Ninth International Conference on Permafrost ... - IARC Research

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The Combined Isotopic Analysis of Late Quaternary Ice Wedges and Texture Ice atthe Lena-Anabar Lowland, Northern SiberiaAlexander DereviaginMoscow State University, Faculty of Geology, Vorobievy Gory, 119899, Moscow, RussiaHanno MeyerAlfred Wegener Institute for Polar and Marine Research, Research Unit Potsdam,Telegrafenberg A43, 14473 Potsdam, GermanyAlexander ChizhovMoscow State University, Faculty of Geology, Vorobievy Gory, 119899, Moscow, RussiaDiana MagensAlfred Wegener Institute for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, GermanyIntroductionDifferent types of ground ice are fed by meteoric watersources and are considered to be a unique archive of paleoenvironmentaland paleoclimatic information (Mackay 1983,Meyer et al. 2002). The isotopic signal of an ice wedge isindicative for winter temperatures. Texture ice (both segregatedand pore ice) may be assumed as a mixture of summerand winter precipitation. Isotope variations within sedimentcolumns are difficult to interpret in paleotemperature terms,because of various processes involved such as seasonalityof precipitation, amount of rain and snow feeding the activelayer, fractionation during evaporation, melting and freezingmay influence its isotopic composition. This study focuseson the combined isotopic analysis of Late Quaternary icewedges and texture ice in an ice-rich sedimentary complexnamed Ice Complex. The isotopic composition (δ 18 O, δD) ofground ice dating to ca. 60 ka was studied in the frameworkof Russian-German multidisciplinary research expeditionsat the Laptev Sea coast.Study Sites and MethodsThe investigations were carried out at two sites locatedin the Lena-Anabar lowland at the Laptev Sea coast atBykovsky Peninsula (eastern part of Lena Delta): atMamontovy Khayata outcrop, 71°60′N, 129°20′E (site 1)and at Cape Mamontov Klyk, 73°36′N, 117°10′E (site 2).The region is characterized by a continental Arctic climate.Mean annual air temperatures (MAAT) at site 1 are about-14°C, mean January temperatures (T J) are about -34°C andmean winter temperatures (T w) are about -22°C (data ofTiksi). MAAT at site 2 are about -15°C, T Jare about -33°C,and T ware about -23°C (data of Cape Terpey-Tumasa).Annual precipitation reaches 300 mm, with a maximum(about 75%) in summer. The region belongs to the zone ofcontinuous permafrost with a thickness of about 300–500m and mean annual ground temperature around -12°C. Thecoastal lowland is characterized by widespread Ice Complexremains, composed of ice-rich silty fine-grained sand withpeaty paleosol horizons and huge syngenetic polygonalice wedges (heights of 20–40 m and widths of 2–6 m) andcolumns of frozen sediments (width of 2–4 m) with belt-likecryostructure.The formation of Late Pleistocene Ice Complex is usuallyassociated with Karginsky and Sartansky periods of theRussian stratigraphy, which correspond to MIS-3 and MIS-2of the global classification. According to AMS dates, IceComplex formation at Bykovsky Peninsula was between58.4 ka (at sea level) and 12.2 ka BP (Schirrmeister et al.2002). At Cape Mamontov Klyk, Ice Complex formationtook place between 31–28 ka and 10.7 ka BP (Schirrmeisteret al. 2008). At both sites, Ice Complex is partly covered by a2 m thick horizon of peat-rich, silty sediments with Holoceneice wedges. Holocene ground ice was also studied in alases,thermo-erosional and river valleys.The investigations are based on the combined applicationof stable isotopes to both ice wedges and texture ice sampledin parallel. Measurements of isotope composition (δ 18 O, δD)were carried out at the Alfred Wegener Institute in Potsdam.The stable isotopic composition is given in ‰ vs. V-SMOWstandard. The 1σ errors for H and O isotopes are better than0.8‰ and 0.10‰, respectively.Results and DiscussionThe available data of isotope analyses are presented inTable 1. Both wedge and texture ice differs considerably intheir isotopic composition between Holocene and Pleistocene,with 3–8‰ lower δ 18 O in Pleistocene ice following theglobal warming trend. The isotopic composition of bothLate Pleistocene wedge and texture ice is very close at site 1and site 2. This can be evidence both of the similarity of icecomplex