are provided. Such blanks appear at the beginning of the Jaramillo paleomagnetic episode (~1.07 Ma BP). By the end of the Early Pleistocene, their share attains 25.77 % of the total number of blanks for morphologically distinct tools. They are absent in Oldowan deposits (~2 Ma BP). The totality of statistical data justifies the separation of the transitional Oldowan to Acheulean stage in the region, dating to 1.0–0.8 Ma BP.

Comparison of Tectonic Phases and Geomagnetic Reversals in the Late Mesozoic and in the Cenozoic

The authors consider the chronological relation of two groups of phenomena in the history of the Earth over the last 150 mln years. One of them is relatively short (a few million years) tectonic phases, or orogenic phases, identified by H.W. Stille in 1924 and characterized by an increase in compressive deformation in mobile belts of the Earth. Deformations that occur during such phases are quite explicable by collisional interactions of lithospheric plates. However, these interactions do not explain the synchronous occurrence of phases in different belts and on different continents. The other group is the frequency of magnetic reversals, i.e., changes such that the positions of magnetic north and magnetic south are interchanged. Tectonic phases are more frequent in epochs of frequent geomagnetic reversals. During the last 24 mln years, when geomagnetic reversals were especially numerous, tectonic phases came one after another in short intervals. An emerging trend for them is the lagging of phase peaks by one to two million years relative to the most frequent magnetic reversals. The chronological relations identified show that tectonic phases are determined not only by geodynamic processes in the lithosphere but also by the action of energy pulses that occur in the Earth’s core and at the boundary of the core with the mantle, where the Earth’s magnetic field is generated. On the geological time scale, this interaction takes place quickly, which excludes energy pulse convection and prompts the search for other mechanisms of this transfer. It is possible that it takes place because the lithosphere is affected by alternating body forces that occur under a change in currents in the core, which is followed by changes in the mode of the Earth’s rotation and the adaptation to it of lithospheric masses.

Faunas of Small Mammals of the First Half of the Middle Pleistocene in Europe

The main evolutionary stages of formation of the faunas of small mammals of the Middle Pleistocene in Europe, belonging to the interval ~0.76−0.42 mln years, are described. Based on the analysis of the species composition of the faunas of this interval, six main phases of development of small mammals, corresponding to the main climatic events (interglacials, glaciations) during MIS 18 – MIS 12 are identified. Availability of data for some intervals of the first half of the Middle Pleistocene is not too large. Especially this applies to the cold stages of the first half of the Middle Pleistocene – the Don and Oka (or, that is the same, the Elster and Anglian) glaciations. In several cases the difference in time of the appearance of a number of taxa in Eastern and Western Europe was revealed. So, Arvicola cantianus appeared in Western Europe earlier than in Eastern Europe. This phenomenon can be explained by different rates of evolution in different parts of Europe, and, possibly, insufficient number of related data (geological, geochronological, and paleontological), which subsequently allow to determine the age of a number of localities. The analysis of correlation of the East European and West European faunas of small mammals was carried out. The biostratigraphic scheme and the map of localities of small mammals of the Middle Pleistocene during MIS 18 – MIS 12, i.e. in the first half of the Middle Pleistocene on the international scale (early Neopleistocene according to the scale RISK), were built. The obtained data allows to substantiate more accurately and to clarify the geological age of the deposits, and to reconstruct the palaeogeographical setting of the considered periods. They are also an important component in the establishment of biostratigraphic schemes of the Middle Pleistocene and the Pleistocene in general.

European small mammal fauna during the end of early – the beginning of middle pleistocene

The evolutional changes of European small mammal fauna (mostly Arvicolidae) during Early Pleistocene – Middle Pleistocene transition were analyzed. The fauna between the beginning of the Jaramillo palaeomagnetic event till the Ilinka interglacial of Middle Pleistocene were taken into account (1.07– 0.7 mln years ago). The principal trends in small mammal evolution were revealed. The comparison between the Eastern European fauna and Western European one was carried out.

