East Siberian Ice Research Articles

Depositional and circulation changes at the Chukchi margin, Arctic Ocean, during the last two glacial cycles

The shallow Chukchi-East Siberian margin of the Arctic Ocean was repeatedly impacted by Pleistocene glaciations and related changes in sea level and circulation. The depositional history across the last two Arctic glacial cycles is investigated in sediment core ARC6-C15 from the foot of the Chukchi Rise, an extension of the Chukchi Sea shelf that was impacted by the East Siberian Ice Sheet (ESIS). Our proxy data indicate a large extent of the ESIS, likely blocking the westward sediment transport from the Laurentide Ice Sheet (LIS) during the penultimate glaciation estimated to have occurred within an age span from Marine Isotope Stage (MIS) 4 to 6. The deglacial environments are characterized by enhanced sediment inputs from the East Siberian and Chukchi shelves, while overlying interstadial/interglacial sediments have a signature of the Chukchi Sea and the Beaufort Gyre. During the last glaciation, the ESIS had a smaller impact on the Chukchi margin, and the deglaciation was dominated by the LIS sediment sources. Glacial discharge from the Mackenzie area is identified in the Bølling/Allerød interval, while later deglacial pulses can be tracked to the Canadian Arctic Archipelago. In addition to glacigenic sediment inputs, both deglacial intervals contain FeMn micronodules, possibly formed under the influence of meltwater pulses during sea level rise. An increase in the chlorite content that likely marks the flooding of the Bering Strait is identified at the start of the Holocene. A pronounced oxygen and carbon isotope excursion in the early Holocene may indicate hydrographic changes in the Arctic Ocean related to the 8.2 ka meltwater discharge event.

Effects of Thawing Conditions in Sample Treatment on the Chemical Properties of East Siberian Ice Wedges

Effects of Thawing Conditions in Sample Treatment on the Chemical Properties of East Siberian Ice Wedges

Late Pleistocene Laurentide-source iceberg outbursts in the western Arctic Ocean

The source, amount, and trajectory of icebergs discharged into the western Arctic Ocean provide essential clues to Arctic ice sheet development and its feedback on Atlantic meridional overturning circulation (AMOC). Nd and Sr isotopes, ice-rafted debris, and mineral components were used to trace the icebergs that were first discharged into the western Arctic Ocean and then exported to the North Atlantic Ocean. The records indicated that the iceberg outburst (large-scale iceberg export via the Fram Strait) since the Late Pleistocene does not entirely depend on the iceberg discharge from the Laurentide ice sheet (LIS), which is mainly the result of multi-source ice interactions over the western Arctic Ocean. In marine isotope stage 5 (MIS5) and the MIS3a (39–29 ka), the LIS did not reach its maximum extent, discharging its most massive icebergs into the western Arctic Ocean. However, most icebergs were trapped in the western Arctic Ocean, instead of being exported to the North Atlantic Ocean. Different scenarios occurred in the MIS4 and MIS2, when the East Siberian ice sheet (ESIS) emerged and icebergs in the western Arctic Ocean began to accumulate robustly. Ice streams from the LIS or Eurasian ice sheet (EAIS) were finally deflected and pushed to the Fram Strait by the ice streams from the ESIS. The ESIS expansion may thus play a more positive role than the LIS-iceberg discharge in triggering Laurentide-source iceberg outbursts in the western Arctic Ocean. Our findings shed new light on the origin of icebergs in the North Atlantic Ocean and mechanisms of AMOC instability.

Heavy mineral assemblages of the De Long Trough and southern Lomonosov Ridge glacigenic deposits: implications for the East Siberian Ice Sheet extent

