A complicated tectonic and sedimentation history of the high-mountainous south-eastern part of Russian Altai predetermined the presence of sources of ancient organic matter in the region. During the Pleistocene these deposits were affected by various exogenous processes that leads to mixing of young and old carbon in a unique (for each sample) ratio and strongly affects the results of radiocarbon dating. This paper presents the results of multidisciplinary investigations of pedosedimentary sequences and discusses C-14 dating of heterochronous organic matter in paleosols of two locations within the Chuya basin in the chronological context of the late Pleistocene megafloods. In the Kamsug valley reasonable evidence of the oldest (Pleistocene) paleosols in the SE Altai is described for the first time. The mineral composition of sediments and the results of pollen analysis argue for a short-distant redeposition of the Paleogene-Neogene parental substrate. Later it was transformed by Pleistocene pedogenesis: cryogenic processes, particularly solifluction, redox fluctuations resulted in redistribution of Fe and Mn. The analysis of available radiocarbon dates indicates that the contamination of the samples by extraneous carbon and the insufficient data about the features of organic matter of the studied soils don't allow to draw a definite conclusion about the time of the Pleistocene pedogenesis in the region. The presented OSL age 37.0 +/- 3.1 ka (GdTL 3424) predates pedogenesis in this location, as well as the last ice-dammed lake formation in the Chuya basin and its further cataclysmic draining followed by the deposition of cross-bedded gravels and pebbles. In the neighbouring Yamanterek valley radiocarbon dating result for paleosol returns erratic (aged) date due to the influx of ancient organic matter. Similarly, this date cannot serve as the upper chronological limit of ice-dammed lakes existence in the Chuya depression. The radiocarbon ages (9.7-11.3 ka cal BP) of charcoals from the underlying lens of humus sands postdate the last ice-dammed lake with the water level at least 1980 m a.s.l. It was demonstrated that short-distant redeposition of the Paleogene-Neogene sediments in the region preserves their main mineralogical and paleontological features. It gives an opportunity to recognise such redeposited sediments which contain geological carbon. Meanwhile the redeposition followed by pedogenesis introduces younger organic matter. Diagenesis of such originally different organic matter contributes the final pool of organic carbon and results in the formation of heterogenous and heterochronous organic matter. This should be taken into account while 14C dating and interpreting the obtained results.

Представлены результаты палинологического и микропалеонтологического изучения верхнемеловых–кайнозойских толщ, вскрытых скважинами 23 и 19 Алейской площади (Алтайский край). Полученные данные позволили обосновать возраст отложений, высказать предположения об условиях их формирования, уточнить расчленение разреза на свиты. В меловой части разреза скв. 23 установлены два палинокомплекса: первый характеризует леньковскую свиту и датируется сеноманом–туроном; второй выявлен в верхнесымской подсвите и датируется маастрихтом. На верхнемеловых отложениях залегает палеогеновая островновская свита континентального генезиса. В скв. 19 и 23 эта свита содержит спорово-пыльцевые спектры предположительно позднепалеоценового–раннеэоценового и среднеэоценового возраста соответственно. По палинологическим данным обоснован позднемиоценовый возраст отложений верхней части разреза скв. 23 и их принадлежность к павлодарской свите. Структура палинологических комплексов, особенности мацерата, отсутствие фораминифер указывают на континентальный генезис верхнемеловых–палеогеновых отложений, распространенных в южной части Кулундинской впадины Алтайского края.

В ходе экспедиционных работ летом 2018 г. в дельте р. Лены на о. Сардах-Сисе были обнаружены отпечатки листовой флоры, принадлежащие видам широко- и мелколиственных листопадных деревьев. Обнаруженные нами отпечатки приурочены к слою ожелезнённых песчаников в основании разреза о. Сардах-Сисе. Были установлены следующие таксоны: Platanus sp., Alnus sp., Fagus sp., Salix sp. Кроме того, был найден окаменелый плод, принадлежащий Magnolia sp. Сделанные находки позволяют сделать вывод о существовании в раннем-среднем миоцене в данном районе смешанных лесов, состоящих из хвойных, мелко- и широколиственных листопадных видов деревьев и кустарников.