Host associations and origin in the formation of the Caucasian fauna of fleas (Siphonaptera)

Results of analysis of the Caucasian fauna of fleas and their association with mammal and avian hosts are reported. The Caucasian fauna of potential flea hosts comprises about 130 species of mammals and about 470 species of birds. Most of the flea species in the Caucasian fauna (88 out of 155) parasitize rodents, 51 species of which are permanent hosts of different flea species; 13 flea species occur on 11 species of insectivores; 13 flea species, on 13 species of chiropterans; 14 flea species, on 20 species of carnivores. Only 2 flea species parasitize artiodactyles. 54 species of birds are permanent hosts of 23 species of fleas from 4 genera in the Caucasus. Ten types of ranges of flea species are distinguished; host associations of the Caucasian flea species from these groups are discussed. The greatest numbers of hosts from the families Cricetidae, Muridae, and Sciuridae are associated with fleas with Euro-Asian (extra-Siberian), European, Turanian, and Iranian ranges. Soricidae are known as hosts of flea species with European and Euro-Turanian ranges. Four major groups of flea taxa are represented in the Caucasian fauna. The distribution of the first group is determined by the influence of the palaeofauna of the ancient European continent in the early Cenozoic; that of the second group, by the influence of the fauna of the ancient Asian continent during the Paleogene and part of the Neogene; the third, by the influence of the fauna of southern Europe starting with the Miocene. The fourth group comprises the species which immigrated from northern Europe and Asia in the Late Neogene (2–3 mln years ago).

Phylogenetic relationships of silver crucian carp in Carassius auratus complex based on mtDNA analysis

The phylogenetic relationships of Carassius genus subspecies were investigated based on the data of the variability of nucleotide sequences of the mtDNA cytochrome b (cyt b) and control region (CR). Dendrograms constructed based on the BA, ML, NJ, and MP methods revealed five clusters of the congruent topologies that substantially corresponded to geographical localities and taxonomic conception of the C. auratus complex. An analysis of two mtDNA fragment topologies demonstrated that the island forms of Japanese crucian carps C. cuvieri and C. auratus langsdorfii diverged later compared to the divergence of continental C. auratus forms (4.0-4.5 mln years ago, by molecular calibration). Among the continental silver crucian carps, C. a. gibelio forms two clusters corresponding to two phylogroups with a mean uncorrected genetic distance p = 0.044. The genealogical combination of haplotypes with the first C. a. gibelio phylogroup was observed in C. auratus clade. According to the data of mtDNA analysis, these subspecies represent sister lineages with a level of intergroup divergence of p = 0.022-0.036. No genetic differences were observed between diploid (except for the two C. a. gibelio phylogroups) and polyploid C a. auratus, as well as monophyly in polyploid forms. New approaches based on a comparative study of the nuclear markers might help to unravel the origin of gynogenetic forms and phylogenetic relationships within the C. auratus complex.

A New 190Pt-4He method of native platinum age determination

A new method of determining the age of native platinum based on alpha-radioactivity of one of its natural isotopes 190Pt is proposed. Due to a special form of occurrence of radiogenic helium in the crystal lattice of native metals as a helium cluster-bubbles, the stability of 190Pt-4He of the isotope system is extremely high in the natural environment. To check the efficiency of the proposed 190Pt-4He method of isotope geochronology, six independent mineral aggregates of native platinum from chromite-bearing dunites of the southern part of platinum-bearing zonal Galmoenan dunite-cllinopyroxenite-gabbro plutonic complex (Koryak-Kamchatka belt, Russia) were analyzed. The age calculated by the tangent of the 190Pt-4He isochrone slope angle equals 69.5 ± 4.9 mln years. The obtained age value coincides with the results of isotope datings, which were made previously by different methods of isotope geochronology.

