Middle and Late Pleistocene climate and continentality inferred from ice wedges at Batagay megaslump in the Northern Hemisphere’s most continental region, Yana Highlands, interior Yakutia

Ice wedges in the Yana Highlands of interior Yakutia—the most continental region of the Northern Hemisphere—were investigated to elucidate the winter climate and continentality during the Middle to Late Pleistocene. The Batagay megaslump exposes ice wedges and composite wedges that were sampled from three cryostratigraphic units: the lower sand unit of Marine Isotope Stage (MIS) 6 age, the upper Ice Complex (Yedoma) and the upper sand unit (both MIS3 to MIS2). A terrace of the 20 nearby Adycha River provides a Late Holocene (MIS1) ice wedge that serves as a modern endmember for analysis. Stableisotope values of ice wedges in the MIS3 upper Yedoma Ice Complex at Batagay are more depleted (mean δO about ‒35‰) than those from 17 other ice-wedge sites across coastal and central Yakutia. This observation points to lower winter temperatures and, therefore, higher continentality in the Yana Highlands during MIS3. Likewise, more depleted isotope values compared to other sites in Yakutia are found in Holocene wedge ice (mean δO about ‒29‰). Ice-wedge isotopic signatures 25 of the MIS6 lower sand unit (mean δO about ‒33‰) and of the MIS3-2 upper sand unit (mean δO from about -33 to -30‰) are less distinctive regionally and preserve traces of fast formation in rapidly accumulating sand sheets and of post-depositional fractionation.


Introduction
Interior Yakutia is currently the most continental region of the Northern Hemisphere.At Verkhoyansk, the pole of cold of the Northern Hemisphere, mean monthly air temperature ranges exceed 60°C and absolute temperatures ranges can exceed 100°C landscape and exposes a sequence of permafrost deposits at least 60 m thick, with underlying bedrock cropping out in places (Kunitsky et al., 2013).The slump has formed during recent decades, with increasing headwall retreat rates of up to 30 m per year.In 2016 it reached a width of 840 m and a total area of >70 ha (Günther et al., 2016).
The slump exposes Holocene and Pleistocene permafrost formations ranging in age from MIS 6 (or older) to MIS 1 (Ashastina et al., 2017;Murton et al., 2017;Ashastina et al., 2018).Above bedrock and a basal diamicton, four major cryostratigraphic units contain ice wedges (Figure 3).The lowest unit is a pebbly dark sand 3-7 m thick, with ice wedges at least 2-3 m high and 1 m wide truncated by a thaw unconformity.This lower Ice Complex has neither been dated nor sampled previously for wedge ice.
Above it is the lower sand unit, reaching 20 to 30 m in thickness and composed of yellowish pore-ice cemented (fine) sand with grey horizontal bands.It contains tall, narrow syngenetic ice wedges up to 0.5 m wide.The middle part of the unit was dated to 142.8±25.3 and >123.2 ka by optically-stimulated luminescence (OSL) and to 210.0±23.0ka by infrared stimulated luminescence (IRSL) (Ashastina et al., 2017), pointing to its deposition during MIS6 or even MIS7.A thin organic-rich layer of silty sand with abundant woody debris (in lenses up to 3 m thick) overlies a distinct erosional surface near the top of the lower sand unit.A wood fragment yielded a conventional radiocarbon age of 49.32±3.15 14C ka BP, outside of the range of calibration (Murton et al., 2017), though palaeoecological analysis points to a Last Interglacial age for the organic material (Ashastina et al., 2018).
The overlying upper Ice Complex is 20-40 m thick and dominated by huge syngenetic ice wedges up to few metres wide and at least several metres high within silty and sandy deposits.Finite radiocarbon ages from 49.0±2.0 14 C ka BP to 12.66±0.05 14C ka BP (Ashastina et al., 2017) indicate sedimentation gaps or erosive events and reveal a MIS3 to late MIS2 age for the upper part of the upper Ice Complex.This unit has numerous chronostratigraphic analogies in the coastal lowlands of northern Yakutia, i.e. the Yedoma Ice Complex (Schirrmeister et al., 2011b;Murton et al., 2015).The upper Ice Complex forms the highest Pleistocene stratigraphic unit in the upper central part (upslope) of the slump headwall, whereas downslope towards the slump mouth it is overlain and partially grades into the upper sand unit (Figure 3).
The upper sand is up to about 20 m thick and consists of pore-ice cemented brown to grey sand with narrow (≤ 0.5 m wide) syngenetic ice wedges and composite wedges.Radiocarbon ages between 36.30±0.70 14 C ka BP and 26.18±0.22 14C ka BP (Ashastina et al., 2017;Murton et al., 2017) indicate deposition during MIS3 and MIS2, similar to the upper Ice Complex, but in a more complex spatiotemporal pattern, likely due to varying palaeotopography and sediment supply.
A near-surface layer 1-1.5 m thick of brown sand and modern soil covers the sequence.This layer was dated to 0.295±0.03ka 14 C BP (Ashastina et al., 2017).Distinct (thermo-)erosional contacts can be found between the lower Ice Complex and the lower sand, the lower sand and the upper Ice Complex and below the near-surface layer.
According to Murton et al. (2017) exposed floodplains of proximal rivers such as the Batagay and Yana, within 2 and 10 km, respectively, of the slump are the assumed major source of the sediments exposed in the headwall, which implies upslope directed transport by wind.Periglacial, proluvial, or nival processes on nearby hillslopes may also have contributed to sediment supply (Ashastina et al., 2017).The second study site, chosen as a Late Holocene reference, is the actively eroding Holocene to recent bank of a small cut-off channel of the Adycha River, about 40 km east of the Batagay megaslump (Figure 1).The Adycha site is located about 3 km upstream of the 60-65 m high and 1.2 km long river bluff at Ulakhan Sullar (Kaplina et al., 1983;Sher et al., 2011;Germonpre et al., 2017).Organic-rich silty sands of alluvial origin are exposed in the Adycha riverbank section.

