Стратиграфия разреза «Марре-Сале» (Западный Ямал) с учётом новых данных радиоуглеродного анализа

Complex structure of the section across the cape Marre-Sale as well as different approaches to its study are the main reasons for continuation of discussion about the age and genesis of deposits and ground ice. New radiocarbon data complement the previously published information about the age characteristics of upper part of the section. It has been found that the upper strata ices having complex shape occur in layers of different age, while they were formed in the Holocene second half.Сложное строение разреза мыса Марре-Сале и разные подходы к его изучению – основные причины продолжения дискуссии о возрасте и генезисе отложений и подземных льдов. Новые радиоуглеродные данные дополняют опубликованные ранее сведения о возрастных характеристиках верхней части разреза. Установлено, что пластовые льды сложной формы в верхней части разреза залегают в разновозрастных толщах, а формировались они во второй половине голоцена

Special Issue: Recent advances (2008 – 2015) in the study of ground ice and cryostratigraphy

Cryostratigraphy involves the description, interpretation and correlation of ground-ice 17 structures (cryostructures) and their relationship to the host deposits. Recent advances in the 18 study of ground ice and cryostratigraphy concern permafrost aggradation and degradation, 19 massive-ice formation and evaluation of ground-ice content. Field studies have increased our 20 knowledge of cryostructures and massive ground ice in epigenetic and syngenetic permafrost. 21 Epigenetic permafrost deposits are relatively ice-poor and composed primarily of pore-filled 22 cryostructures, apart from an ice-enriched upper section and intermediate layer. Syngenetic 23 permafrost deposits are commonly identified from cryostructures indicative of an aggrading 24 permafrost table and are characterized by a high ice content, ice-rich cryofacies, and nested 25 wedge ice. Degradation of ice-rich permafrost can be marked by thaw unconformities, 26 truncated buried ice wedges, ice-wedge pseudomorphs, and organic-rich ‘forest beds’. 27 Studies of massive ground ice have focused on wedge ice, thermokarst-cave ice, intrusive ice, 28 and buried ice. Significant advances have been made in methods for differentiating between 29 tabular massive ice bodies of glacier and intrasedimental origin. Recent studies have utilized 30 palynology, isotope geochemistry and hydrochemistry, in addition to sedimentary and 31 cryostratigraphic analyses. The application of remote sensing techniques and laboratory 32 methods such as CT scanning has improved estimations of the ice content of frozen 33 sediments

Взаимосвязь строения и химического состава прибрежно-морского и озёрного льда в районе мыса Марре-Сале, Западный Ямал

The texture, structure, ionic and trace element composition of samples of fast (coastal-sea) and lake ice collected in 2014 in the area of Cape Marre-Sale (the North-Western Siberia) were analyzed. The following main types of the ice structure were identified in ice sections: firn ice with randomly oriented small crystals; lake large- and small-crystalline bubble ice; layered fast sea ice with small isometric and vertically elongated crystals. The upper part of the lake ice is formed by recrystallized snow containing marine aerosols and lake water. The coefficient of involvement of the main ions from the solution during the ice formation varies for lake ice from 0.02 to 1.51, for sea ice – from 0.10 to 0.23, and for coastal-marine - from 0.03 to 0.04. The difference in the degree of ion involvement into the lake ice is related to the sources of components entering the process of formation of firn and large ice crystals from lake water. Coastal sea ice has high concentrations of trace elements relative to the clarks of sea waters. The income of trace elements into the coastal sea ice is probably determined by continental runoff. It is established that the mineralization of seasonal ice increases with a decrease in the size of crystals. The dependence of the values of the Europium anomaly on the rate of ice formation was revealed. The Europium anomaly in coastal sea ice is inherited from seawater, and the upper part of lake ice is inherited from precipitation.Проанализированы текстура, структура, ионный и микроэлементный состав озёрного и прибрежно-морского льда, отобранного в районе мыса Марре-Сале (Западный Ямал) в 2014 г. Верхняя часть озёрного льда представляет собой фирнизированный снег, имеющий в химическом составе признаки влияния морского аэрозоля. Прибрежно-морской лёд характеризуется слоистой структурой и высокими содержаниями микроэлементов относительно кларков морских вод, источником которых служит континентальный сток. Установлено, что минерализация сезонных льдов увеличивается с уменьшением размеров кристаллов

Текстура и структура подземных льдов позднего голоцена севера Западной Сибири

The Late Holocene ground ices are occurred due to freeze cracking, slope, thermocast, thermoerosion pro‑ cesses. New formation ice within may intervene to the Pleistocene, lower Holocene ground ice and perma‑ frost and can really complicate their structure. Relationship between seasonal and perennial new formation of ice with massive ice and permafrost was studied in cross section of the North Western Siberia. The features of texture and structure of ice formed in the thawing cavities, some cracks were determined. The differences in structure of the late Holocene ground ices and ground ices of the early Holocene and late Pleistocene were defined. The differences in ground ice texture and structure depend to the cavity configuration of the freezing and cracks and freezing temperature conditions. The quantitative parameters of the crystal structure can be used to identify closed‑cavity ice and crack ice in the composition of massive ice and determine mechanisms and conditions of formation before the Holocene ice wedges.В разрезах севера Западной Сибири изучено соотношение новообразований льда с залежеобразую щими льдами и мёрзлыми отложениями. Определены особенности текстуры и структуры льдов, сформированных в полостях протаивания, трещинах отседания и трещинах в тыловой части оползневых блоков мёрзлых пород. Установлены отличия структуры подземных льдов позднего голоцена от подземных льдов раннего голоцена и позднего плейстоцена

