Late Pleistocene Ice Wedges Research Articles

Geochemical Features of Ground Ice from the Faddeevsky Peninsula Eastern Coast (Kotelny Island, East Siberian Arctic) as a Key to Understand Paleoenvironmental Conditions of Its Formation

Understanding paleoenvironmental conditions of the permafrost formation allows us to estimate the permafrost carbon pool and its behavior upon thawing in a changing climate. In order to classify different types of ground ice and to reconstruct paleoenvironments, we examined geochemical data of ice wedges (IWs), tabular ground ice (TGI), and lens ice from the eastern coast of the Faddeevsky Peninsula (East Siberian Arctic). We analyzed isotope and ion composition, molecular composition of the gas phase, bulk biogeochemical parameters and dissolved organic matter (DOM) composition in ground ice samples. IWs formed in the Late Pleistocene under the coldest winter conditions and in the Holocene in proximity to the sea. The Holocene IWs have the highest mean d-excess (11–13‰) and a heavier isotope composition by an average of 6‰ compared with the Late Pleistocene IWs. We observe predominance of sea-salt fractions in ion composition of the Holocene IWs, while the Late Pleistocene IW shows enrichment in non-sea-salt component of SO42− (nssSO42−), which is probably associated with mineral leaching of deposits. Higher dissolved organic carbon (DOC) content in the Late Pleistocene IW (to 17.7 mg/L) may indicate more favorable vegetation conditions or lower degree of organic matter mineralization compared to Holocene IWs and TGI. CH4 concentrations were relatively low with a maximum value of 2.27 μmol/L. DOM composition, supposed to record the paleoenvironment of the freezing process, was for the first time tried as a biomarker for paleoenvironmental reconstructions of ground ice formation. Parallel factor (PARAFAC) analysis of EEM (Excitation-Emission matrix) of fluorescent DOM decomposes four components: P1–P3, which are related to allochthonous humic-like constituents, and P4, which is relevant to autochthonous fraction associated with microbial activity. The distribution of fluorescent DOM tracked the variability in both paleoclimate conditions of the IW formation (discriminating the Holocene and the Late Pleistocene IWs) and types of ground ice (IW and TGI), which demonstrates the potential of the used approach.

Carbon-to-nitrogen ratio in late Pleistocene ice wedges and in modern soils in the Batagay megaslump, north of Yakutia

The content of carbon and nitrogen, as well as the carbon-to-nitrogen ratio in the genetic horizons of the soil cover, yedoma deposits and in organic residues in syngenetic ice wedges (IW) of the upper IW complex of the Batagay megaslump were studied. The studied soils belong to the silty-loam Spodic Cryosol (Dystric,Humic) and post-pyrogenic Spodic Cryosol (Dystric,Humic). To study the carbon and nitrogen content, ice wedges of the first and second tiers of the upper IW complex were tested. The highest values of the C/N ratio were obtained in the upper horizon of the silty- loam Spodic Cryosol (Dystric, Humic) near the Batagay megaslump. The average value of the carbon content in the ice wedges of the Batagay yedoma is of 0.13 mol, the maximum is 0.36 mol, the minimum carbon content is 0.06 mol, the average nitrogen content is of 0.04 mol, maximum 0.12 mol, minimum 0.02 mol. For the entire data array of ice wedges, the value of C/N is of average 3.90, maximum 6.96, minimum 1.05.

Microelements in the Late Pleistocene ice wedges of Seyakha yedoma, east of Yamal Peninsula