Fieldwork
Cryostratigraphic observations of ice wedges, composite wedges, unit contacts and sediments at the Batagay megaslump and a terrace of the Adycha River provided a framework with which we selected samples.A total of six ice wedges and composite wedges from the lower sand, the upper Ice Complex and the upper sand were described in detail and sampled at two sections of the slump (Figure 2, Figure 4, Figure 5).The lower Ice Complex was inaccessible due to dangerous outcrop conditions, and no wedges were observed in the near-surface layer.At the Adycha River, we sampled a single ice wedge.Ice samples about 4 cm wide, mostly in horizontal profiles, were obtained by chain saw.Details about the studied ice and composite wedges are given in Table S1.The ice samples were melted on site in sample bags, and the meltwater filled up 30 ml PE bottles that were then then tightly closed and stored cool until stable-isotope analysis.
In addition, water from small streams draining the slump was sampled in several parts of the slump floor and the main outflow stream (n=7) as well as from summer precipitation (n=4).Supernatant water from selected Batagay sediment samples (n=9) was taken for stable-isotope analysis of intrasedimental pore and segregated ice.

Stable-isotope analysis
The stable oxygen (δ 18 O) and hydrogen (δD) isotope ratios of all samples were determined at the Stable Isotope Laboratory of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research in Potsdam, using a Finnigan MAT Delta S mass spectrometer with an analytical precision of better than ±0.1‰ for δ 18 O and ±0.8‰ for δD (Meyer et al., 2000).The isotopic composition is expressed in δ per mille values (‰) relative to the V-SMOW standard.The deuterium excess d was calculated as d = δD -8 × δ 18 O (Dansgaard, 1964).In some cases, lateral ice-wedge samples with isotopic values distinctly different from the wedge centres and similar to host sediments due to exchange processes between wedge ice and host sediments were excluded from further analysis.