The results of palynological and micropaleontological study of Upper CretaceousCenozoic strata exposed by boreholes (BH) 23 and 19 of the Aleisk Square (Altai Region) are presented. The obtained data allowed to substantiate the age of deposits, to make assumption about its depositional conditions and to clarify the division of the section into suites. Two palynological assemblages were established in the Cretaceous part of the BH 23 section: the first characterizes the Lenki Formation and dates by SenomanianTuronian, the second one is revealed in the Upper-Sym Subformation and dates by the Maastrichtian. The Paleogene Ostrovnoye Formation of continental genesis lies on the Upper Cretaceous sediments. In BH 23 and BH 19, this formation contains spore and pollen spectra of presumably Late PaleoceneEarly Eocene and Middle Eocene age respectively. According to palynological data, the Late Miocene age of the sediments at the upper part of BH 23 section and its affiliation to Pavlodar Formation have been substantiated. The structure of palynological assemblages, features of macerate and the absence of foraminifera indicate the continental genesis of the Upper CretaceousPaleogene sediments common in the southern part of the Kulunda Depression of the Altai Region.

Paleoenvironmenal reconstructions have been made from a multidisciplinary study of a borehole permafrost record on Kurungnakh Island (Lena delta). According to data on palynomorphs and ostracods, the clay silt units from the 10.58 to 13.54 m and 1.58 to 10.3 m core depth intervals were deposited in the Late Pleistocene (during the Karginian interstadial) and Early-Middle Holocene, respectively. The sediments were studied in terms of moisture contents, grain size distribution, mineralogy, and magnetic susceptibility, and the results were compared with published evidence from nearby natural outcrops. Quite a cold oligotrophic lake existed in the area during the Karginian period, and the deposition was interrupted by a gap recorded at a core depth of about 11 m. In the Early and Middle Holocene, the area was covered with shrub tundra vegetation.

The first findings of well-preserved foliar flora (Platanus sp., Alnus sp., Fagus sp., Salix sp., and Magnolia sp.) have been recovered from the Late Cenozoic (Neogene) deposits on Sardakh-Sise Island, in the Lena River delta. The findings, which also include remains of coniferous wood, are hosted in ferruginized sandstones at the base of the section. The floral composition suggests that mixed forests incorporating coniferous, broad- and small-leaved deciduous trees, and shrubs (moderate and subtropical thermophytes) grew in this area. The deposits contain foliar flora could forms in the Early–Middle Miocene, not in the Pliocene as is presently believed. Most likely, the basal conglomerates and sandstones of the Sardakh-Sise Island section refer to the Urasalakh Fm. The finding site of Neogene foliar flora on Sardakh-Sise Island is now the northernmost location in Eurasia.

During the field works in the summer of 2018, in the Lena River delta on the Sardakh-Sisse Island, prints of leaf flora belonging to species of broad and small-leaved deciduous trees were found. The prints found by us are confined to the layer of ferruginous sandstones at the base of the section. The following taxa established: Platanus sp., Alnus sp., Fagus sp., Salix sp. In addition, a fossilized fruit belonging to Magnolia sp. The findings allow to conclude that there are mixed forests in the early-middle Miocene in this region, consisting of coniferous, small- and broad-leaved deciduous species of trees and shrubs.

For the first time some outcrops of the Upper Miocene Ishim Formation on the south of Tyumen Area near Pyatkovo, Masali and Bigila villages are studied by palynological method in detail. A series of mineralogical analyzes of these sediments and radiocarbon analysis of the Quaternary sediments overlying the Ishim Formation are done. Four palynocomplexes (PC) are established in the Ishim Formation: PC1 with Botryococcus; PC2 with Botryococcus, Sigmopollis; PC3 with Alnus, Polypodiaceae, Botryococcus, Sigmopollis; PC4 with Betula, Alnus, Corylus. The layers with PC1, PC2 и PC3 are traced in two outcrops near Masali and Bigila Villages. PC4 is revealed from the sands and aleuropelits of the outcrop near Pyatkovo Village, it is characterized by a significant content of diverse pollen of temperate termophylic broad-leafed taxa and by the presence of rare typical Miocene elements (Таxodiaceae, Nyssa, Tsuga). The PC3 and PC4 are compared with the complexes well known from the Neogene sediments of Western Siberia. PC5 with Betula, Herbae, Fungi is revealed from the bedded silts overlying the Ishim Formation in Masali outcrop. Previously, these sediments were attributed to the Late Miocene Pavlodar Formation. The composition and the structure of PC5 allowed making an assumption about Quaternary age of the enclosing sediments. Radiocarbon analysis of the organic substance from the silts showed, that these sediments were accumulated in the Late Pleistocene (Sartan Ice Age). For the first time the information about microphytoplankton (Botryococcus, Pediastrum, Zygnemataceae, Sigmopollis) and other nonpollen palynomorphs, contained in Ishim Formation (Upper Miocene) and in Pleistocene sediments, is given. On palynological data, some stages of development of the Late Miocene Ishim Basin and the type of vegetation surrounding this basin are considered. The depositional environment of Pleistocene sediments (Masali outcrop) is reconstructed.