The subject of this research is the composition of micro- and macro- rare earth elements in the Late Pleistocene syngenetic ice wedges of the Seyakha yedoma, explored in the outcrop of the Gulf of Ob in the east of Yamal Peninsula (70°9'27.88 "N, 72° 34'8.31" E), north of the Western Siberia. The All-Russian Scientific-research Institution of Mineral Resources after named N.M. Fedorovsky examined the composition of chemical elements in the ice wedges using the methods of atomic-emission spectrometry and mass spectrometry with inductively linked plasma (spectrometers Elan-6100, Optima-4300DV, Perkin-Elmer, Polyvac E-1000, Rank Hilger). The following conclusions were made: 1) Ice wedges of the Seyakha yedoma are rich in macro - and microelements was recorded, which exceeds such in ice wedges of Yakutia by 8-10 times. The high composition of microelements indicates the role of aerosol and soil particles in the formation of chemical composition of ice. The differences between the ice of Yamal and Northeastern Yakutia also testify that the chemical composition reflects the involvement of marine aerosols in ice formation. 2) Rare-earth elements accumulate in the ice of Seyakha yedoma. The composition of all rare-earth elements exceeds the Clarke number in river waters by 69 (Tm ) – 382 (Y) times. 3) Variability of microelement composition within the ice wedge is insignificant, which implies that the water of the polluted with dust and aerosols spring-summer snow is filtered through the entire snow layer and is partially cleaned prior to getting into the ice-break in the ground under the snow.

Geochemical composition of Holocene and Late Pleistocene ice wedges in the yedoma of Stanchikovsky Yar and near the Chersky town, Northern Yakutia

The subject of this research is the Late Pleistocene and Holocene ice wedges exposed near Chersky settlement, lower Kolyma River, and in the yedoma strata of the Stanchikovsky Yar on the Maly Anyuy River. In the yedoma of the Stanchikovsky Yar, multi-tiered syngenetic ice wedges were exposed at different levels – from 10 to 35 m above river level. Ice wedge in the lower tier was sampled in detail. In the yedoma strata near Chersky relatively small fragments of ice wedges up to 1.5 m wide and up to 2 m high were exposed. 1.5-2 km from Chersky within the lacusrtine-paludal depression Holocene ice wedges were exposed. Ice wedges in these three sections was sampled to clarify the geochemical conditions of their formation. It is shown that concentration of Na+, K+, Mg2+, Cl- and SO42- in Holocene and Late Pleistocene ice wedges is very low and mean values do not exceed 5 mg/L. The highest values were obtained for Ca2+, which corresponds to the predominance of this ion in the modern snow of Yakutia and indicates that ice wedges were formed mainly from melted snow. Rather high values of NO3-, reaching 14-27 mg/L, are quite likely due to the swampy environment within polygonal landscapes, where organic matter of both plant and animal origin is decomposed. For comparison, in the water of the Kolyma and Maly Anyu rivers, concentration of nitrates is quite low and does not exceed 0.3 mg/L.

Major and trace elements, δ13C, and polycyclic aromatic hydrocarbons in the Late Pleistocene ice wedges: A case-study of Batagay yedoma, Central Yakutia

We studied the ionic composition of ice, the content of suspended and dissolved trace- and major elements in ice, values of δ13С, and the composition of PAHs of inclusions in the Late Pleistocene syngenetic ice wedges of the Batagay yedoma. For the first time, the complex geochemical study of Batagay megaslump was carried out. The ice of the upper and lower complex of different ages was studied. Mineralisation of the Late Pleistocene ice wedges of Batagay yedoma ranges from 66.56 to 424.8 mg L−1, from ultrafresh to desalinated, the ionic composition of the ice is bicarbonate-calcium and corresponds to snow formed under the influence of continental air masses. The proportion of Ca contained in dissolved form is not more than 20–30%; as for the other elements, the proportion of Mg, K, Na, Al, Fe, Mn, Sr, Ba in suspended form is greater than 90%. The content of trace elements in inclusions in ice wedges and soils is equal, which confirms the pedogenic origin of the inclusions in ice. According to our data, values of δ13С in lipids of the pedogenic material in ice decrease with depth. The lowest values (values of δ13С less than −30‰) were observed in the ice wedge of the upper complex at a depth of 7.4–8.6 m. The increase of δ13C values of lipids from pedogenic material in ice wedges with depth is due to the landscape change from grassland ecosystems to forest ecosystems, and may also be influenced by the increased frequency of fires that occurred during the transition to forest ecosystems and the disappearance of large herbivores.