Radiocarbon dating
Organic material from ice wedges and host sediments was radiocarbon dated at the MICADAS 14 C dating facility of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research in Bremerhaven.The organic material was subjected to chemical leaching and cleaning following the ABA (acid-base-acid) procedure.Material was first submerged in 1 M HCl (for 30 min at 60 °C) to remove carbonate contamination.Following rinsing with Milli-Q water, samples were submerged in 1 M NaOH (for 30 min at 60 °C) to leach out humic acids.The base leaching was repeated for a minimum of 7 times or until no coloring of the solution was evident.Afterwards the material was subjected to a final acid treatment (1 M HCl; 30 min at 60 °C), rinsed to neutral with Milli-Q and dried for a minimum of 12 h at 60 °C.Milli-Q used for cleaning and acid/base solutions was pre-cleaned by liquid-liquid extraction with dichloromethane to remove remaining organic contamination.
Samples were packed in tin capsules and combusted individually using an Elementar vario ISOTOPE EA (Elemental Analyzer).If samples were smaller than approximately 200 µgC, the CO2 produced by combustion with the EA was directly injected into the hybrid ion source of the Ionplus MICADAS using the gas interface system GIS (Fahrni et al., 2013).For larger samples, the CO2 produced was graphitized using the Ionplus AGE3 system (Automated Graphitization System; (Wacker et al., 2010c).The radiocarbon content of the samples was determined alongside reference standards (oxalic acid; NIST 4990c) and blanks (phthalic anhydride; Sigma-Aldrich 320065) using the Ionplus MICADAS dating system (Synal et al., 2007;Wacker et al., 2010a), and blank correction and standard normalization were performed using the BATS software (Wacker et al., 2010b).Results are reported as F 14 C (Reimer et al., 2004) and conventional radiocarbon ( 14 C) ages in year BP.
Several analyses yielded lower 14 C intensities than the blanks included in the respective sequence.In these cases, results are reported as F 14 Csample < F 14 Cblanks.Conventional 14 C ages were calibrated using Oxcal 4.3 (Bronk Ramsey, 2009) based on the IntCAL13 dataset (Reimer et al., 2013).

Field observations of ice wedges
The present study confirms cryostratigraphic observations about ice wedges and composite wedges from earlier studies (Ashastina et al., 2017;Murton et al., 2017) and provides new observations about wedge ice relationships across contacts between the cryostratigraphic units, which are outlines below.
In the lower Ice Complex, ice wedges are truncated by a thaw unconformity, though the toes of some narrow syngenetic composite wedges in the overlying lower sand unit extend down across the contact (Figure S1).The basal contact of the lower Ice Complex was not observed.
In the lower and upper sand units, narrow syngenetic wedges vary in apparent width from a few centimetres to about 0.5 m.
Width commonly varies irregularly with height along individual wedges, sometimes gradually, sometimes abruptly.Wedge height varies from a few metres to at least 12 m.Wedges tend to be oriented approximately at right angle to colour bands in the sand, such that wedges in the upper sand unit-whose bands dip downslope, parallel to the ground surface-are characteristically subvertical, with their tops inclined downslope (Figure S2).The wedge infills grade between end members of ice-wedge ice and icy sand wedges, with slightly sandy ice-wedge ice (i.e.composite wedges) the most common type.A single example of clear ice sharply overlying the shoulder of a composite wedge in the lower sand unit (B17-IW1, Figure 4) contained brown plant remains and round, few-mm diameter organic bodies identified as hare droppings.This ice lacked the foliation characteristic of wedge ice and is interpreted as pool ice.
Near the base of the upper Ice Complex, syngenetic ice wedges, a few metres wide tend to narrow downwards in the lower several metres of the unit and terminate with irregular or flattish or U-to V-shaped toes over a vertical distance of about 1-3 m (Figure S2).At the northeast part of the slump headwall, however, the base of the upper Ice Complex is a sharp contact that cuts down into and truncates bands in the underlying lower sand unit over a vertical distance of up to at least several metres (Figure 3).As a result, the upper ice complex thickens substantially downslope.
The top of the upper ice complex displays a variety of wedge relationships with the overlying upper sand unit (Figure S3).Some wide syngenetic wedges terminate along planar to gently undulating contacts that are horizontal to gently dipping and have apparent widths of about 1-3 m; some taper upward into narrow wedges characteristic of the upper sand unit; some taper irregularly upward, marked by shoulders up to about 0.5 m wide; and some end upwards with a narrow offshoot.These changes occur over a vertical distance of about 1-3 m.
Radiocarbon dating of twigs, Cyperaceae stems and roots from a sediment sample 0.5 m above the truncated ice wedge yielded nonfinite ages of >53,400 and >37,500 14 C yr BP (Table 2).A hare dropping from the ice wedge was dated to 15,792±358 14 C yr BP, which can be only explained by redistribution or contamination.