Abstract. The Arctic's glacial history has classically been interpreted from marine records in terms of the fluctuations of the Eurasian and North American ice sheets. However, the extent and timing of the East Siberian Ice Sheet (ESIS) have remained uncertain. A recently discovered glacially scoured cross-shelf trough extending to the edge of the continental shelf north of the De Long Islands has provided additional evidence that glacial ice existed on parts of the East Siberian Sea (ESS) during previous glacial periods MIS 6 and 4. This study concentrates on defining the heavy mineral signature of glacigenic deposits from the East Siberian continental margin which were collected during the 2014 SWERUS-C3 expedition. The cores studied are 20-GC1 from the East Siberian shelf, 23-GC1 and 24-GC1 from the De Long Trough (DLT), and 29-GC1 from the southern Lomonosov Ridge (LR). Heavy mineral assemblages were used to identify prominent parent rocks in hinterland and other sediment source areas. The parent rock areas include major eastern Siberian geological provinces such as the Omolon massif, the Chukotka fold belt, the Verkhoyansk fold belt, and possibly the Okhotsk–Chukotka volcanic belt. The primary riverine sources for the ESS sediments are the Indigirka and Kolyma rivers, the material of which was glacially eroded and re-deposited in the DLT. The higher abundances of amphiboles in the heavy mineral assemblages may indicate ESS paleovalley of the Indigirka River as a major pathway of sediments, while the Kolyma River paleovalley pathway relates to a higher share of pyroxenes and epidote. The mineralogical signature in the DLT diamicts, consisting predominantly of amphiboles and pyroxenes with a minor content of garnet and epidote, shows clear delivery from the eastern part of the ESIS. Although the physical properties of the DLT glacial diamict closely resemble a pervasive diamict unit recovered from the southern LR, their source material is slightly different. The assemblages with elevated amphibole and garnet content, along with higher titanite and ilmenite content of the southern LR ice-rafted diamict, emphasise the Verkhoyansk fold belt as a possible primary source. The presence of glacial sediments and the recovered glacial–tectonic features on the East Siberian continental shelf and slope, along with the results from this heavy mineral analysis, imply that glacial ice not only grew out of the East Siberian shelf but also from the De Long Islands, and that there was also ice rafting related sediment transportation to the southern LR from westerly sources, such as the Laptev Sea.

Isotopic Fingerprints of Ice‐Rafted Debris Offer New Constraints on Middle to Late Quaternary Arctic Circulation and Glacial History

AbstractFor the first time, ice‐rafted debris provenance related to the Quaternary glacial discharge and circulation was constrained using radiogenic Sr, Nd, and Pb isotopes from a sedimentary record (Core BN05) from the central Arctic Ocean. The record is composed of glacial/interglacial intervals estimated to span ~0.5 Ma (Marine Isotope Stages [MIS] 1–14). Nd versus Sr isotope data show two end member groups, further elaborated using Pb isotopes. Glacial data mostly point at North American sources with unradiogenic εNd and high 87Sr/86Sr values, including detrital carbonate (dolomite) layers originating from Paleozoic rocks eroded by the Laurentide Ice Sheet. The opposite end member group including estimated MIS6 and MIS4 samples indicates the Siberian Large Igneous Province eroded by the Eurasian Ice Sheet as the major source, possibly with additional inputs from the East Siberian Ice Sheet. The limited evidence for Siberian Ice Sheet provenance may result from the predominant distribution of this glaciation on the continental shelf providing weak, fine‐grained sediments. Glacial‐time western Arctic circulation inferred from isotopic data is mostly similar to the modern Beaufort Gyre but was more streamlined toward the Fram Strait during some glacial events. Interglacial/major interstadial, presumably sea ice transported sediments, shows a mixture of North American and Siberian sources, consistent with historically observed variations in the Transpolar Drift versus Beaufort Gyre circulation. Isotope pattern in major interglacials (e.g., MIS5e, MIS11, and MIS 13) resembles the recent trend of increased sediment ice transport from the East Siberian/Chukchi Sea, possibly in relation to the ongoing Arctic warming.

Ice events along the East Siberian continental margin during the last two glaciations: Evidence from clay minerals

A large ice sheet or ice shelf may have developed repeatedly along the East Siberian continental margin since the Middle Pleistocene. In combination with ice-rafted debris, major elements, and foraminifera, clay mineral records from four gravity sediment cores are used to trace ice events along the East Siberian continental margin during the last two glaciations. The clay mineral assemblages show a strong link to the extent of the East Siberian ice sheet (ESIS) rather than the ice shelf or icebergs sourced from the Canadian Arctic. During the last two glaciations, illite-rich sediment from East Siberia was transported mainly toward the deep basin, whereas kaolinite-rich sediment from the Canadian Arctic was mostly blocked from the East Siberian continental margin. We speculate that during marine isotope stage 2 (MIS2), the southern Mendeleev Ridge, Chukchi Basin, and Chukchi Rise may have been covered by an ESIS-extended ice shelf; however, the Chukchi Plateau and Northwind Ridge were dominated by a Laurentide-sourced ice shelf. During MIS4, the ESIS may have undergone a marked expansion, with an extended ice shelf occupying all of the Chukchi Plateau and Northwind Ridge, thereby restricting iceberg discharge from other ice sheets.

