Northeast Siberia Research Articles

The middle–late Tournaisian crisis in conodont diversity: a comparison between Northeast Laurussia and Northeast Siberia

The middle–late Tournaisian (Hastarian–Ivorian) transition is marked by isotopic and sedimentological evidence of climatic cooling and glaciations accompanied by a sea level fall and changes in global ocean circulation. At this time, the extinction among conodonts was followed by its gradual recovery in the late Tournaisian–early Viséan. Siphonodellids, representing an important part of conodont assemblages in the early–middle Tournaisian, became extinct. This study aims to compare conodont diversity dynamics in Northeast Laurussia and Northeast Siberia. The materials used range in paleolatitudinal gradients from 20°N (the north of the Urals and Pechora Craton) up to 45°N (Northeast Siberia), and in paleoclimatic gradient from an equatorial to a warm subtropical climate. The middle and late Tournaisian conodont associations of these regions demonstrate a high similarity in taxonomic composition and diversity dynamics, which may suggest that the glaciation and the following decrease in temperature probably was not the direct cause of conodont extinction; instead, the changes in the food web implied by the carbon isotope compositions of conodont elements and host carbonates could have been the main driver of the crisis in conodont diversity

Mining Industry of the Republic of Sakha (Yakutia) and Problems of Environmental and Social Security of Indigenous Peoples

The Republic of Sakha (Yakutia; RS(Y)) is located in the northeast of Siberia (Russia) in the basins of the Lena, Yana, and Indigirka rivers, in the lower reaches of the Kolyma River. Yakutia is an industrial–agrarian republic with a developed mining, fuel, and energy industry. Indigenous peoples live mainly in the Arctic regions, where the large-scale development of mineral resources is planned, and South Yakutia, where the mining industry is well developed. The aim of this study is the development of methodological approaches to assessing the impact of the mining industry on the natural environment and the social sphere in the places of residence and traditional economic activities of the indigenous peoples of the North. We used the results of research work (R&D), materials of expeditionary work, and regulatory documents of the Republic of Sakha (Yakutia) and the Russian Federation (RF). The state of the environment (ES) was assessed on the basis of the analysis of indicators for three areas: (a) anthropogenic load, (b) environmental and social consequences, and (c) resistance of natural complexes to technogenic impacts. In total, 22 indicators were used for the 3 areas, for example, population density, person/km2; the volume of extraction of rock mass, million m3; and emissions, t/year. To bring dissimilar indicators into comparable ones, we used a methodological approach with the use of the social risk index (SRI). In Arctic regions (mainly agricultural), the ES is in a favorable and relatively favorable state: SRI 0.61–0.70; in the central regions (mainly agricultural), it is satisfactory and relatively satisfactory: SRI 0.71–1.0; in the southern and western regions with a developed mining industry, it is relatively tense and tense: SRI 1.01–3.0. An extremely tense state of environmental conditions has developed in the city of Yakutsk: SRI ≥ 3. Generally, the deterioration of the environmental situation and vital activity of the indigenous peoples in investigated Arctic region correlated with the impact of the mining industry.

Leather as a “Marginal” Product of Hunting Sea Animals in the North-East of Siberia (19th — Early 20th Century)

Leather as a “Marginal” Product of Hunting Sea Animals in the North-East of Siberia (19th — Early 20th Century)

Effects of Reversal of Water Flow in an Arctic Floodplain River on Fluvial Emissions of CO2 and CH4