Upper Ice Complex (MIS3-2)
Two large syngenetic ice wedges from the overlying ice-rich upper Ice Complex in section 2 (Figure 5) in the southern part of the slump show more depleted isotope values as compared to the lower sand unit (Table 1, Figure 6).Ice wedge B17-IW6  Unidentified plant and insect remains from ice wedge B17-IW6 as well as Cyperaceae remains and roots from host sediment at the lowest studied level in section 2, about 26 m below surface, both revealed nonfinite ages (>37,500 14 C yr BP; Table 2).
At the level of about 20 m bs rootlets from the host sediment yielded ages of >37,500 and 47,550±677 14 C yr BP, whereas unidentified plant remains from within ice wedge B17-IW5 were dated to 24,858±536 14 C yr BP.
Two radiocarbon ages (analysed as gas) of small samples of Empetrum nigra leaf, twigs, and Cyperaceae remains from host sediment about 11 m bs are nonfinite, whereas a graphite target yielded an age of 38,348±236 14 C yr BP.

Summer precipitation
The samples of summer precipitation from both sites show much more enriched stable-isotope compositions than the wedges, as expected (Table 1).The samples taken at the Batagay megaslump plot on a co-isotopic regression line of δD = 7.93 δ 18 O + 1.65 (R 2 = 1).Mean values are -14.3‰for δ 18 O, -112.0‰ for δD, and 2.6‰ for d excess (n=4).

Adycha River
Ice wedge A17-IW3 was about 0.3 m wide and sampled about 1.4 m above river level and about 2 m below the ground surface.
Rootlets and larch needles from the host sediment were dated to 213±109 14 C yr BP and confirm the Late Holocene age of the alluvial sediments and the ice wedge.

