Palaeoclimate characteristics in interior Siberia of MIS 6–2: first insights from the Batagay permafrost mega-thaw slump in the Yana Highlands

Syngenetic permafrost deposits formed extensively on and around the arising Beringian subcontinent during the Late Pleistocene sea level lowstands. Syngenetic deposition implies that all material, both mineral and organic, freezes parallel to sedimentation and remains frozen until degradation of the permafrost. Permafrost is therefore a unique archive of Late Pleistocene palaeoclimate. Most studied permafrost outcrops are situated in the coastal lowlands of northeastern Siberia; inland sections are, however, scarcely available. Here, we describe the stratigraphical, cryolithological, and geochronological characteristics of a permafrost sequence near Batagay in the Siberian Yana Highlands, the interior of the Sakha Republic (Yakutia), Russia, with focus on the Late Pleistocene Yedoma ice complex (YIC). The recently formed Batagay mega-thaw slump exposes permafrost deposits to a depth of up to 80 m and gives insight into a climate record close to Verkhoyansk, which has the most severe continental climate in the Northern Hemi- sphere. Geochronological dating (optically stimulated luminescence, OSL, and 14C ages) and stratigraphic implications delivered a temporal frame from the Middle Pleistocene to the Holocene for our sedimentological interpretations and also revealed interruptions in the deposition. The sequence of lithological units indicates a succession of several distinct climate phases: a Middle Pleistocene ice complex indicates cold stage climate. Then, ice wedge growth stopped due to highly increased sedimentation rates and eventually a rise in temperature. Full interglacial climate conditions existed during accumulation of an organic-rich layer – plant macrofossils reflected open forest vegetation existing under dry conditions during Marine Isotope Stage (MIS) 5e. The Late Pleistocene YIC (MIS 4–MIS 2) suggests severe cold-stage climate conditions. No alas deposits, potentially indicating thermokarst processes, were detected at the site. A detailed comparison of the permafrost deposits exposed in the Batagay thaw slump with well-studied permafrost sequences,both coastal and inland, is made to highlight common features and differences in their formation processes and palaeo-climatic histories. Fluvial and lacustrine influence is tem-orarily common in the majority of permafrost exposures, but has to be excluded for the Batagay sequence. We interpret the characteristics of permafrost deposits at this location as a result of various climatically induced processes that are partly seasonally controlled. Nival deposition might have been dominant during winter time, whereas proluvial and aeolian deposition could have prevailed during the snowmelt period and the dry summer season

Permafrost and man

Permafrost, a thermal condition of the ground, has long been an understated phenomenon because it is not necessarily detectable by the human eye and because it is found in areas that had little economic relevance for mankind. Permafrost-man interactions are however many and manifold. Rising air temperatures in the Arctic, Antarctic and the high mountain regions and consequently rising permafrost temperatures have has resulted in great threats on infrastructure of the higher latitudes northern and mountain, even though man had learnt to build on permafrost since thousands of years in some cases. Accelerating rock glaciers, greater risk of natural hazard in mountain regions, stronger coastal erosion and the danger of gas hydrates thawing are all anthropogenic impacts to a certain extent. Mankind has however also learnt to use the permafrost regions and sought to exploit it early on for its freezing properties in summer to store goods, or recently on a larger scale to protect seeds, to store carbon dioxide or even to extract information from permafrost bacteria in genetic research. The growingåå number of economic activities in the Arctic, the Antarctic and mountain regions will create considerable challenges for the permafrost environment and prompts the need for comprehensive monitoring strategies of permafrost

Modern and fossil diatom assemblages from Bol’shoy Lyakhovsky Island (New Siberian Archipelago, Arctic Siberia)

© 2017, Pleiades Publishing, Ltd. This article discusses the results of a taxonomic and ecological investigation of diatoms from polygonal ponds and Quaternary permafrost deposits of Bol’shoy Lyakhovsky Island (New Siberian Archipelago) and the reconstruction of climatic changes on the Island during late Pleistocene/Holocene transition using fossil diatom assemblages from the permafrost deposits. The taxonomic list of diatoms includes 159 diatom species. The main ecological factors that determine the distribution of diatoms in the investigated data set are mean July air temperature, рН, electrical conductivity, water depth, and concentrations of Si 4+ and Al 3+ . An increase in water depth and stable lacustrine conditions in the Lateglacial–Holocene in the ancient thermokarst lake relate to Lateglacial warming before 11860 ± 160 years BP and during the early Holocene between 11210 ± 160 and 7095 ± 60 years BP

Diatoms of modern bottom sediments in Siberian arctic

The investigation of the species composition and ecology of diatoms of modern bottom sediments in water bodies of arctic polygonal tundra in three subregions of North Yakutiya has been carried out. As a result, 161 taxons of diatoms were determined; the determinant role of the depth, conductivity, pH of the water, and geographic latitude in their distribution was confirmed, and two complexes of species with respect to the leading abiotic factors were distinguished. The diatoms of the first complex prefer shallow water bodies of high latitudes with neutral and slightly alkaline water and relatively high conductivity. The second complex is confined to the water bodies of lower latitudes with small conductivity, as well as neutral and slightly acidic water. © 2012 Pleiades Publishing, Ltd