High-Resolution Oxygen Isotope Diagram of Late Pleistocene Ice Wedges of Seyakha Yedoma, Eastern Yamal Peninsula

The main objective of this work is to study the oxygen isotope composition of late Pleistocene syngenetic ice wedges and to obtain a high-resolution isotope diagram from a carefully sampled outcrop of Seyaha yedoma within of the third lagoon-marine terrace near the Seyaha (Zelyonaya - Green) river mouth, on the bank of the Ob Bay. According to 3 new radiocarbon ages: from 25.2 to 23.3 kyr BP from +2 to +5 m a.s.l., as well as dates: 17.3 kyr from +18.8 m a.s.l. and 11.6 kyr BP from +21.2 m a.s.l., the age of the ice wedge is from 23 to 15 to 18 kyr BP approximately. Values of δ 18 O in the upper fragment of the ice wedge vary from -25.75 to -3.15‰. Horizontal variations of δ 18 O values at a height of +15.2 m amounted to 1.49‰, from -23.41 to -24.9‰. The ice of the lower fragment of the ice wedge, at +6 m a.s.l., is characterized by a wider range of δ 18 O values than in the upper fragment. The horizontal values of δ 18 O range from -23.41 to -26.63‰. The obtained oxygen isotope diagram in the upper fragment of the ice wedge has resolution of 80-100 years. According to palaeoreconstruction the average January temperature 23-15 (18) kyr BP ranged from -35 to -39 °C.

New oxygen isotope diagrams of late pleistocene and holocene ice wedges of Mamontova Gora and Syrdah Lake, Central Yakutia

The aim of the study was to obtain the data of stable oxygen isotope composition of Late Pleistocene and Holocene ice wedges of Mamontova Gora and Syrdakh exposures and their chronology, and reconstruction of winter air temperature during the time of ice wedge formation. Direct dating of organic microinclusions from the ice wedges of Mamontova Gora outcrops allowed to establish that the ice wedges are younger than 20 ka, but older than 10 ka BP. δ18O values of the Late Pleistocene ice wedges of Mamontova Gora vary from -24.7 to -30.9 ‰, δ18O values of the Holocene ice wedges of this exposures range from -23.2 to -25.9 ‰. δ18O values in the Late Pleistocene ice wedges near Syrdakh Lake vary from -29.2 to -32.5 ‰. Reconstructed mean winter air temperature during the most part of the ice wedge growth period in Mamontova Gora site within Late Pleistocene varied from -28 to - 31°C, mean January temperature reached -42, -46°C, for the Syrdakh Lake site Late Pleistocene winter conditions were more severe: mean winter air temperature varied from -30 to -32°C, mean January air temperature reached -44, -48°C. Holocene mean winter air temperature were higher and varied from -24 to - 28°C, mean January temperature varied from -36 to -42°C.

New Oxygen Isotope Diagrams of Late Pleistocene and Holocene Ice Wedges in Mamontova Gora and Syrdakh Lake, Central Yakutia

The aim of the study was to obtain the data of stable oxygen isotope composition of Late Pleistocene and Holocene ice wedges of Mamontova Gora and Syrdakh exposures and their chronology, and reconstruction of winter air temperature during the time of ice wedge formation. Direct dating of organic microinclusions from the ice wedges of Mamontova Gora outcrops allowed to establish that the ice wedges are younger than 20 ka, but older than 10 ka BP. δ 18 O values of the Late Pleistocene ice wedges of Mamontova Gora vary from -24.7 to -30.9 ‰, δ 18 O values of the Holocene ice wedges of this exposures range from -23.2 to -25.9 ‰. δ 18 O values in the Late Pleistocene ice wedges near Syrdakh Lake vary from -29.2 to -32.5 ‰. Reconstructed mean winter air temperature during the most part of the ice wedge growth period in Mamontova Gora site within Late Pleistocene varied from -28 to - 31°C, mean January temperature reached -42, -46°C, for the Syrdakh Lake site Late Pleistocene winter conditions were more severe: mean winter air temperature varied from -30 to -32°C, mean January air temperature reached -44, -48°C. Holocene mean winter air temperature were higher and varied from -24 to - 28°C, mean January temperature varied from -36 to -42°C.