Chronostratigraphy of the Batagay megaslump
To date, the exceptionally long record of permafrost history under highly continental climate conditions as preserved in the Batagay megaslump is still not entirely established in terms of its geochronology.Previous studies by Ashastina et al. (2017) and Murton et al. (2017) provide the general differentiation into four main units overlain by Late Holocene cover deposits, which are the lower Ice Complex (pre-MIS6), the lower sand unit (MIS7-6), the upper Ice Complex (MIS3-2) and the upper sand unit (MIS3-2).Thaw unconformities as observed in sampled sections of this study (Figure 4, Figure 5), but also in previous studies question the completeness of the archive.Such (thermo-)erosional features are often observed in late Quaternary permafrost chronologies (e.g.Wetterich et al., 2009) and most likely caused by intense permafrost degradation during warm stages such as the Last Interglacial with widespread thermokarst (e.g.Kienast et al., 2011), but might also relate to palaeotopography.
The Batagay megaslump exposes the single stratigraphic units in different contacts.Its complex structure, the rapid erosion and the huge dimensions, however, hold potential to identify additional records and units in future studies.With the present study and additional radiocarbon dating, further confidence of the existing stratigraphy is reached although the wedge-ice derived age information asks for careful interpretation.Due to the formation mechanism and downward directed growth of wedge ice, organic remains from inside the ice are commonly younger than those of the host deposits at the same altitude (sampling depth).The risk to date redeposited organic material, that entered into or later froze onto the surface of ice recently exposed in a slump, is always given, in particular in erosional features such as a slump with gullies.It can be seen in the lower sand unit (Figure 4) where an age of about 16 14 C ka BP was obtained from the ice wedge, while radiocarbon dates of the host deposit are infinite and luminescence ages reach 142.8±25.3ka and >123.2 ka by OSL as well as 210.0±23.0ka by IRSL (Ashastina et al., 2017).
A distinct layer of wood and other plant remains up to 1.5 m thick and traceable along the exposure is situated above the lower sand unit and the upper Ice Complex.Radiocarbon dating of this layer revealed an infinite radiocarbon age of >44 14 C ka BP (Ashastina et al., 2017) as well as an out of calibration age of 49.32±3.15 14C ka BP (Murton et al., 2017).The palaeobotanic The expected difference between ice-hosted and sediment-hosted ages of the same sample depth is clearly seen in the upper Ice Complex, where organic remains from the ice wedge are dated to about 25 14 C ka BP and the host deposits yield nonfinite to about 48 14 C ka BP ages (Figure 5).However, even though the age offset is very large and a contamination of the dated sample in the field cannot be excluded, such information may be reliable and lies within the previously dated overall accumulation period of the upper Ice Complex between about 49 and 13 14 C ka BP (Ashastina et al., 2017;Murton et al., 2017).
The new radiocarbon ages from the upper sand unit largely confirm the assumed accumulation period of this unit from about 36 to 26 14 C ka BP (Ashastina et al., 2017;Murton et al., 2017), but predate it by about 2000 years, at least with a date of about 38 14 C ka BP and nonfinite ages of >37.5 14 C ka BP from the host deposits.We note that the upper sand has been studied at two different sites of the slump in different altitude levels (north-northeast of the central headwall (Ashastina et al., 2017;Murton et al., 2017) and together with the upper Ice Complex more downslope in the southern part of the slump, (Figure 2), which complicates the correlation of dating results from different sampling sites.Furthermore, close to our section 2, the upper sand could not clearly be differentiated from the upper Ice Complex during fieldwork in 2014 (Ashastina et al., 2017).Hence, the more or less simultaneous accumulation of both the upper Ice Complex and the upper sand unit during MIS3-2 but the differing spatial distribution in the slump highlights the importance of paleo-topography in a hillslope setting and varying sediment sources and velocities of deposition and require future sampling and analysis at higher vertical resolution.
Interestingly, no indications for an upper sand layer have been found in the topmost part of the modern headwall.Additionally, there are no significant Holocene deposits exposed at all in the upper part of the slump.However, carcasses of Equus lenensis and baby Bison priscus (dated to 4.45±0.35ka 14 C BP and 8.215 +0.45/-0.40ka 14 C BP) were found at the exit of the slump (Murton et al., 2017).These observations may be related to (a) the palaeo-topographic situation and transport and deposition regimes of windblown dust during MIS3-1, likely decreasing upslope, (b) widespread permafrost degradation since the Late Glacial Early Holocene transition, and/or (c) changed hydrological and vegetation patterns in the Holocene preventing transport and/or deposition of windblown dust.
The lower Ice Complex is not dated so far.Given the dating results of the overlying lower sand unit it may correspond to the Yukagir Ice Complex from Bol'shoy Lyakhovsky Island, which has been dated by radioisotope disequilibria ( 230 Th/U) in peat to 178±14, 221±27 ka (Wetterich et al., in revision) and to 201±3 ka (Schirrmeister et al., 2002).Hence this unit most likely has survived two interglacials.