Metamorphic core complexes of the Transbaikalia: review

Metamorphic core complexes (hereafter MCC) revealed in the Transbaikalia have similar features of their patterns. Three levels can be distinguished by structural­material indicators: core, zone of mylonites (dynamically metamorphosed rocks) and overlying formations. The cores are composed of the Paleozoic granites and granitogneisses. Zones of mylonites skirt the cores and are characterized by various tectonites which are formed at the expense of the core rocks. The overlying formations include volcanogenic­sedimentary series of the Mesozoic and the Upper Palaeozoic. The rocks are not metamorphosed, yet subject to brittle deformations. Structurally, they are detached and deposited above the zone of mylonites. In Transbaikalia, MCC are characterized by synmetamorphic structural paragenesises of one type: low­angle schistosity, micro­ and macro­structures (folds, mineral streaking, boudinage, pressure shadows, C–S structure, kick­bends). According to the kinematic analyses, they were formed by the simple shear mechanism along the zones of deeply penetrating regional dislocations which plunged in the south­eastward direction. Tectonic transportation of the materials developed in the same direction, i.e. the top parts of tectono­stratigraphic sections were displaced against the lower parts in the south­eastward direction. Extension deformations tended in the north­west – south­east direction. Such movements facilitated formation of synthetic listric normal faults and rift basins. The most intensive tectonic exposure period is determined as 112–123 mln years, while the period of metamorphism is assessed as 140–130 mln years. The rocks in depth of the deep dislocation were transformed in conditions of amphibole facies of metamorphism (Т=590–640 °С; Р=3.2–4.6 kbar). According to our structural-­geological, petrological and isotopic data, the age of the majority of the metamorphic formations of the Transbaikalia is determined as the Late Mesozoic. They were formed in the extension regime due collapse of the Late Mesozoic orogeny, that was caused by accretion­collision events during the Early Mesozoic. Thickening of the continental crust contributed to increase of heat flow and higher plasticity at the crustal bottom. The orogen was thus unstable and flowing and caused regional extension and dislocations at the middle­crust level. Thinning of the crust was accompanied by isostatic uplifting which facilitated emergence of the structural metamorphic complexes of the middle­crust levels on the surface and formation of the metamorphic core complexes.

U-Pb (SIMS SHRIMP-II) age of volcanic rocks from the Tulukuev caldera (Streltsov Uranium-Ore Cluster, Eastern Transbaikalia)

The precision dating (U-Pb local by zircons, SHRIMP-II) of volcanic rocks in the unique uranium-bearing structure of Transbaikalia is performed for the first time. The basic conclusions are as follows. The volcanic activity in the Tulukuev caldera covers the period of not less than 30–35 mln years, within the period from (not later than) 162 to 128 mln years. Two stages of caldera evolution are established: the early (trachydacite-basalt) stage up to 154 mln years and the late (trachybasalt-rhyolite) stage from 142 to 128 mln years, with a 10 mln year break, which caused the deep erosion of the lower layer. Three phases of rhyolite magmatism are substantiated. The first one, 142 mln years, is the ejection of ignimbrites (microfelsitic rhyolites); the second one, 137–135 mln years, is the outflow of lavas of sanidine-morion rhyolites and subvolcanic and ring dyke intrusions. The third phase, 128 mln years, is connected with the occurrence of cesium-bearing perlites in the southwestern part of the caldera. The age of the granite-porphyries of the Krasnokamensk stock almost coincides with the precision data of the age of the uranium ores [4]. It is found that zircons from the granite-porphyries within the ore field of the Argunsk deposit have an anomalously high content of uranium. This fact can additionally testify to the time-and-spatial closeness of magmatism and processes of ore formation.

The volumes of volcanic seamounts as a factor determining the formation of the ocean floor’s morphostructure

The volumes of formed volcanoes are an important indicator of the formation intensity of the ocean floor volcanogenic morphostructure under different geodynamic conditions. The distribution of the volumes of volcanoes that formed within the oceanic lithosphere of different geological ages is considered to analyze the spatial and time dynamics of the scopes of the seamount formation. The greatest volumes of effused rocks concentrate in volcanoes of different heights on the different-age segments of the lithosphere. The total volumes of volcanogenic substance growing with increasing age and thickness of the lithosphere is caused by the increasing range of the heights of the formed volcanoes and the growing number of big seamounts. Despite that the volcanic seamounts formed within the mid-oceanic ridges, on the divergent boundaries of the lithospheric plates and in the transform faults most often, half of the volcanogenic material was emitted to the earth’s surface during the spreading of the intraplate volcanism. A leading part in the formation of the volcanogenic morphostructure of the ocean floor belongs to the formation of big seamounts with heights of 4–6 km and volumes from 1500 to 5100 km3, respectively, in the provinces with ages from 60 to 90 mln years.