AbstractWhen organic matter from thawed permafrost is released, the sources and sinks of greenhouse gases (GHGs), like carbon dioxide (CO2) and methane (CH4) in Arctic rivers will be influenced in the future. However, the temporal variation, environmental controls, and magnitude of the Arctic riverine GHGs are largely unknown. We measured in situ high temporal resolution concentrations of CO2, CH4, and oxygen (O2) in the Ambolikha River in northeast Siberia between late June and early August 2019. During this period, the largely supersaturated riverine CO2 and CH4 concentrations decreased steadily by 90% and 78%, respectively, while the O2 concentrations increased by 22% and were driven by the decreasing water temperature. Estimated gas fluxes indicate that during late June 2019, significant emissions of CO2 and CH4 were sustained, possibly by external terrestrial sources during flooding, or due to lateral exchange with gas‐rich downstream‐flowing water. In July and early August, the river reversed its flow constantly and limited the water exchange at the site. The composition of dissolved organic matter and microbial communities analyzed in discrete samples also revealed a temporal shift. Furthermore, the cumulative total riverine CO2 emissions (36.8 gC‐CO2 m−2) were nearly five times lower than the CO2 uptake at the adjacent floodplain. Emissions of riverine CH4 (0.21 gC‐CH4 m−2) were 16 times lower than the floodplain CH4 emissions. Our study revealed that the hydraulic connectivity with the land in the late freshet, and reversing flow directions in Arctic streams in summer, regulate riverine carbon replenishment and emissions.

Исторический портрет якутского купца 1-й гильдии Г.В. Никифорова

The article explores the economic, social and charitable activities of Gavrila Nikiforov, a Yakut merchant of the 1st guild. The aim of the publication is to recreate Nikiforov's historical portrait. Achieving this aim involves a wide use of archival sources, previously unpublished and not introduced into scholarly discourse. The topic has not been sufficiently studied in modern historiography of Siberia; it has scientific relevance and significance. The study of the key issue of the publication is based on the methodology of modernization and chronological, systemic, biographical methods. The author determined Nikiforov's origin, place of birth and initial sources of capital accumulation. The article states that Nikiforov established several enterprises with the aim of organizing fur trade in the northern districts of Yakutsk Oblast in 1900-1910. In 1906 Nikiforov's stores were opened in Verkhoyansk, Ko-lymsk, Bulun, Abye, and Kyusyur. In 1914 the merchant became a contributor to the Northern Commercial and Industrial Partnership, bought a trading business of fur traders and became the owner of one of the largest companies in North-East Siberia with a turnover of 1 million rubles a year. In 1914-1919, Nikiforov's annual turnover in fur trade exceeded 1 million rubles. In Yakutsk, Nikiforov conducted wholesale and retail trade in fur, groceries and consumer goods from stores. Nikiforov's supplies of furs to European and North American markets in 1914-1917 amounted to 800 thousand rubles a year. Nikiforov's public education activity was expressed in the construction and maintenance of schools for children, a museum, a library, and financial assistance to residents in paying taxes. During the First World War, Nikiforov was engaged in the procurement and dispatch of warm fur products to the front. Nikiforov enjoyed authority among the local population, was repeatedly elected councilor of the Yakutsk City Council, and was a member of charitable organizations. The merchant took part in meetings under Yakut Governor Ivan Kraft and decided on important strategic issues. In 1918-1919, Nikiforov organized the supply of needy population of Yakutsk Oblast with consumer goods and food products for 400 thousand rubles. For his services, he had state awards. He was an honorary “foreigner” of East-Kangalassky ulus of Yakutsk Oblast. The article defines the personal and business qualities of the Yakut merchant. The main conclusion of the article is that the reconstruction of Nikiforov's historical portrait allowed expanding the previously existing ideas about his contribution to the socioeconomic development of Yakutsk Oblast during the period of modernization of the Russian economy.