Cryostratigraphy at the Batagay megaslumpimplications for ice-wedge growth regime
The shape and composition of the wedges in the Batagay megaslump correspond to the assumed genesis of the respective units and may also provide palaeoclimate information (Table 3).Both the lower and upper Ice Complex units are characterized by ice wedges up to several m wide, whereas both the lower and upper sand units contain tall narrow wedges.The former indicates more stable surface conditions with lower accumulation rates and sufficient melt water supply during the formation of both Ice Complexes that allowed more horizontal growth of ice wedges.The tall narrow wedges of both sand units, in contrast, point to rapid upslope directed aeolian deposition of sediments and, therefore, a predominant vertical ice-wedge growth in persistent polygonal patterns.The downslope inclination of narrow syngenetic wedges in the upper sand unit indicates upward growth subvertically at right angle to the aggrading depositional surface, a hillslope.The tall and narrow wedges in the sand units are similar in size and shape to chimney-like sand wedges in thick aeolian sand sheets in the Tuktoyaktuk Coastlands of western Arctic Canada, attributed to rapid aggradation of aeolian sand and rapid wedge growth (Murton and Bateman, 2007).
Ice wedges in the lower sand unit point to moister conditions than the composite wedges in the upper sand unit, which imply dry conditions with only little melt water supply.However, as most ice wedges exhibit a significant sediment content, a steady supply of windblown sediment and a rather thin snow cover during ice-wedge formation is likely.
At the top of the upper Ice Complex, ice wedges tend to narrow and partly transform into narrow composite wedges of the upper sand unit (Figure S3).This indicates a rather gradual change of the deposition regime towards higher sedimentation rates and possibly lower melt water supply due to drier conditions.Interestingly the polygonal pattern has not been affected by this change, as indicated by the consistent frost-cracking positions.The upward transition of wedges from the upper ice complex to upper sand unit, however, was interrupted episodically by thaw, producing a number of thaw unconformities at different depths.In contrast, the erosional event truncating the lower Ice Complex seems to have changed the polygonal pattern in which the lower sand unit has been deposited.
A major erosional surface attributed to gullying by water flowing down a palaeo-hillslope is inferred from the large concaveup lower contact of the upper ice complex in the northeast part of the headwall (Figure 3).Numerous gullies on the present hillslope near the megaslump are indicated on satellite images between 1968 and 2010 reported by Kunitsky et al. (2013), which suggests that gullies are characteristic landforms of such terrain under present environmental conditions.Water is supplied to such gullies by snowmelt in spring and rainfall and melt of ground ice in summer.Erosion of the underlying lower sand unit provided substantial accommodation space for development of an unusually thick upper ice complex with wide ice wedges above it.Stratigraphically, this erosional surface is at a similar level as the upper woody trash layer that is thought to be of last interglacial age (Ashastina et al., 2017;Ashastina et al., 2018), which in turn suggests that the erosion also probably took place during warm (interglacial) conditions.

Yana Highlands' ice-wedge stable isotopesregional palaeoclimate implications
Unfortunately, no comprehensive modern precipitation stable-isotope data are available for the Yana Highlands.The nearest sites with available data are Zhigansk about 500 km to the west (Kurita, 2011), Tiksi about 500 km to the northwest (Kloss, 2008) and Yakutsk about 650 km to the south (Kloss, 2008;Papina et al., 2017).These sites show similar isotopic characteristics for the cold season (October to March).Mean δ 18 O values decrease along the north-south transect from about -29‰ in Tiksi to -31‰ in Yakutsk, d excess varies strongly without a clear geographical pattern and shows values between about 8 and 15‰.In general, the mean winter isotopic data plot around the GMWL.However, these sites are characterized by  (Popp et al., 2006).The exceptional ice wedges from the Bykovsky Peninsula (Meyer et al., 2002a) even reach d values of 16‰.In summary, Holocene ice wedge d excess values do not show a clear spatial pattern that is readily interpreted in terms of moisture sources or continentality.