The southern fragment of the Siberian craton: "landscape" history over two billion years

The southern fragment of the Siberian craton: "landscape" history over two billion years

Heart transcriptome of the bank vole (Myodes glareolus): towards understanding the evolutionary variation in metabolic rate

BackgroundUnderstanding the genetic basis of adaptive changes has been a major goal of evolutionary biology. In complex organisms without sequenced genomes, de novo transcriptome assembly using a longer read sequencing technology followed by expression profiling using short reads is likely to provide comprehensive identification of adaptive variation at the expression level and sequence polymorphisms in coding regions. We performed sequencing and de novo assembly of the bank vole heart transcriptome in lines selected for high metabolism and unselected controls.ResultsA single 454 Titanium run produced over million reads, which were assembled into 63,581 contigs. Searches against the SwissProt protein database and the ENSEMBL collection of mouse transcripts detected similarity to 11,181 and 14,051 genes, respectively. As judged by the representation of genes from the heart-related Gene Ontology categories and UniGenes detected in the mouse heart, our detection of the genes expressed in the heart was nearly complete (> 95% and almost 90% respectively). On average, 38.7% of the transcript length was covered by our sequences, with notably higher (45.0%) coverage of coding regions than of untranslated regions (24.5% of 5' and 32.7% of 3'UTRs). Lower sequence conservation between mouse and bank vole in untranslated regions was found to be partially responsible for poorer UTR representation. Our data might suggest a widespread transcription from noncoding genomic regions, a finding not reported in previous studies regarding transcriptomes in non-model organisms. We also identified over 19 thousand putative single nucleotide polymorphisms (SNPs). A much higher fraction of the SNPs than expected by chance exhibited variant frequency differences between selection regimes.ConclusionLonger reads and higher sequence yield per run provided by the 454 Titanium technology in comparison to earlier generations of pyrosequencing proved beneficial for the quality of assembly. An almost full representation of genes known to be expressed in the mouse heart was identified. Usage of the extensive genomic resources available for the house mouse, a moderately (20-40 mln years) divergent relative of the voles, enabled a comprehensive assessment of the transcript completeness. Transcript sequences generated in the present study allowed the identification of candidate SNPs associated with divergence of selection lines and constitute a valuable permanent resource forming a foundation for RNAseq experiments aiming at detection of adaptive changes both at the level of gene expression and sequence variants, that would facilitate studies of the genetic basis of evolutionary divergence.

History and Causes of Variations in the Caspian Sea Level: the Miopliocene, 7.1–1.95 Million Years Ago

It is shown that the awareness of the regularities and causes of variations in the Caspian Sea level from the moment of its origin as an isolated lake basin in the Late Miocene (7.2 mln years ago) is of great importance for paleohydrology. Out of the seven principal hydrologic stages of the Caspian Sea history, four stages are considered in this paper: two lake stages (the Late Miocene and Middle Pliocene), the intermediate stage when the Caspian and Zanklinian basins were connected, and the stage of the Manych runoff. An important fact in the Caspian Sea history is emphasized: penetration of the Akchagylian fauna forebears into the Caspian Sea Basin through the Black Sea and the nowadays nonexistent Kuban–Terek Channel (between 5.3 and 3.3 mln years ago). Three phases of penetration of the Mediterranean Zanklinian fauna into the Caspian Basin are recognized. The channel became “closed” during the Middle Pliocene phase of the Great Caucasian Range elevation (3.3–2.5 mln years ago). This isolation of the Caspian Basin caused the formation of the Great Akchagylian Lake. Its water washed out the New Manych Channel 2.5 mln years ago. From this moment on, the events that occurred in the Caspian Basin and in the Black and Mediterranean seas can be correlated in greater detail, “link by link”, within the 413-thousand-year period of water abundance.