Finno-Ugric words in the Russian dialects of Yakutia

This article analyzes the lexical Finno-Ugric borrowings that appeared in the speech of the Slavs and the aboriginal population of Yakutia with the arrival of the Russians to the northeast Siberia in the 17th century. More than three centuries ago, the Russians, who came from the northern provinces of Russia, introduced the essential vocabulary necessary for the daily life of the people of that time into the active vocabulary of the northern region’s population. Most of the words from the Finno-Ugric languages denoted new concepts and did not have synonyms in Russian, for example, viska, edoma, laida, etc. This research investigates and illustrates the most significant thematic groups of the borrowed words, gives lexical-semantic characteristics of the analyzed notions, and determines the basic word-building patterns. This article presents the results of a linguistic experiment on the interpretation of words, which was conducted in 2021 among the students of Ammosov North-Eastern Federal University to determine the relevance of the Finno-Ugric layer of vocabulary in the modern communicative situation of the Sakha Republic (Yakutia). The authors of the article conclude that the studied lexical borrowings, which became widespread on the territory of the republic several centuries ago, underwent some changes, became the basis for the formation of new words, became part of not only the modern Russian literary language, but also other languages of the republic, where they are part of the active vocabulary.

Ethnomusical Traditions of the Russian Old-Timers Folklore of the North-East Siberia as the Research Object

Ethnomusical Traditions of the Russian Old-Timers Folklore of the North-East Siberia as the Research Object

Adaptive Changes in Fatty Acid Desaturation Genes in Indigenous Populations of Northeast Siberia

Adaptive Changes in Fatty Acid Desaturation Genes in Indigenous Populations of Northeast Siberia

Monitoring the Spring Flood in Lena Delta with Hydrodynamic Modeling Based on SAR Satellite Products

Due to the remote location and the extreme climate, monitoring stations in Arctic rivers such as Lena in Siberia have been decreasing through time. Every year, after a long harsh winter, the accumulated snow on the Lena watershed melts, leading to the major annual spring flood event causing heavy transport of sediments, organic carbon, and trace metals, both into as well as within the delta. This study aims to analyze the hydrodynamic processes of the spring flood taking place every year in the Lena Delta. Thus, a combination of remote sensing techniques and hydrodynamic modeling methodologies is used to overcome limitations caused by missing ground-truth data. As a test site for this feasibility study, the outlet of the Lena River to its delta was selected. Lena Delta is an extensive wetland spanning from northeast Siberia into the Arctic Ocean. Spaceborne Synthetic Aperture Radar (SAR) data of the TerraSAR-X/TanDEM-X satellite mission served as input for the hydrodynamic modeling software HEC-RAS. The model resulted in inundation areas, flood depths, and flow velocities. The model accuracy assessed by comparing the multi-temporal modeled inundation areas with the satellite-derived inundation areas ranged between 65 and 95%, with kappa coefficients ranging between 0.78 and 0.97, showing moderate to almost perfect levels of agreement between the two inundation boundaries. Modeling results of high flow discharges show a better agreement with the satellite-derived inundation areas compared to that of lower flow discharges. Overall, the remote-sensing-based hydrodynamic modeling succeeded in indicating the increase and decrease in the inundation areas, flood depths, and flow velocities during the annual flood events.

Types and Micromorphology of Authigenic Carbonates in the Kolyma Yedoma Ice Complex, Northeast Siberia

The study focuses on authigenic carbonates that are widespread in different deposition environments and are a component part of the terrestrial biogeochemical cycle of carbon. Samples from the Kolyma Yedoma Ice Complex that formed during the Sartan Cryochrone (MIS 2), the coldest period of the Late Pleistocene, in the northeastern Siberian lowlands, have been studied utilizing scanning electron microscopy and energy-dispersive spectroscopy with replica technique. The samples bear signatures of irreversible multistage cryogenic changes in structure and composition, with the formation of authigenic minerals. Authigenic carbonates as secondary phases in the Ice Complex deposits are remarkable by local changes in chemical, physical, and other properties, which induce gradual changes in the lattice and conversion of one mineral species to another. As a result, the sediments may contain stable and metastable minerals. Crystalline species like calcite or aragonite precipitate from aqueous solutions and their presence are restricted to free pore space in segregation ice. Metastable phases may be produced as an initial reaction product between the CO2 and the aqueous phase, while mineral surfaces and small pores act as possible nucleation sites. Organic matter is also an important agent in the cryometamorphism of sediments, including precipitation of authigenic phases due to the freezing of colloids and high-molecular compounds.