Conclusions and outlook
Our stable-isotope data clearly show that winter temperatures in the Yana Highlands during MIS 3, represented by the upper Ice Complex (Yedoma) at Batagay, and the Holocene were significantly lower than at other ice-wedge study sites in coastal and central Yakutia.This indicates the persistence of enhanced continentality of the Yana Highlands region during at least part of the Late Pleistocene in western Beringia and during the Holocene.The stable-isotope data from narrow composite wedges of the upper sand unit (MIS3-2) and an old ice wedge from the lower sand unit (MIS6) are less indicative and require additional studies.
High-resolution systematic sampling and dating now needs to be carried out for all cryostratigraphic units of the Batagay permafrost sequence to validate our findings of increased continentality during MIS3 and the Holocene, to improve the temporal resolution of the Batagay ice-wedge record, and to elucidate the palaeoclimatic history from other time slices.Of particular interest are the lower and uppermost parts of the upper Ice Complex, likely representing MIS4 and MIS2 stadials, as well as the lower Ice Complex, possibly representing late MIS7 or early MIS6.To establish reliable ice-wedge chronologies, radiocarbon dating should include macro remains, dissolved organic carbon and CO2 from gas bubbles (Lachniet et al., 2012).
Clim.Past Discuss., https://doi.org/10.5194/cp-2018-142Manuscript under review for journal Clim.Past Discussion started: 30 October 2018 c Author(s) 2018.CC BY 4.0 License.proxydata indicate warm climate.Hence the unit is aligned to the Last Interglacial(Ashastina et al., 2018) that caused particular thaw of the underlying lower sand unit and formed a discordance in the sequences.
Clim.Past Discuss., https://doi.org/10.5194/cp-2018-142Manuscript under review for journal Clim.Past Discussion started: 30 October 2018 c Author(s) 2018.CC BY 4.0 License.2018).In contrast, in the Yana Highlands the mean d value of 6‰ is lower compared to the MIS3, whereas d values in central Yakutia (between 6 and 11‰) are rather similar to MIS3 values

Table 1 .
Stable isotope (δ 18 O, δD and d excess) minimum, mean and maximum values, standard deviations as well as slopes and intercept in the δ 18 O-δD diagram for all ice and composite wedges, intrasedimental ice, outflow water and rain water, respectively.

Figure 2 .
Figure 2. Overview photograph of the Batagay megaslump showing the study sites of (Ashastina et al., 2017; Murton et al., 2017) and this study.Photograph taken by Alexander Gabyshev in 2015.

Figure 3 .
Figure 3. Panoramic photograph of the Batagay megaslump with main stratigraphic units and approximate sampling locations of ice wedges (blue arrows).Furthermore, red circles and numbers indicate the approximate sampling locations of ice wedges used by (Vasil'chuk et al., 2017).

Figure 6 .
Figure 6.Co-isotopic δ 18 O-δD diagram of ice wedges and intrasedimental ice sampled at the Batagay megaslump and the Adycha River.Furthermore, the data of the Batagay megaslump outflow samples are shown which display an integrated signal of the entire Batagay permafrost sequence and modern precipitation.5

Figure 9 .
Figure 9. Map of mean d data from Siberian ice wedges attributed to the Kargin MIS3 interstadial (about 50 to 30 ka), Site IDs are given in Figure 7 and further details in TableS2.

Table 2 . Radiocarbon ages of organic remains in ice wedges (sample ID includes IW) and host sediments of the Batagay megaslump and at the Adycha River. The samples were radiocarbon dated as gas targets (Lab ID ends with 1.1) and graphite targets (Lab ID ends with 2.1). Sample ID Depth (m bs) Lab ID F 14 C Radiocarbon age (yr BP) Calibrated age 95.4% (cal yr b2k) Dated material Remarks Batagay megaslump
Clim.Past Discuss., https://doi.org/10.5194/cp-2018-142Manuscript under review for journal Clim.Past Discussion started: 30 October 2018 c Author(s) 2018.CC BY 4.0 License.