formation and climatic conditions in the region.The mean δ 18 O of ice wedges differs by 0.1‰ in Sartansky(MIS-2) time, and by 1.6‰ in Karginsky (MIS-3) timebetween both sites. For texture ice, the differences areabout 0.1‰ in Karginsky time. In Holocene, differences inmean δ 18 O reach about 3‰ for ice wedges and 0.7‰ fortexture ice between both sites. The observed differences ofHolocene ice wedges are likely the result of different agesof the sampled ice wedges at sites 1 and 2. At site 1, manyEarly Holocene ice wedge samples were taken at the top ofthe Ice Complex.The ice wedge isotopic composition is similar in Karginskyand Sartansky with more negative minimum values (of -33.9to -34.9‰) in Karginsky time. This leads to the assumption61
Ni n t h In t e r n at i o n a l Co n f e r e n c e o n Pe r m a f r o s tTable 1. Isotopic composition (‰) of ice wedges and texture ice:mean (in bold)/min./max. values). N = number of samples.Ice wedgesTexture iceN δ 18 O δD d exN δ 18 O δD d exSite 1 (Bykovsky Peninsula)Holocene (MIS-1)184 -27.5 -203.5 13.5 14 -20.8 -155.5 11.2-30.2 -224.3 8.5 -23.3 -173.1 7.0-22.5 -168.5 17.8 -17.7 -134.8 15.1Sartansky (MIS-2)178 -29.7 -231.2 6.1-32.1 -253.5 1.9 no data-23.1 -174.5 13.3Karginsky (MIS-3)158 -30.6 -241.3 3.7 40 -23.8 -193.1 -2.5-33.9 -267.5 -3.9 -29.5 -231.7 -11.7-25.6 -208.3 7.9 -18.9 -158.5 14.0Site 2 (Cape Mamontov Klyk)Holocene (MIS-1)54 -24.1 -182.9 10.0 13 -20.1 -150.8 9.7-27.3 -212.6 6.1 -28.2 -204.5 5.2-20.4 -155.5 14.3 -17.2 -130.6 21.4Sartansky (MIS-2)120 -29.8 -234.3 4.5 51 -27.6 -210.3 10.4-31.9 -253.4 0.4 -31.6 -242.1 -7.3-26.1 -199.6 9.4 -19.5 -147.0 24.2Karginsky (MIS-3)62 -29.0 -227.5 4.4 20 -23.7 -186.3 3.6-34.9 -272.2 -0.6 -27.7 -215.3 -16.8-24.0 -180.6 14.6 -16.7 -150.4 19.2that winter conditions in Sartansky were slightly less severethan in Karginsky time.The isotopic composition of texture ice is always lessnegative than the isotopic composition of ice wedges (Table1), because of the influence of summer precipitation (as wellas fractionation effects). Texture ice from Karginsky timeis about -23.7‰ for both sites, whereas Holocene textureice is much heavier (δ 18 O around -20‰), again showingthe similarity between both sites and the relatively warmerHolocene. In contrast, texture ice from Sartansky time ischaracterized by very light isotopic composition (-27.6‰)close to that of ice wedges (-29.8‰). This may correspondto extremely cold summer temperatures and/or a relativelysmaller amount of summer precipitation taking part intexture ice formation at that time. The late glacial maximum(LGM) apparently is visible only in summer.The higher differences between isotopic composition ofice wedges and texture ice (as well as the heavier δ 18 O oftexture ice) in Karginsky time may reflect relatively warmsummer conditions. Additionally, the negative δ 18 O valuesof ice wedges point to severe winter conditions at that time.δ 18 O and δD of ice wedges at both sites are alignedparallel to GMWL with slopes close to 8. This indicates thatthe isotopic composition of initial meteoric water-formedice wedges was not subject to pronounced fractionationprocesses. In contrast, isotopic composition of textureice crosses the GMWL with slopes of 6.8 (site 1) and 7.2(site 2). This is a result of fractionation processes duringevaporation and freezing as well as mixing of both snowmeltand rainwater, also reflected in d excess. In general, lowd-excess values of texture ice point to fractionation duringevaporation and reflect the influence of rainwater enrichedin heavy isotopes. High d-excess values can be considered aresult of fractionation during freezing.ConclusionsThe isotopic records of ground ice correlate well withthe global climatic trend, and show progressive warmingfrom MIS-3 to MIS-1. Ice wedge isotopic composition isindicative for T w. δ 18 O values of texture ice allow estimatingsummer climatic conditions (by comparing with ice wedges).The d excess, well known as an indicator of precipitationsources, also reflects fractionation processes during groundice formation.Negative δ 18 O of ice wedges reflect (stable) cold winterconditions during Karginsky (MIS-3) and Sartansky (MIS-2)time with minimum in Karginsky time. Differences of δ 18 Ovalues between ice wedges and texture ice point to relativelywarmer summers in Karginsky time and colder summerperiods in Sartansky time. This let us believe that the LGMin the region is visible only in summer indicators.The combined isotopic analysis of both ice wedges andtexture ice extends considerably the quantitative and qualitativecapabilities of paleoenvironmental interpretation.ReferencesMackay, J.R. 1983. Oxygen isotope variations in permafrost,Tuktoyaktuk Peninsula area, Northwest Territories.Current Research, Part B, Geological. Survey ofCanada Paper 83-1B: 67-74.Meyer, H., Dereviagin, A., Siegert, C. & Hubberten, H.