Гетерогенное строение полигонально-жильных льдов в торфяниках Пур-Тазовского междуречья

Structure of arctic peatlands with massive ice and structure-forming ice were studied in drained lake («khasyrey») of the Pur-Taz interfluves (the north of West Siberia). The period of accumulation of two-meter thickness of the peat was established to be changed from 8413±90 to 897±90 years BP. Composition of the peat deposits is represented by Betula nana, Sphagnum  sp., Vaccinium oxycoccos, Eriophorum  sp., Equisetum sp. The massive ice is represented by ice wedges with large shoulders and young ice wedges. The central part of the ice wedge is composed by recrystallized crystals of ice veins. Melting zones (elongated crystals of segregated ice and closed-cavity ice) were found in the shoulders of the ice wedge and in the upper part of the young ice wedge. Young ice wedges in the central and lateral parts the main wedge have a similar structure in the cross-section, but they are built by different genetic types of ice: the ice veins or closed-cavity ice with segregated ice. Ice-rich peat contains different types of ice inclusions and subhorizontal ice belts and ice lenses. Ice lenses in the peat can be formed by the segregated ice and/or infiltrated-segregated ice. The hydrochemical composition of the ice wedges, ice lenses, surface water samples and the aqueous extract from peat was analyzed. Hydrochemical analysis did show that polygonal-core ice has basically similar composition with the present-day atmospheric precipitation and surface waters of the polygonal bath; in the area of the shoulder – the composition is intermediate between the ground waters of peat and the central part of the vein. The hydrochemical composition of the ice lenses is similar to the composition of the lake water and peat underlying the active layer. The methane concentrations and its distribution within the ice wedges, peat and lens ice were determined. The closed-cavity ice doesn’t contain methane; the ice wedges with ice veins have minimal methane concentrations; large ice lenses have differentiation of methane concentrations. High concentrations of methane are typical for the frozen peat with inclusions of closed-cavity ice in the uppermost part of permafrost layer; the maximum methane concentration was determined inside the peat with ice lenses. The heterogeneous ices inside the ice wedges, distribution of hydrochemical compounds and methane distribution were conditioned by dynamics of the melting depth during the peatland formation under changing climate of the Holocene in the Arctic.Изучены состав и строение голоценового торфяника возрастом от 8413±90 до 897±90 радиоуглеродных лет. В строении жилы установлены генетически разные типы льда: элементарные жилки, термокарстово-полостной, сегрегационный. Определёны химический состав водно-растворимых соединений, а также концентрация метана во льду и торфе, которая связана с динамикой глубины протаивания в условиях меняющегося климата в голоцене

Строение и формирование ледогрунтовых жил второй озёрно-аллювиальной террасы на севере Гыдана в позднем неоплейстоцене–голоцене

The syngenetic ice and ice-ground composite veins in khasyrey (alas) and interalas plateaus were studied on the second lake-alluvial terrace located in the North of the Gydan Peninsula near the village of Gyda. On the basis of the radiocarbon dating, the time of formation of deposits containing veins from was established – from 16 640 to 854 BP. The peat deposits are mainly represented by the following species: Carex sp., Eriophorum  sp., Betula nana, Equisetum  sp., Calamagrostis  sp., Vaccinium vitis-idaea, Drepanocladus  sp., Empetrum sp., Vaccinium uliginosum, Rubus arcticus, Petasites sp. It is established that the polygonal-veined ice of khasyrey and interalas plateaus, except for vertical-striped «clean» ice, contain areas with vertical wavy streaks of ice-ground. Ice of elementary veins and segregation ice were revealed in the composition of veins according to structural and textural features in polarized light. Elementary ice veins compose «clean» ice sections of veins and segregation ice which are their ice-ground sections. Elementary veins are indicative of the predominance of the process of frost cracking during the formation of polygonal-vein ices. The presence of inclusions of ice-ground in the structure of veins points is evidence of a manifestation of local thermokarst processes under the growth of polygonal-vein ice. Ice-ground veins were formed by repeated thawing of the initial ice veins. The formation of ice-ground veins during syngenetic freezing of sediments of the second lake-alluvial terrace is related to uneven manifestation of thermokarst in different facies situations and and climate changes at the Early Pleistocene and Holocene.Изучены сингенетические ледяные и ледогрунтовые жилы, а также сезонно- и мёрзлые отложения на севере Гыданского полуострова. Включение сегрегационного льда в состав полигонально-жильного проходило в период сингенетического промерзания осадков второй террасы на севере Гыдана в динамичной озёрно-аллювиальной обстановке и связано с неравномерным проявлением термокарста во второй половине сартанского периода и в голоцене