The Oxygen Isotope Composition of Late Pleistocene and Holocene Ice Wedges of Kotelny Island

The aim of the work was to perform paleotemperature reconstructions for the Late Pleistocene and Holocene of Kotelny Island according to oxygen isotope analysis of syngenetic ice wedges. Variations of δ18O in the Late Pleistocene ice wedges formed on Kotelny Island are significant, exceeding 8‰ (from –30‰ to –22.9‰), while they are insignificant at –1.5‰ (from –23.1‰ to –21.6‰) for those in the Holocene. Reconstructions showed that the mean January temperature in the Late Pleistocene changed over 8 to 13°C. The mean annual temperature of frozen soils was about –19 or –20°C in the Late Pleistocene, and about –13 to –15°C in the Holocene, while the current temperature is about –14°C.

AMS14C Dating of Pollen Concentrate from Late Pleistocene ICE Wedges From the Bison and Seyaha Sites in Siberia

Accelerator mass spectrometry (AMS) radiocarbon dates of pollen concentrate were obtained from multistage syngenetic ice wedges of cross-sections from the Late Pleistocene Bison site, located along the Lower Kolyma River (68°34'N, 158°34'E), from ∼43,600 to ∼26,200 BP, and 3 AMS14C dates of pollen concentrate in ice wedges from the Seyaha site cross-section, located on the east coast of the Yamal Peninsula (70°10'N, 72°34'E), from ∼22,400 to ∼25,200 BP. Pollen concentrate samples were prepared using a special pretreatment procedure. Pollen and spores from ice-wedge ice signalize a regional pollen rain. Therefore,14C-dated extracts of pollen and spores from ice-wedge ice enable an adequate reconstruction and chronology of landscape dynamics on a regional scale. The pollen and spores were well preserved despite numerous redepositions in the penecontemporaneous structure in which they were found. Thus, a comparison with dates on other fractions from the same sample is necessary. The youngest date is the most reliable among the intersample AMS14C dates from the ice and permafrost sediments.

Radiocarbon Dating of δ18O-δD Plots in Late Pleistocene Ice-Wedges of the Duvanny Yar (Lower Kolyma River, Northern Yakutia)

The Duvanny Yar cross-section located in the Lower Kolyma River valley of Northern Yakutia (69°N, 158°E, height above the Kolyma River level 55 m), has been studied and dated in detail by radiocarbon. The sequence mainly consists of sandy loam sediments with large syngenetic ice wedges. Their width at the top is 1–3.5 m. Allochthonous organic material occurs in high content, concentrating as 0.5–0.7 m lenses. Shrub fragments, twigs, and mammoth bones are accumulated in peaty layers. Through interpolation based on a series of 14C dates, dating of the host sediments provides an approximate age for the ice wedges. The 14C dates of various types of organic material are sometimes very close, but not all in agreement. Therefore, the dates do not accurately show the age of the δ18O and δD plots. A new approach is developed to a 14C dating strategy of syncryogenic sediments with high admixture of allochthonous organic material. The main purpose of this study is to consider detection of inversions or disturbances in the syngenetic permafrost sediment at the Duvanny Yar cross-section by 14C date series. Direct accelerator mass spectrometry (AMS) dating of the ice confirmed the relatively young age of ice wedges.

First direct dating of Late Pleistocene ice-wedges by AMS

We present the first direct dating by 14C-accelerator mass spectrometry of three Late Pleistocene syngenetic ice-wedges from the Seyaha cross-section. They are representative of permafrost with multistage ice-wedges from the North of Western Siberia. The most important result is the clear vertical age stratification of the ice, i.e. the old ice is located beneath the young. This shows that a timescale can be assigned to these ice-wedges penetrating down into the permafrost. The age of the ice shows a depth of not more than 3–5 m for frost cracking; water penetrated into the ice-wedges at that depth. The lower part of the ice-wedges from the Seyaha cross-section has been dated between 21 000 and 14 000 BP.