Age and Palynological Characteristics of Floodplain Deposits of the Kolyma Lowland (North-East Siberia)

River floodplains, reaching several kilometers in width, are one of the main landscape features of the Kolyma Lowland. Their relationship with other forms of relief - yedoma, alasses, and fragments of river terraces - is seen clearly in the Bolshaya Kuropatoch'ya River basin, which is located in the Lowland between 156°30' E and 157°15' E. The first radiocarbon dating of the floodplain deposits of the Kolyma Lowland was undertaken in a study of an outcrop on the left bank of the Bolshaya Kuropatoch'ya River (71°40' N, 156°45' E). Here floodplain sediments, represented by the alternating layers of alluvial silt and peat with a total thickness of 5 m, were exposed along a steep bank of an oxbow lake. The radiocarbon results show that the formation of the modern floodplain of the Bolshaya Kuropatoch'ya River began at the end of the Middle Holocene and continued during the Late Holocene to the present. Since the vegetation cover of arctic and subarctic regions is characterized by low pollen productivity, the spore-pollen spectra of modern and fossil plant communities often include an increased amount of pollen from plant species exotic to the Arctic, brought to the site by long-distance wind transport. For a more reliable interpretation of the spore- pollen spectra of the floodplain sediments, an analysis of the modern vegetation in the Bolshaya Kuropatoch'ya River basin and in a coastal area bordering the East Siberian Sea (about 71°05' N) was carried out, accompanied by an herbarium collection. The radiocarbon-dated palynological data indicate the development of the modern Betula-Salix shrub-herbaceous tundra during the second half of the Holocene. The establishment of this vegetation community reflects the replacement of an earlier Betula forest-tundra, which had prevailed in the northern regions of Western Beringia during the Early Holocene and included Duschekia fruticosa and large shrub species of Salix. Such dramatic changes in the vegetation cover were associated with the rise in sea level about 7.000-6.000 years ago, when seas approached modern levels. This change, in turn, led to a decrease in the contrast of summer and winter temperatures and, thus, to a decrease in the continentality of the climate and a significant reduction in the growing season in the coastal regions of the East Siberian Sea.

Geomorphology and InSAR-Tracked Surface Displacements in an Ice-Rich Yedoma Landscape

Ice-ridge Yedoma terrain is susceptible to vertical surface displacements by thaw and refreeze of ground ice, and geomorphological processes of mass wasting, erosion and sedimentation. Here we explore the relation between a 3 year data set of InSAR measurements of vertical surface displacements during the thaw season, and geomorphological features in an area in the Indigirka Lowlands, Northeast Siberia. The geomorphology is presented in a geomorphological map, based on interpretation of high resolution visible spectrum satellite imagery, field surveys and available data from paleo-environmental research. The main landforms comprise overlapping drained thaw lake basins and lakes, erosion remnants of Late Pleistocene Yedoma deposits, and a floodplain of a high-sinuosity anastomosing river with ancient river terrace remnants. The spatial distribution of drained thaw lake basins and Yedoma erosion remnants in the study area and its surroundings is influenced by neotectonic movements. The 3 years of InSAR measurement include 2 years of high snowfall and extreme river flooding (2017–2018) and 1 year of modest snowfall, early spring and warm summer (2019). The magnitude of surface displacements varies among the years, and show considerable spatial variation. Distinct spatial clusters of displacement trajectories can be discerned, which relate to geomorphological processes and ground ice conditions. Strong subsidence occurred in particular in 2019. In the wet year of 2017, marked heave occurred at Yedoma plateau surfaces, likely by ice accumulation at the top of the permafrost driven by excess precipitation. The spatial variability of surface displacements is high. This is explored by statistical analysis, and is attributed to the interaction of various processes. Next to ground ice volume change, also sedimentation (peat, colluvial deposition) and shrinkage or swelling of soils with changing water content may have contributed. Tussock tundra areas covered by the extreme 2017 and 2018 spring floods show high subsidence rates and an increase of midsummer thaw depths. We hypothesize that increased flood heights along Siberian lowland rivers potentially induce deeper thaw and subsidence on floodplain margins, and also lowers the drainage thresholds of thaw lakes. Both mechanisms tend to increase floodplain area. This may increase CH4 emission from floodplains, but also may enhance carbon storage in floodplain sedimentary environments.