Geological and geomorphological evolution of a sedimentary periglacial landscape in Northeast Siberia during the Late Quaternary

A wide variety of environmental records is necessary for analysing and understanding the complex Late Quaternary dynamics of permafrost-dominated Arctic landscapes. A NE Siberian periglacial key region was studied in detail using sediment records, remote sensing data, and terrain modelling, all incorporated in a geographical information system (GIS). The study area consists of the Bykovsky Peninsula and the adjacent Khorogor Valley in the Kharaulakh Ridge situated a few kilometres southeast of the LenaDelta. In this study a comprehensive cryolithological database containing information from 176 sites was compiled. The information from these sites is based on the review of previously published borehole data, outcrop profiles, surface samples, and our own field data. These archives cover depositional records of three periods: from Pliocene to Early Pleistocene, the Late Pleistocene and the Holocene. The main sediment sequences on the Bykovsky Peninsula consist of up to 50 m thick ice-rich permafrost deposits (Ice Complex) that were accumulated during the Late Pleistocene. They were formed as a result of nival processes around extensive snowfields in the Kharaulakh Ridge, slope processes (in relatively steep areas such as the Khorogor Valley), and alluvial/proluvial sedimentation in a flat accumulation plain dominated by polygonal tundra in the mountain foreland (Bykovsky Peninsula). During the early to middle Holocene warming, a general landscape transformation occurred from an extensive Late Pleistocene accumulation plain to a strongly thermokarst-dominated relief dissected by numerous depressions. Thermokarst subsidence had an enormous influence on the periglacial hydrological patterns, the sediment deposition, and on the composition and distribution of habitats. Climate deterioration, lake drainage, and talik refreezing occurred during the middle to late Holocene. The investigated region was reached by the post-glacial sea level rise during the middle Holocene, triggering thermo-abrasion of ice-rich coasts and the marine inundation of thermokarst depressions

Stratigraphy of the section «Marre-Sale» (West Yamal): analysis with consideration for new data on radiocarbon

Complex structure of the section across the cape Marre-Sale as well as different approaches to its study are the main reasons for continuation of discussion about the age and genesis of deposits and ground ice. New radiocarbon data complement the previously published information about the age characteristics of upper part of the section. It has been found that the upper strata ices having complex shape occur in layers of different age, while they were formed in the Holocene second half

Detailed stratigraphy and dynamics of Central Yamal khasyrey during the late holocene

The relevance of the discussed issue is caused by insufficient knowledge of the stratigraphy and dynamics of peatland of the Western Siberia tundra zone and of the impact of permafrost conditions and climate. The main aim of the study is the detailed study of stratigraphic and reconstruction of the dynamics of plant communities, water regimes and geocryological conditions of Central Yamal khasyrey. The methods used in the study: detailed (1…3,5 cm) study of the macrofossils composition and physic-chemical properties of peat, radiocarbon dating (6 dates) peat deposit; reconstruction of phytoceanoses and water regimes by traditional paleoecological methods, reconstruction of paleogeocryological conditions according to paleophytocoenoses successions and peat secondary diagenesis; comparative analysis of the obtained data with the data of reconstructions of regional climate and functional state of mires to other zones and regions. The results. For the first time the authors have obtained the detailed stratigraphy of peat deposits, data on peat density and its organic substance. By the example of the khasyrey in the Lake Sokhonto area of Central Yamal the authors determined the impact of paleo-cryological conditions on increase of peat decomposition level and density. The y carried out the detailed reconstruction of khasyrey dynamics for the 1350-year period of its formation. Seven large stages and 15 stages with 6 substages of khasyrey formation of interdecadal and century scale were revealed. Water regimes and cryogenic conditions of these stages are in agreement with regional climate reconstructions data and the solar activity periods. The authors differentiated 2 periods in which khasyrey surface was wet: 952…843; 273 cal. yr. BP…2001 yr. The khasyrey surface was drained maximally during 4 periods: 1099…1065 and 1037…984; 719-652; 542…434 cal. yr. BP. The short-term formation of low permafrost mound during periods of 1099…1065; 1008…984 and 719…652 cal. yr. BP is of high probability. Formation of polygonal mire took place during 542…434 cal. yr. BP. Since 434 cal. yr. BP the depth of seasonal thawing increased, and since 330 cal. yr. BP of ice veins started melting, formation of mire with raised-centre polygons, caused by thermokarst and erosion. In 136...91 cal. yr. BP the depth of seasonal thawing decreased. Drainage of a khasyrey surface in a consequence of waters dumping of the khasyrey lake during the wet warm periods took place between 1153 and 1099, 869 and 843 cal. yr. BP; ca. 2003 and 2008 yrs. Thus, climate changes in the Western Siberia tundra were the main cause of pulsating nature of khasyreis in contrast to the more southern areas. Climate influence was direct, through the hydrothermal regime, and indirect, through cryogenic processes in peat deposit and the water table regime of the lake. Optimal conditions for palsa and polygonal mire formation were created with increasing continental climate and summer temperatures during periods of dry cooling