This paper presents the results of multidisciplinary investigations of the peat-bed under hummocky permafrosted boggy meadow within the Boguty basin. For the last 7600 years 4 evolutionary phases of peatbog formation within the drained part of Low Boguty Lake bottom were established and corresponding 4 pollen complexes were described. 18 radiocarbon dates suggest some chronological bench marks of postglacial landscape evolution in the region. After degradation of Sartan glaciation about 14000 BP, trees grew in now forestless areas at 11000 BP and 8500-7800 BP. The climate in the first half of the Holocene was warmer and more humid. Accumulation of lacustrine loams within the studied peatbog occurred before 7600 BP with predominated algae Pediastrum, Zygnemataceae and Botryococcus. After the lake level lowered in the result of destructing moraine dam, two lower peat horizons were developed about 7600 - 7200 BP. An episode of significant lake desiccation (later than 7200 BP) was recorded in all proxy archives. Further rise of water supply led to increasing the number of water-bog plants, diatomaceous, euglenic and green algae. At the same time, the pollen of xerophytes began to predominate in the pollen complexes, indicating aridization. The final stage reflects stable peatbog drying and its transformation into boggy meadow, decomposition and mineralization of peat.

Results of complex paleontological and geochemical analysis are reported for a new locality of the Upper Oligocene–Lower Miocene Kosh-Agach carbonaceous formation in the Dzhazator River valley. This find specifies the scales of lacustrine–marsh sedimentation at the end of the Paleogene and beginning of the Neogene, as well as the character and amplitude of post-Neogene neotectonic movements in the southeastern highest mountain part of Russian Altai. Systematic rejuvenation of the radiocarbon age of the sequences studied, which has been established for the first time in Altai, is related to influx of young carbon during the subsequent complex geological history. This fact is of great importance for deciphering the chronology of Pleistocene glacial–dammed lakes in the intermontane basins of Altai and Tuva, the erosion zone of which spanned exhumed Tertiary deposits.

The results of complex palynological and microfaunistic studies of Upper Cretaceous and Cenozoic deposits of the Bakchar iron ore deposit are presented. Geochronologically, the age of the deposits varies from Campanian to Quaternary. It was established that the Slavgorod, Gan’kino, and Jurki (?) formations contain four biostratons in the rank of beds with dinocysts and three biostratons in the rank of beds with spores and pollen. The Cenozoic continental deposits contain four biostratons in the rank of beds, containing spores and pollen. As a result of the study, a large stratigraphic gap in the Cretaceous–Paleogene boundary deposits, covering a significant part of the Maastrichtian, Paleocene, Ypresian, and Lutetian stages of the Eocene, was established. The remnants of a new morphotype of heteromorphic ammonites of genus Baculites were first described in deposits of the Slavgorod Formation (preliminarily, upper Campanian). The distribution features of the different palynomorph groups in the Upper Cretaceous–Cenozoic deposits in the area of study due to transgressive-regressive cycles and climate fluctuations were revealed.

New micropaleontological and paleomagnetic data were obtained by studying core samples of Cenozoic continental deposits from two boreholes drilled in the south of Tyumen oblast (Western Siberia). Palynological assemblages in deposits of the Tavda (upper part), Novomikhailovka, Turtas, Abrosimovka, Tobolsk, Smirnovka, and Suzgun formations were described. Deposits of these formations are enriched in spore-pollen assemblages, which can be correlated with assemblages of regional palynozones of the West Siberian Plain. Ostracods were described in Quaternary deposits. On the basis of biostratigraphic and paleomagnetic data, the Late Eocene (Priabonian)–Holocene age of deposits was substantiated. For the first time, beds with dinocysts of genus Pseudokomewuia were identified in deposits of the Turtas Formation (Upper Oligocene) of the Ishim lithofacial area. In total, nine regional magnetozones were distinguished in the paleomagnetic section. On the basis of palynological and paleomagnetic data, sections of two boreholes were correlated, and hiatuses in sedimentation were revealed. A large hiatus is at the Eocene-Oligocene boundary (Western Siberia): the Lower Oligocene Atlym Horizon and Miocene–Pliocene and Eopleistocene sediments are missing. The Oligocene interval of the section is represented in a reduced volume.