Numerical simulations of a kilometre-thick Arctic ice shelf consistent with ice grounding observations

Recently obtained geophysical data show sets of parallel erosional features on the Lomonosov Ridge in the central Arctic Basin, indicative of ice grounding in water depths up to 1280 m. These features have been interpreted as being formed by an ice shelf—either restricted to the Amerasian Basin (the “minimum model”) or extending across the entire Arctic Basin. Here, we use a numerical ice sheet-shelf model to explore how such an ice shelf could form. We rule out the “minimum model” and suggest that grounding on the Lomonosov Ridge requires complete Arctic ice shelf cover; this places a minimum estimate on its volume, which would have exceeded that of the modern Greenland Ice Sheet. Buttressing provided by an Arctic ice shelf would have increased volumes of the peripheral terrestrial ice sheets. An Arctic ice shelf could have formed even in the absence of a hypothesised East Siberian Ice Sheet.

Sedimentary record from the Canada Basin, Arctic Ocean: implications for late to middle Pleistocene glacial history

Abstract. Sediment core ARC4-BN05 collected from the Canada Basin, Arctic Ocean, covers the late to middle Quaternary (Marine Isotope Stage – MIS – 1–15, ca. 0.5–0.6 Ma) as estimated by correlation to earlier proposed Arctic Ocean stratigraphies and AMS14C dating of the youngest sediments. Detailed examination of clay and bulk mineralogy along with grain size, content of Ca and Mn, and planktic foraminiferal numbers in core ARC4–BN05 provides important new information about sedimentary environments and provenance. We use increased contents of coarse debris as an indicator of glacier collapse events at the margins of the western Arctic Ocean, and identify the provenance of these events from mineralogical composition. Notably, peaks of dolomite debris, including large dropstones, track the Laurentide Ice Sheet (LIS) discharge events to the Arctic Ocean. Major LIS inputs occurred during the stratigraphic intervals estimated as MIS 3, intra-MIS 5 and 7 events, MIS 8, and MIS 10. Inputs from the East Siberian Ice Sheet (ESIS) are inferred from peaks of smectite, kaolinite, and chlorite associated with coarse sediment. Major ESIS sedimentary events occurred in the intervals estimated as MIS 4, MIS 6 and MIS 12. Differences in LIS vs. ESIS inputs can be explained by ice-sheet configurations at different sea levels, sediment delivery mechanisms (iceberg rafting, suspension plumes, and debris flows), and surface circulation. A long-term change in the pattern of sediment inputs, with an apparent step change near the estimated MIS 7–8 boundary (ca. 0.25 Ma), presumably indicates an overall glacial expansion at the western Arctic margins, especially in North America.

An East Siberian ice shelf during the Late Pleistocene glaciations: Numerical reconstructions

Abstract A recent data campaign in the East Siberian Sea has revealed evidence of grounded and floating ice dynamics in regions of up to 1000 m water depth, and which are attributed to glaciations older than the Last Glacial Maximum (21 kyrs BP). The main hypothesis based on this evidence is that a small ice cap developed over Beringia and expanded over the East Siberian continental margin during some of the Late Pleistocene glaciations. Other similar evidence of ice dynamics that have been previously collected on the shallow continental shelves of the Arctic Ocean have been attributed to the penultimate glaciation, i.e. Marine Isotopes Stage 6 (≈140 kyrs BP). We use an ice sheet model, forced by two previously simulated MIS 6 glacial maximum climates, to carry out a series of sensitivity experiments testing the impact of dynamics and mass-balance related parameters on the geometry of the East Siberian ice cap and ice shelf. Results show that the ice cap developing over Beringia connects to the Eurasian ice sheet in all simulations and that its volume ranges between 6 and 14 m SLE, depending on the climate forcing. This ice cap generates an ice shelf of dimensions comparable with or larger than the present-day Ross ice shelf in West Antarctica. Although the ice shelf extent strongly depends on the ice flux through the grounding line, it is particularly sensitive to the choice of the calving and basal melting parameters. Finally, inhibiting a merging of the Beringia ice cap with the Eurasian ice sheet affects the expansion of the ice shelf only in the simulations where the ice cap fluxes are not large enough to compensate for the fluxes coming from the Eurasian ice sheet.