Ground-ice stable isotopes and cryostratigraphy reflect late Quaternary palaeoclimate in the Northeast Siberian Arctic (Oyogos Yar coast, Dmitry Laptev Strait)

To reconstruct palaeoclimate and palaeoenvironmental conditions in the northeast Siberian Arctic, we studied late Quaternary permafrost at the Oyogos Yar coast (Dmitry Laptev Strait). New infrared-stimulated luminescence ages for distinctive floodplain deposits of the Kuchchugui Suite (112.5 ± 9.6 kyr) and thermokarst-lake deposits of the Krest Yuryakh Suite (102.4 ± 9.7 kyr), respectively, provide new substantial geochronological data and shed light on the landscape history of the Dmitry Laptev Strait region during Marine Isotope Stage (MIS) 5. Ground-ice stable-isotope data are presented together with cryolithological information for eight cryostratigraphic units and are complemented by data from nearby Bol'shoy Lyakhovsky Island. Our combined record of ice-wedge stable isotopes as a proxy for past winter climate conditions covers about 200 000 years and is supplemented by stable isotopes of pore and segregated ice which reflect annual climate conditions overprinted by freezing processes. Our ice-wedge stable-isotope data indicate substantial variations in northeast Siberian Arctic winter climate conditions during the late Quaternary, in particular between glacial and interglacial times but also over the last millennia to centuries. Stable isotope values of ice complex ice wedges indicate cold to very cold winter temperatures about 200 kyr ago (MIS7), very cold winter conditions about 100 kyr ago (MIS5), very cold to moderate winter conditions between about 60 and 30 kyr ago, and extremely cold winter temperatures during the Last Glacial Maximum (MIS2). Much warmer winter conditions are reflected by extensive thermokarst development during MIS5c and by Holocene ice-wedge stable isotopes. Modern ice-wedge stable isotopes are most enriched and testify to the recent winter warming in the Arctic. Hence, ice-wedge-based reconstructions of changes in winter climate conditions add substantial information to those derived from paleoecological proxies stored in permafrost and allow a distinction between seasonal trends of past climate dynamics. Future progress in ice-wedge dating and an improved temporal resolution of ice-wedge-derived climate information may help to fully explore the palaeoclimatic potential of ice wedges

Permafrost in arctic and subarctic lowlands

In recent decades permafrost landscapes in the arctic and subarctic lowlands have experienced warming resulting in a clear rising trend of permafrost temperatures despite some inter-annual variability and occasional cooling or stabilization. A widespread general deepening of the active layer, on the other hand, has not been observed. Changes in the carbon cycle of permafrost ecosystems also remain inconclusive due to a limited number of studies and their usually much localized focus. During the Quaternary environmental history of the Arctic, the non-glaciated Siberian lowlands have repeatedly experienced times of permafrost formation and permafrost degradation. Thus, the climate-change related long-term processes of permafrost dynamics can be reconstructed using environmental indicators from permafrost archives. Additionally, the amount of fossil organic material stored in the permafrost documents the permafrost's relevance for the global carbon cycle. In order to determine the current state and extent of permafrost ecosystems with regard to their thermal, hydrological, geomorphological, and carbon gas emission characteristics, a comprehensive standardized monitoring network combining remote sensing, modelling, long-term observations, and detailed process studies is urgently needed. Only if the current state of permafrost is well known, changes can be detected and future trends and developments can be predicted. That prediction in turn requires a thorough understanding of the paleoenvironmental history of permafrost landscapes

Heterogeneity of Yedoma Ice Complex deposits due to regional genesis processes

Yedoma Ice Complex is a type of permafrost characterized by high ice content and carbon content of approx. 2 wt%. The high ice content makes it very vulnerable to thawing in terms of global warming. Previously stored organic material becomes available for microbial decomposition, releasing carbon into the atmosphere. But Yedoma deposits might be more heterogenous than previously thought. This is indicated by findings from the Yukechi Alas landscape in Central Yakutia where Yedoma deposits with a lack of carbon for several meters are found. Analysis reveals shifts in regional sedimentary processes as a plausible solution to the found heterogenity, making it important to further investigate the composition of Yedoma Ice Complex deposits throughout the arctic. Such heterogenity may change the proposed amount of carbon stored in those deposits but may as well have effects on thaw behaviour and vulnerability to climate warming. Therefore, more information is needed on the scope of such regional influences in order to increase knowledge about the effects of thawing Yedoma on climate change

Testate amoebae in Late Quaternary sediments of the Cape Mamontov Klyk (Yakutia)

The results of the analysis of Rhizopoda from permafrost sediments of the cryolithozone of northeastern Siberia are presented. Testate amoeba communities (Rhizopoda: Testaceafilosea, Testacealobosea) of the late Pleistocene and Holocene and modern habitats of the Cape Mamontov Klyk (the Laptev Sea coast in the vicinity of the Lena River estuary) have been researched. The paleocommunity structure was examined; assessment of rhizopod diversity in sediments of different (fluvial, alluvial, ice complex, alas, and alluvial-dealluvial) geneses was conducted. © 2009 Pleiades Publishing, Inc