Plio-Pleistocene geological record and small mammal faunas, eastern shore of the Azov Sea, Southern European Russia

The shoreline of the Taganrog Gulf of the Azov Sea at the mouth of Don River provides a series of extended Upper Pliocene and Quaternary sections that have been actively studied in the last century. This extraglacial region had a complex sedimentary history combining subaerial aggradation with marine, fluvial, and deltaic sedimentation. The well-exposed stratigraphical sequence and abundant palaeontological record continuously attract geologists and highlight the region as one of international importance for the addressing of numerous problems of Late Pliocene and Quaternary stratigraphy and palaeogeography. Fossil mammalian faunas of the region include important Eurasian biostratigraphical markers such as Stenocranius ex gr. hintoni-gregaloides, Lagurini spp., and Mimomys savini. For many years, fossil remains of mammals provide decisive clues to the geological history of the region. Recent geological studies of reference sections have provided data on small mammals, palaeomagnetism and palaeogeographical reconstructions in the northeastern part of the Azovian Region. Mammalian assemblages indicate the presence of the Late Pliocene, late Early Pleistocene, Middle Pleistocene and Late Pleistocene levels and, in addition, provide a clear biostratigraphical context for the Early Middle Pleistocene transition.     

Quaternary tectonics of recent basins in northwestern Armenia

New data on the stratigraphy, faults, and formation history of lower to middle Pleistocene rocks in Late Cenozoic basins of northwestern Armenia are presented. It has been established that the low-mountain topography created by tectonic movements and volcanic activity existed in the region by the onset of the Pleistocene. The manifestations of two geodynamic structure-forming factors became clear in Pleistocene: (i) collisional interaction of plates due to near-meridional compression and (ii) deep tectogenesis and magma formation expressed in the distribution of vertical movements and volcanism. The general uplift of the territory, which was also related to deep processes, reached 350–500 m in basins and 600–800 m in mountain ranges over the last 0.5 Ma. The early Pleistocene (~1.8 Ma) low- and medium-mountain topography has been reconstructed by subtraction of the latest deformations and uplift of the territory. Ancient human ancestry appeared at that time.     

Maeotian mammalian localities of Eastern Paratethys: Magnetochronology and position in European continental scales

The Maeotian of Eastern Paratethys corresponds to the interval of the magnetochronological scale from the base of the subchron C4Ar2n to upper parts of the Chron C4n (9.6–7.5 Ma). Fission-track dates of Maeotian deposits are in general agreement with paleomagnetic chronology. In the continental stratigraphic scale of Western Europe this interval corresponds to zones MN10 (save the lowermost parts), MN11, and MN12 (upper part). Taking into account age estimates of MN zones boundaries established in Western Europe, the East European mammalian localities of Ukraine and Moldova can be stratified as follows: MN10, Raspopeni, Grebeniki, Novaya Emetovka 1, ?lower bed of Ciobruci; MN11, Novaya Emetovka 2; MN12, Cimislia, Ciobruci upper bed, Cherevichnoe, Tudorovo, Dzedzvtakhevi, and sites in the lower Pontian deposits. The faunal criteria used to distinguish MN zones in Western Europe cannot be completely applied to sites of the Eastern Paratethys because of paleozoogeographic distinctions between West and East European provinces. Specific criteria of zone boundaries definitions should be developed for the East European province.     

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.     

Structural specificity of pleistocene loess and soil formation of the southern Russian plain according to materials of Eastern Priazovie

Doklady Earth Sciences -     

Age of the Vallesian lower boundary (Continental Miocene of Europe)

The Vallesian lower boundary and “Hipparion-datum” are estimated as ranging in age from 11.2 to 10.7 Ma in Central to Western Europe and Western Asia. Judging from complete sections of Sarmatian marine sediments in the Tamanskii Peninsula and Transcaucasia with known paleomagnetic characteristics, the above dates correspond to the lower upper Sarmatian (Khersonian) of the Eastern Paratethys, although in Moldova and Ukraine the earliest hipparion remains are associated with the middle Sarmatian (Bessarabian) sediments. The normally magnetized middle Sarmatian deposits in hipparion localities of Moldova are correlative with an upper part of Chron C5An (upper boundary 11.9 Ma old) or, less likely, with Subchron C5r2n (base 11.5 Ma old). Consequently, the first occurrence of hipparions in southeastern Europe is recorded in the Middle Miocene, i.e., 0.7 m.y. (or 0.3 m.y.) earlier than the date of 11.2 Ma formerly accepted for the Vallesian lower boundary in Europe. Possible reasons for disagreements in age determination of the Vallesian base are discussed.     

Late Sarmatian mammal localities of the Eastern Paratethys: Stratigraphic position,magnetochronology, and correlation with the European continental scale

Analysis of geological sections, paleogeography, and paleomagnetic data is used to reveal succession of the middle to late Sarmatian mammal localities of the Eastern Paratethys and their correlation with the continental stratigraphic scale of Western Europe. Until recently, the late Sarmatian localities were correlated with MN10 and even MN11 zones. As is proved, all the known late Sarmatian localities should be correlated with the upper half of Zone MN9. The terminal late Sarmatian faunas only, which are correlative with the lowermost Chron C4Ar3r and older than 9.6 Ma, can be referred to Zone MN10. According to essential changes in taxonomic composition of faunas from continental localities around the Eastern Paratethys, which are recorded in the mid-late Sarmatian, Zone MN9 can be divided in two subzones MN9a and MN9b separated by boundary at ～10.5 Ma. The refined correlation can be used to establish difference between faunas of the Southeastern, Central, and West European paleozoogeographic provinces and to assess diachronism in dispersal of mammals. In the Southeastern province, many forms characteristic of the Turolian in Central and Western Europe first appeared as early as in the mid-Vallesian. The results obtained indicate that faunal criteria used to define boundaries of MN zones in Western Europe are of a regional importance being inapplicable to the entire North Eurasia and even to Europe as a whole that is unfortunately ignored by many paleontologists. Criteria of distinction should be worked out for each paleozoogeographic province. As geochronological levels of faunal changes are identical throughout the northern Palearctic, they suggest impact of global factors despite variable manifestation in different regions.     

Reconstruction of Late Pleistocene events in the periglacial area in the southern part of the East European Plain

An integrated study of the loess–soil sequence in the coastal exposure near the settlement of Beglitsa (Rostov oblast) allowed us, for the first time, to reconstruct the landscape-climatic changes that occurred in the eastern Azov region over the course of the Late Pleistocene. In the south of the periglacial zone, considerable differences between intensity of the loess accumulation in the Early and Late Valdai Cryochrons were revealed. In the Early Valdai Epoch, which corresponds roughly to the end of Marine Isotope Stage (MIS) 5 and MIS 4, loess accumulation occurred after completion of development of the Mezin pedocomplex and before the beginning of the Bryansk stage of soil development, i.e., over more than 20 000 years. In the much shorter Late Valdai Cryochron MIS 2 (10 000–12 000 years), loess accumulation reached 5 m. The data evaluation shows that the loess accumulation rates in the Early Valdai Epoch (~0.07 mm/year) and the Late Valdai Epoch (~0.5 mm/year) differ from each other by an order of magnitude.