Observing Muostakh disappear: permafrost thaw subsidence and erosion of a ground-ice-rich island in response to arctic summer warming and sea ice reduction

Abstract. Observations of coastline retreat using contemporary very high resolution satellite and historical aerial imagery were compared to measurements of open water fraction, summer air temperature, and wind. We analysed seasonal and interannual variations of thawing-induced cliff top retreat (thermo-denudation) and marine abrasion (thermo-abrasion) on Muostakh Island in the southern central Laptev Sea. Geomorphometric analysis revealed that total ground ice content on Muostakh is made up of equal amounts of intrasedimentary and macro ground ice and sums up to 87%, rendering the island particularly susceptible to erosion along the coast, resulting in land loss. Based on topographic reference measurements during field campaigns, we generated digital elevation models using stereophotogrammetry, in order to block-adjust and orthorectify aerial photographs from 1951 and GeoEye, QuickBird, WorldView-1, and WorldView-2 imagery from 2010 to 2013 for change detection. Using sea ice concentration data from the Special Sensor Microwave Imager (SSM/I) and air temperature time series from nearby Tiksi, we calculated the seasonal duration available for thermo-abrasion, expressed as open water days, and for thermo-denudation, based on the number of days with positive mean daily temperatures. Seasonal dynamics of cliff top retreat revealed rapid thermo-denudation rates of −10.2 ± 4.5 m a−1 in mid-summer and thermo-abrasion rates along the coastline of −3.4 ± 2.7 m a−1 on average during the 2010–2013 observation period, currently almost twice as rapid as the mean rate of −1.8 ± 1.3 m a−1 since 1951. Our results showed a close relationship between mean summer air temperature and coastal thermo-erosion rates, in agreement with observations made for various permafrost coastlines different to the East Siberian Ice Complex coasts elsewhere in the Arctic. Seasonality of coastline retreat and interannual variations of environmental factors suggest that an increasing length of thermo-denudation and thermo-abrasion process simultaneity favours greater coastal erosion. Coastal thermo-erosion has reduced the island's area by 0.9 km2 (24%) over the past 62 years but shrank its volume by 28 x 106 m3 (40%), not least because of permafrost thaw subsidence, with the most pronounced with rates of ≥− 11 cm a−1 on yedoma uplands near the island's rapidly eroding northern cape. Recent acceleration in both will halve Muostakh Island's lifetime to less than a century.

Widespread, multi-source glacial erosion on the Chukchi margin, Arctic Ocean

Multibeam bathymetry and sub-bottom profiler data acquired in 2011 from R/V Marcus Langseth in a broad grid over the Chukchi Sea margin reveal multiple glacigenic features on the top and slopes of the outer Chukchi Shelf/Rise and adjacent Borderland. Glacial lineations record a complex pattern of erosion likely formed by both local glaciation and far-traveled ice shelves/streams sourced from the Laurentide, and possibly East Siberian ice sheets. Multiple till units and stacked debris flows indicate recurrent glacial grounding events. Composite till wedges of several hundred meters thick extend the shelf edge by 10–20 km in places. Distribution of ice-marginal features on the Chukchi Rise suggests stepwise deglacial retreat towards the shelf, backing up the broad bathymetric trough at the eastern side of the Rise. Glacigenic features other than extensive iceberg scouring cannot be identified above 350-m depth, and no glacigenic bedforms are present on the current-swept shallow shelf. Despite the resulting uncertainty with the southern extent of the glaciation, the data suggest a widespread grounded-ice presence on the northern Chukchi Shelf, which makes it an important, previously underestimated component of the Arctic paleo-glacial system.

Pleistocene raised marine deposits on Wrangel Island, northeast Siberia and implications for the presence of an East Siberian ice sheet

Two previously undocumented Pleistocene marine transgressions on Wrangel Island, northeastern Siberia, question the presence of an East Siberian or Beringian ice sheet during the last glacial maximum (LGM). The Tundrovayan Transgression (459,000–780,000 yr B.P.) is represented by raised marine deposits and landforms 15–41 m asl located up to 18 km inland. The presence of high sea level 64,000–73,000 yr ago (the Krasny Flagian Transgression) is preserved in deposits and landforms 4–7 m asl in the Krasny Flag valley. These deposits and landforms were mapped, dated, and described using amino acid geochronology, radiocarbon, optically stimulated luminescence, electron spin resonance, oxygen isotopes, micropaleontology, paleomagnetism, and grain sizes. The marine deposits are eustatic and not isostatic in origin. All marine deposits on Wrangel Island predate the LGM, indicating that neither Wrangel Island nor the East Siberian or Chukchi Seas experienced extensive glaciation over the last 64,000 yr.