An extraordinary-thick (400 m) section of the Neogene-Quaternary deposits is for the first time exposed by well No. 1 in the central Uimon Basin. The Miocene-Pliocene lacustrine Tueryk Formation is recognized at the base of the continuous section, verified by new paleontological data (ostracods, spores, and pollen). As assumed, overlaying deposits are represented by the Lower Pleistocene lacustrine-alluvial Beken Formation, Middle Pleistocene alluvial-proluvial Bashkaus Formation, undifferentiated Middle Pleistocene glacial, fluvioglacial, and alluvial deposits, and Upper Pleistocene lacustrine-glacial deposits. The data obtained from the core of well No. 1 undisputably demonstrate that the Uimon Basin had been developed prior the beginning of the Miocene Epoch, when it was characterized by accumulation of the lacustrine Tueryk Formation, incompletely exposed within the studied section. The presence of thick unexposed lower-Ohm interval of sedimentary filling of the basin suggests that the Uimon Basin was developed as early as the Paleogene. Therefore, the tectonic evolution and sedimentation history of the basin are assumed to have features similar to those of the Chuya and Kurai Basins of Gorny Altai. (C) 2017, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

В настоящее время нижняя граница четвертичной системы, согласно решениям Международной комиссии по стратиграфии, принятым на 33-й сессии Международного геологического конгресса, перенесена с уровня 1,8 до 2,588 (≈2,6) млн лет [6]. Удревнение нижней границы привело к включению в состав четвертичной системы верхнего яруса неогена (гелазия). Споры о нижней границе четвертичной системы велись много лет. До 1961 г. эта граница проводилась на уровне 0,7 млн лет. Отложения относились к палеомагнитной зоне Брюнес. На 18-й сессии Международного геологического конгресса и на VI конгрессе ИНКВА в 1961 г. нижняя граница четвертичной системы была понижена, ее рекомендовано было проводить по подошве морских слоев калабрия на уровне 1,8 млн лет. На стратиграфическом совещании в ГИН АН СССР по предложению К. В. Никифоровой нижнюю границу четвертичной системы в России также было предложено перенести на уровень 1,8 млн лет [12], подразделив четвертичный период в ОСШ России на эоплейстоцен и плейстоцен. В связи с понижением нижней границы четвертичной системы и включением в ее состав гелазского яруса остро дискутируется вопрос пересмотра структуры ОСШ России. Б. А. Борисов [1] и В. К. Шкатова [20] предложили рассматривать гелазские отложения в составе эоплейстоцена ОСШ. Предложен и другой, более удобный на наш взгляд, вариант [13], который предусматривает введение нового подразделения нижнего плейстоцена – «палеоплейстоцен». В результате плейстоцен будет состоять из трех разделов: палеоплейстоцена в объеме гелазия МСШ, эоплейстоцена (калабрий МСШ) и неоплейстоцена (ионий и тарантий МСШ). Ярусы пока приняты условно [13]. В связи с понижением нижней границы четвертичной системы в Западной Сибири в нее переведен ряд свит и толщ, входивших в состав верхней части кулундинского горизонта неогена [18]. В схеме нового поколения, по-видимому, должно измениться и положение кочковского горизонта эоплейстоцена [16], возраст и объем которого мы предлагаем здесь рассмотреть. УДК 551.791.03(571.1)

The study presents a summary of the latest data on ostracod microfaunas from Middle–Upper Holocene lacustrine deposits of southern West Siberia collected from lakes Malye Chany, Bol’shaya Lozhka, Beloe, and paleolake Chicha. A total of 28 ostracod species were identified. The identified ostracod assemblages reveal local variations in the lake ecosystems as well as general trends, which can be correlated with both regional and global climate changes. A cooling episode during the second half of the Subboreal is marked by the transition from a warm-water mesohaline assemblage to cold-water candonid ostracods at ca. 3.4 cal ka BP. The widespread occurrence of mesopolythermophilic ostracod species at 1.9–0.6 cal ka BP indicates the end of cooling and lowering of lake-water level. From 0.6 cal ka BP to present, the ostracod assemblages area characterized by the high specific diversity, which is probably an indication of the increased variability of aquatic ecosystems due to fluctuations in salinity and water levels of the lakes. Climate changes identified by ostracod assemblages are consistent with the climatic trend constrained by early palynological studies.