Geochemistry and Weathering Indices of Yedoma and Alas Deposits beneath Thermokarst Lakes in Central Yakutia

Ice- and organic-rich deposits of late Pleistocene age, known as Yedoma Ice Complex (IC), are widespread across large permafrost regions in Northeast Siberia. To reconstruct Yedoma IC formation in Central Yakutia, we analyzed the geochemistry, sedimentology, and stratigraphy of thawed and frozen deposits below two thermokarst lakes in different evolutionary stages (a mature alas lake and a initial Yedoma lake) from the Yukechi site in the Lena-Aldan interfluve. We focused on inorganic geochemical characteristics and mineral weathering in two ∼17 m long sediment cores to trace syngenetic permafrost aggradation and degradation over time. Geochemical properties, element ratios, and specific weathering indices reflect varying sedimentation processes and seasonal thaw depths under variable environmental conditions. Deeper thaw during the interstadial Marine Isotope Stage (MIS) 3 enabled increasing mineral weathering and initial thermokarst processes. Sedimentological proxies reflect high transport energy and short transport paths and mainly terrestrial sediment supply. The Yedoma formation resulted from fluvial, alluvial and aeolian processes. Low mean TOC contents in both cores contrast with Yedoma deposits elsewhere. Likely, this is a result of the very low organic matter content of the source material of the Yukechi Yedoma. Pronounced cryostructures and strongly depleted pore water stable isotopes show a perennially frozen state and preserved organic matter for the lower part of the Yedoma lake core, while changing permafrost conditions, conditions promoting weathering, and strong organic matter decomposition are suggested by our proxies for its middle and upper parts. For the alas lake core, less depleted water stable isotopes reflect the influence of recent precipitation, i.e. the infiltration of rain and lake water into the unfrozen ground. The FENG, MIA(R), and ICV weathering indices have proven to be promising proxies for the identification of conditions that promote mineral weathering to different degrees in the stratigraphy of the thawed and frozen Yedoma deposits, for which we assume a rather homogeneous chemical composition of the parent material. Our study highlights that the understanding of environmental conditions during Yedoma formation and degradation processes by specific geochemical proxies is crucial for assessing the potential decomposition and preservation of the frozen and unfrozen Yedoma inventories.

Thermokarst Lagoons: A Core-Based Assessment of Depositional Characteristics and an Estimate of Carbon Pools on the Bykovsky Peninsula

Permafrost region subsurface organic carbon (OC) pools are a major component of the terrestrial carbon cycle and vulnerable to a warming climate. Thermokarst lagoons are an important transition stage with complex depositional histories during which permafrost and lacustrine carbon pools are transformed along eroding Arctic coasts. The effects of temperature and salinity changes during thermokarst lake to lagoon transitions on thaw history and lagoon deposits are understudied. We analyzed two 30-m-long sediment cores from two thermokarst lagoons on the Bykovsky Peninsula, Northeast Siberia, using sedimentological, geochronological, hydrochemical, and biogeochemical techniques. Using remote sensing we distinguished between a semi-closed and a nearly closed lagoon. We (1) characterized the depositional history, (2) studied the impact of marine inundation on ice-bearing permafrost and taliks, and (3) quantified the OC pools for different stages of thermokarst lagoons. Fluvial and former Yedoma deposits were found at depth between 30 and 8.5 m, while lake and lagoon deposits formed the upper layers. The electrical conductivity of the pore water indicated hypersaline conditions for the semi-closed lagoon (max: 108 mS/cm), while fresh to brackish conditions were observed beneath a 5 m-thick surface saline layer at the nearly closed lagoon. The deposits had a mean OC content of 15 ± 2 kg/m3, with higher values in the semi-closed lagoon. Based on the cores we estimated a total OC pool of 5.7 Mt-C for the first 30 m of sediment below five mapped lagoons on the Bykovsky Peninsula. Our results suggest that paleo river branches shaped the middle Pleistocene landscape followed by late Pleistocene Yedoma permafrost accumulation and early Holocene lake development. Afterward, lake drainage, marine flooding, and bedfast ice formation caused the saline enrichment of pore water, which led to cryotic talik development. We find that the OC-pool of Arctic lagoons may comprise a substantial inventory of partially thawed and partially refrozen OC, which is available for microbial degradation processes at the Arctic terrestrial-marine interface. Climate change in the Arctic leading to sea level rise, permafrost thaw, coastal erosion, and sea ice loss may increase the rate of thermokarst lagoon formation and thus increase the importance of lagoons as biogeochemical processors of former permafrost OC.