Climate impacts of an ice sheet in East Siberia during the Last Glacial Maximum

Recent evaluations of geomorphological evidence in East Siberia strongly suggest that no ice sheet existed on the East Siberian Arctic Shelf during the Last Glacial Maximum (LGM), contrary to the hypothesis of some authors. Because most general circulation model (GCM) simulations of the LGM have included such an ice sheet, the impact of an East Siberian ice sheet is crucial for understanding previous model simulations of the LGM. The experiments in this study use the Global Environmental and Ecological Simulation of Interactive Systems (GENESIS) 2.0 GCM and the Equilibrium Vegetation Ecology (EVE) vegetation model to simulate the LGM climate with (previously published simulation) and without (new simulation) an East Siberian ice sheet. Most LGM simulations have shown increased southerly advection into Beringia resulting from the dynamics of the continental ice sheets, which acts to alleviate the hemispheric-glacial cooling in Beringia. The East Siberian ice sheet provides a secondary source of warm-air advection into Beringia. In the simulation with an East Siberian ice sheet a glacial anticyclone develops over the ice sheet during winter, resulting in subsidence of air flowing off the ice sheet, increased southerly advection along the western margin of the ice sheet, and warming to the south of the ice sheet. During summer the ice sheet blocks northerly flow from the arctic, also resulting in warming south of the ice sheet. The primary vegetation difference is in the ratio of tundra to polar desert. The more mild climate with the ice sheet present produces more tundra and less polar desert.

Late-Weichselian ice sheets in Arctic and Pacific Siberia

Abstract Interpretation of Space images coupled with field data on glacial geomorphology and glacial geology of Northern Eurasia have provided compelling evidence for a continuous Late Weichselian ice sheet covering the entire Arctic margin of the continent. In addition to the Scandinavian ice sheet, three ice sheets of the same order — the Karan, East Siberian and Beringian — are identified within the major Eurasian ice sheet. Also, there is evidence and other considerations suggesting a former ice sheet in the Sea of Okhotsk. Ice-spreading centers of the ice sheets were situated on the continental shelves off the Siberian coasts, thus we can term the ice sheets ‘Siberian’. So far, the conventional stratigraphic approach to the problem of Siberian glaciation has proven fruitless and yielded nothing but uncertainty, while geomorphological studies have discovered a wealth of glacial landforms in Arctic Siberia. It was these landforms and their spacing that made the existence of former Siberian ice sheets evident. The East Siberian ice sheet rested on the shelves of the eastern Laptev and East Siberian Seas, and its flow was directed radially, including up the Yana and Indigirka Rivers. The Beringian ice sheet was grounded on the Chukchi-, Bering-, and Beaufort Sea shelves, overriding the Chukchi and Seward Peninsulas from the north and flowing through the Bering Strait. It was continued by a thick floating ice shelf buttressed by the submarine Aleutian-Commander Ridge. The Okhotsk ice sheet was grounded on the Okhotsk shelf. Specific gemorphic signatures of marine ice sheets — the ‘glacially cut corners’ — have been identified on all promontories jutting out into the Bering and Okhotsk Seas. The Beringian and Okhotsk ice sheets are consistent with the results of deep-sea drilling in the adjacent North Pacific during Leg 145 of D/V JOIDES Resolution.

An Antarctic‐style ice sheet in the northern hemisphere: Toward a new global glacial theory

Abstract New studies suggest that two superlarge ice sheets, composed of a number of terrestrial and marine ice sheets interconnected by floating ice shelves, formed in the northern hemisphere during Late Pleistocene time. The combined ice sheets (the proposed names of which are the North Atlantic or Pan‐Arctic and the North Pacific ice sheets) had areas of 30 and 10.5 million km2 and volumes of 50 and 10 million km3 respectively. Combined Antarctic‐style terrestrial‐marine ice sheets of this type seem to have been typical of all former glaciations. The Eurasian Arctic was dominated by two largely marine ice sheets: the Kara and East Siberian ice sheets. The former was centered on the southern Kara Sea; it invaded both west‐central Northern Siberia and the eastern Barents Shelf and was the largest ice dome in Eurasia. The East Siberian Ice Sheet rested on the floor of the Laptev, East Siberian, and Chukchi seas; its former existence has recently been proved on the basis of the glacial geomorphology of the...