-W.2002a. Paleoclimate studies on Bykovsky Peninsula,North Siberia. Hydrogen and oxygen isotopes inground ice. Polarforschung 70: 37-52.Schirrmeister, L., Grosse, G., Kunitsky, V., Magens, D.,Meyer, H., Dereviagin, A., Kuznetsova, T., Andreev,A., Babiy, O., Kienast, F., Grigoriev, M. & Preusser,F. 2008. Periglacial landscape evolution andenvironmental changes of Arctic lowland areas duringthe Late Quaternary (Western Laptev Sea coast, CapeMamontov Klyk). Polar Research (accepted).Schirrmeister, L., Siegert, C., Kuznetsova, T., Kuzmina,S., Andreev, A.A., Kienast, F., Meyer, H. & Bobrov,A.A. 2002. Palaeoenvironmental and palaeoclimaticrecords from permafrost deposits in the Arctic regionof Northern Siberia. Quaternary <strong>International</strong> 89:97-118.62
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ContentsPreface ...................
Page 8 and 9:
Mapping and Modeling the Distributi
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Satellite Observations of Frozen Gr
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xiiIce Wedge Thermal Regime in Nort
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xivPermafrost Response to Dynamics
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xvi
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NICOP SponsorsUniversitiesUniversit
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Deep Permafrost Studies at the Lupi
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Effect of Fire on Pond Dynamics in
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Cryological Status of Russian Soils
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Acoustical Surveys of Methane Plume
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Permafrost Delineation Near Fairban
Page 32 and 33: Preparatory Work for a Permanent Ge
Page 34 and 35: A Provisional Soil Map of the Trans
Page 36 and 37: Martian Permafrost Depths from Orbi
Page 38 and 39: Time Series Analyses of Active Micr
Page 40 and 41: Impact of Permafrost Degradation on
Page 42 and 43: DC Resistivity Soundings Across a P
Page 44 and 45: Modeling Thermal and Moisture Regim
Page 46 and 47: A Provisional Permafrost Map of the
Page 48 and 49: Alpine Permafrost Distribution at M
Page 50 and 51: Cryogenic Formations of the Caucasu
Page 52 and 53: Modeling Potential Climatic Change
Page 54 and 55: A Hypothesis: A Condition of Growth
Page 56 and 57: Modeled Continual Surface Water Sto
Page 58 and 59: Freeze/Thaw Properties of Tundra So
Page 60 and 61: Discontinuous Permafrost Distributi
Page 62 and 63: Thermal Regime Within an Arctic Was
Page 64 and 65: Seasonal and Interannual Variabilit
Page 66 and 67: Twelve-Year Thaw Progression Data f
Page 68 and 69: Continued Permafrost Warming in Nor
Page 70 and 71: Landsliding Following Forest Fire o
Page 72 and 73: A Permafrost Model Incorporating Dy
Page 74 and 75: Seasonal Sources of Soil Respiratio
Page 76 and 77: Greenland Permafrost Temperature Si
Page 78 and 79: The Importance of Snow Cover Evolut
Page 80 and 81: The Account of Long-Term Air Temper
Page 84 and 85: Adaptating and Managing Nunavik’s
Page 86 and 87: Human Experience of Cryospheric Cha
Page 88 and 89: HiRISE Observations of Fractured Mo
Page 90 and 91: A Soil Freeze-Thaw Model Through th
Page 92 and 93: Mapping and Modeling the Distributi
Page 94 and 95: First Results of Ground Surface Tem
Page 96 and 97: Historical Changes in the Seasonall
Page 98 and 99: Rock Glaciers in the Kåfjord Area,
Page 100 and 101: Snowpack Evolution on Permafrost, N
Page 102 and 103: Climate Change in Permafrost Region
Page 104 and 105: Maximizing Construction Season in a
Page 106 and 107: Pleistocene Sand-Wedge, Composite-W
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