Evaluating the Differenced Normalized Burn Ratio for Assessing Fire Severity Using Sentinel-2 Imagery in Northeast Siberian Larch Forests

Fire severity is a key fire regime characteristic with high ecological and carbon cycle relevance. Prior studies on boreal forest fires primarily focused on mapping severity in North American boreal forests. However, the dominant tree species and their impacts on fire regimes are different between North American and Siberian boreal forests. Here, we used Sentinel-2 satellite imagery to test the potential for using the most common spectral index for assessing fire severity, the differenced Normalized Burn Ratio (dNBR), over two fire scars and 37 field plots in Northeast Siberian larch-dominated (Larix cajanderi) forests. These field plots were sampled into two different forest types: (1) dense young stands and (2) open mature stands. For this evaluation, the dNBR was compared to field measurements of the Geometrically structured Composite Burn Index (GeoCBI) and burn depth. We found a linear relationship between dNBR and GeoCBI using data from all forest types (R2 = 0.42, p < 0.001). The dNBR performed better to predict GeoCBI in open mature larch plots (R2 = 0.56, p < 0.001). The GeoCBI provides a holistic field assessment of fire severity yet is dominated by the effect of fire on vegetation. No significant relationships were found between GeoCBI components (overall and substrate stratum) and burn depth within our fires (p > 0.05 in all cases). However, the dNBR showed some potential as a predictor for burn depth, especially in the dense larch forests (R2 = 0.63, p < 0.001). In line with previous studies in boreal North America, the dNBR correlated reasonably well with field data of aboveground fire severity and showed some skills as a predictor of burn depth. More research is needed to refine spaceborne fire severity assessments in the larch forests of Northeast Siberia, including assessments of additional fire scars and integration of dNBR with other geospatial proxies of fire severity.

Regularities of soil temperature changes during the period with snow cover in modern climatic conditions of the Eurasian Subarctic

The influence of snow cover on the dynamics of soil temperature in the modern climatic conditions of the Eurasian Subarctic was investigated through a quantitative assessment of the features of the seasonal and long-term variation of parameters. Seasonal and long-term values of soil temperature for stable snow period decrease from west to east: a decrease of snow thickness and air temperature from west to east of Eurasia leads to a weakening of the heat-insulating properties of the snow cover with a significant decrease in regional air temperatures. With the emergence of a stable snow cover, the soil temperature seasonal and long-term standard deviation sharply decreases compared to the autumn and spring periods. With the appearance of snow cover, the soil temperature standard deviation drops sharply compared to the autumn and spring periods. An exception is the northeast of Siberia: here, a relatively small thickness of snow determines a noticeable dependence of the course of soil temperature on the dynamics of surface air temperature. There are no significant long-term trends in soil temperature due to its low variability during winter period. Analysis of the course of the studied characteristics anomalies showed an insignificant and non-systematic number of their coincidences. Currently, we have not found similar research results for large regions. The revealed patterns can be used in the analysis of the results of monitoring the state of the land surface, in the development of remote sensing algorithms, in the refinement of predictive scenarios of environmental changes.

Этнические особенности расселения якутов в конце ХХ начале ХХI вв.

As you know, the nature and use of space for the resettlement of ethnic groups is important for the study of ethnocultural identity and ethnicity in general. This article is devoted to the influence of the ethnic factor on the features of the settlement of the Yakuts, the indigenous population of the North-East of Siberia of the Russian Federation in extreme, sharply continental climate conditions. The author draws attention to the fact that the natural habitat acquires an ethnic orientation of survival in these conditions. It is now recognized that the indigenous people, like the Yakuts, have acquired high adaptive capabilities in extreme conditions for many generations. The bulk of the Yakuts live in the countryside of central Yakutia, and only a small part of the Yakut ethnic group lives in the northern ulus of the republic. On the territory of central Yakutia there are meadow «islands», the so-called alases (from the Yakut word «alaas») suitable for cattle breeding and horse breeding. Haymaking is the basis of the Yakuts' hay and pasture cattle breeding. Northern cattle breeding, with its haymaking as a traditional way of farming, is known to contribute to the formation of behavioral stereotypes of the Yakuts. Nevertheless, we note that in the modern conditions of globalization, industrial development of the North, value orientations are also changing, many traditional stereotypes of Yakut behavior are being overcome. The article draws attention to the traditional outlook of the Yakuts about the spiritual unity of man and nature, that the sustainable development of the Yakuts is largely related to the problem of the ecology of ethnic culture.

Late Pleistocene paleoecology and phylogeography of woolly rhinoceroses

The woolly rhinoceros (Coelodonta antiquitatis) was a cold-adapted herbivore, widely distributed from western Europe to north-east Siberia during the Late Pleistocene. Previous studies have associated the extinction of the species ∼14,000 calendar years before present to climatic and vegetational changes, suggesting the later survival of populations in north-east Siberia may have related to the later persistence of open vegetation in the region. Here, we analyzed carbon (δ13C) and nitrogen (δ15N) stable isotopes and mitochondrial DNA sequences to elucidate the evolutionary ecology of the species. Our dataset comprised 286 woolly rhinoceros isotopic records, including 192 unpublished records, from across the species range, dating from >58,600 to 12,135 14C years before present (equivalent to 14,040 calendar years ago). Crucially, we present the first 71 isotopic records available to date of the 15,000 years preceding woolly rhinoceros extinction. The data revealed ecological flexibility and geographic variation in woolly rhinoceros stable isotope compositions across time. In north-east Siberia, we detected stability in δ15N through time, which could reflect long-term environmental stability, and may have enabled the later survival of the species in the region. To further investigate the paleoecology of woolly rhinoceroses, we compared their isotopic compositions with other contemporary herbivores. Our findings suggested isotopic similarities between woolly rhinoceros and both musk ox (Ovibos moschatus) and saiga (Saiga tatarica), albeit at varying points in time, and possible niche partitioning between woolly rhinoceros and both horse (Equus spp.) and woolly mammoth (Mammuthus primigenius). To provide phylogeographic context to the isotopic data, we compiled and analyzed the 61 published mitochondrial control region sequences. The genetic data showed a lack of geographic structuring; we found three haplogroups with overlapping distributions, all of which showed a signal of expansion during the Last Glacial Maximum. Furthermore, our genetic findings support the notion that environmental stability in Siberia influenced the paleoecology of woolly rhinoceroses in the region. Our study highlights the utility of combining stable isotopic records with ancient DNA to advance our knowledge of the evolutionary ecology of past populations and extinct species.

Identifying Drivers Behind Spatial Variability of Methane Concentrations in East Siberian Ponds

Waterbody methane emissions per area are negatively correlated with the size of the emitting waterbody. Thus, ponds, defined here as having an area smaller than 8 · 104m2, contribute out of proportion to the aquatic methane budget compared to the total area they cover and compared to other waterbodies. However, methane concentrations in and methane emissions from ponds show more spatial variability than larger waterbodies. We need to better understand this variability to improve upscaling estimates of freshwater methane emissions. In this regard, the Arctic permafrost landscape is an important region, which, besides carbon-rich soils, features a high pond density and is exposed to above-average climatic warming. We studied 41 polygonal-tundra ponds in the Lena River Delta, northeast Siberia. We collected water samples at different locations and depths in each pond and determined methane concentrations using gas chromatography. Additionally, we collected information on the key properties of the ponds to identify drivers of surface water methane concentrations. The ponds can be categorized into three geomorphological types with distinct differences in drivers of methane concentrations: polygonal-center ponds, ice-wedge ponds and larger merged polygonal ponds. All ponds are supersaturated in methane, but ice-wedge ponds exhibit the highest surface water concentrations. We find that ice-wedge ponds feature a strong stratification due to consistently low bottom temperatures. This causes surface concentrations to mainly depend on wind speed and on the amount of methane that has accumulated in the hypolimnion. In polygonal-center ponds, high methane surface concentrations are mostly determined by a small water depth. Apart from the influence of water depth on mixing speed, water depth controls the overgrown fraction, the fraction of the pond covered by vascular plants. The plants provide labile substrate to the methane-producing microbes. This link can also be seen in merged polygonal ponds, which furthermore show the strongest dependence on area as well as an anticorrelation to energy input indicating that stratification influences the surface water methane concentrations in larger ponds. Overall, our findings underpin the strong variability of methane concentrations in ponds. No single driver could explain a significant part of the variability over all pond types suggesting that more complex upscaling methods such as process-based modeling are needed.

Porphyry Cu–Au ± Mo mineralization hosted by potassic igneous rocks: implications from the giant Peschanka porphyry deposit, Baimka Trend (North East Siberia, Russia)

Abstract Porphyry Cu–Au ± Mo mineralization at Peschanka is hosted by monzodiorite and monzonite intrusions with high-K calc-alkaline to shoshonitic compositions and dated at about 144.1 ± 1.5 Ma, using U/Pb zircon ages. The Cretaceous intrusions are emplaced in a melange of Cretaceous island arcs, a tectonic setting comparable with other world-class porphyry Cu–Au deposits, such as Oyu Tolgoi, Mongolia and Pebble, Alaska. Abundant primary magnetite contents of the Peschanka intrusions, as well as numerous gypsum and anhydrite veins, reflect the high oxidation states of their parental magmas. This mineralogical interpretation is confirmed by high whole-rock Fe 2 O 3 /FeO ratios and high V/Sc ratios of the rocks of up to 1.27 and up to 21.9, respectively. The whole-rock Eu/Eu* ratios of the Peschanka intrusions are ≥1 which is also typical for potassic igneous rocks with high oxidation states. Abundant amphibole and biotite phenocrysts of the intrusions as well as their high whole-rock Sr/Y ratios of up to 225 document significantly high H 2 O contents of the high-K magmas. Peschanka contains a resource of >9.5 Mt of copper at an average grade of 0.43 wt% and 16.5 Moz of gold at a high average grade of 0.23 g/t and thus represents one of the largest undeveloped greenfield copper projects worldwide. The vicinity of Peschanka still offers significant brownfield exploration potential. The hypogene vein-related and disseminated Cu–Au ± Mo sulfide mineralization at Peschanka is structurally controlled by significant NE-trending strike-slips that acted as the conduits for the hydrothermal fluids. The central part of the orebody consists of high-grade north–south-trending sheeted quartz–bornite veining with unusually high vein densities. The highest Cu and Au grades are directly correlated with high vein densities. Peschanka is defined by distinct hydrothermal alteration zones including potassic, phyllic, propylitic and argillic assemblages, but a distinct lack of advanced argillic alteration. The mineralization itself is also zoned ranging from a central Mo–Cpy–Bn sulfide assemblage to a peripheral Py–Mt-dominated zone (‘pyrite-shell’). Late-stage polymetallic assemblages overprint and surround the main stockwork zone.