Ninth International Conference on Permafrost ... - IARC Research

More documents

Recommendations

Info

Tides as a Possible Reason for Massive Ice Beds FormationSergey A. Sokratov, German A. RzhanitsynFaculty of Geography, Moscow State University, GSP–1, Moscow, 119991, RussiaIntroductionThe argumentations on the genesis of massive ice bedsdiscovered on wide territories of the Arctic and Subarctichave special meaning for the Russian permafrost scientificcommunity. The critical point of the ongoing discussionsturns out to be either marine or glacier origin of the massiveice beds, since this affects in whole the interpretation ofthe paleo-history of Northern Eurasia (Solomatin 2005).It should be emphasized that the massive ice beds ofinterest (plastovye l’dy) neither are a part of the Russian groundice classification (Popov et al. 1985) nor a singled-out type ofground ice in the IPA glossary (van Everdingen 2005). Froma terminology viewpoint, different genesis of the massive icebeds at different sites is the natural expectation. Recently,these massive ice beds are being classified by expectedgenetic types (Shpolyanskaya & Streletskaya 2004).However, the disagreement on either buried or in-site originof seaside massive ice beds, especially, still exists due touncertainties in explanations of the existence of salinefreemassive ice lenses incorporated into salted marinesediments, the isotopic difference between the sea waterand the massive ice lenses, and particularly the morphologyinterpreted as the deformation markings on some of themassive ice beds (Solomatin 2005).Leaving aside the fundamental question of ice sheetexistence over Northern Eurasia, the paleo-climate signalenclosed into the massive ice beds and their bearing stratais the product of the processes responsible for the formation,growth, and melt of an ice body. Since most of the knownmassive ice beds are found in the former or presentcoastal zones (Shpolyanskaya & Streletskaya 2004), it isworth considering coastal zones-specific processes as thepossible participants in the massive ice beds formation andmaintenance. The background of the reported investigationwas to test the possibility that periodic natural fluctuations ofgroundwater level due to upthrust of groundwater runoff bytides play a part in ice lens formation. Such a mechanism, withfavorable groundwater freezing climate conditions, allowsfor formation of saline-free ice lenses from groundwaterwith close to the atmospheric precipitations isotopic contentin the saline marine sediments.Tides and Groundwater RunoffThe result of field investigations at the White Seacoast (Pon’goma) was the confirmation of the dependenceof groundwater level variation on the tidal regime, at least inthe case of sandy ground and tides up to 2 m (Fig. 1).The dependence observed by measurements in dug pitsby automatic water level sensors was pronounced up to tensof meters from the shoreline. Figure 1 shows the results ofFigure 1. The correlation between sea level variation andgroundwater level variation.the groundwater level measurements in a dug pit 7 m fromwater’s edge at maximal tide, 1 m above the maximal sealevel. The variation is extracted from the overall changeof groundwater level due to variability in precipitationand snowmelt, and represents about 10% of the overallvariability. The delay between the extremums of sea andgroundwater level variations is approximately 4 hr. Suchdependence was not observed in another area of the coastalzone with clayey and peat grounds, despite high (up to 9 m)tides (Mezenskaya Bay, White Sea).The field observations also demonstrated strong seasonalvariability of the dependence of the groundwater levelvariability on tides up to disappearance of the propagationof the tides’ signal at distance from the shoreline, caused bythe amount and unevenness of the groundwater runoff. Animportant role in the tides’ signal propagation was foundto belong to the formation of an impermeable seasonallyfrozenground layer near the soil surface. Therefore, itwas concluded that the relation between the tides and thegroundwater level variation is different for territories withdifferent texture of soil, is determined by the amount of thegroundwater runoff and by the activity of tides, and variesconsiderably in dependence on the soil freezing conditions.A study of thick deposits of ground ice in exposure at theUral coast of Baidaratskaya Bay revealed their polygeneticorigin. The analysis of the structural characteristics of theice, however, suggested the possibility of participation of theproposed mechanism in ice lenses formation.Groundwater Level Variation and Ice LensGrowthThe laboratory studies included modeling of thegroundwater level change, periodically introduced upwardinto two-layer samples with unidirectional frost penetration297
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 tAcknowledgmentsThe project was supported by the Russian Foundation ofBasic Research, grant No. 05-05-65115.Figure 2. Structure of the ice schlieren near the boundary of the twolayers of a sample. The top layer is montmorillonite; the bottomlayer is fine sand.from top downward. The top layers were made from differentclay and the bottom layer, from sand (Fig. 2).The ice-rich horizon and ice lens (up to 1.5 cm thick)were formed near the boundary between the layers duringseveral tens of cycles of the alternating groundwater levelvariation. The microstructure of the ice filling the fracturesin the clay is characterized by subparallel to the schlierenlayering related to several stages of ice crystal formationand growth inside the fractures. The ice crystals normallyhad a columnar structure with the long axes in the heat fluxdirection regardless of the variation in orientation of theschlieren (Fig. 2a). The gas inclusions in central parts ofthe schlieren were mainly represented by large elongatedallocations, and at the peripheral parts, by chains of smallbubbles. Large elongated bubbles were usually orientedsubperpendicular to the schlieren’s boundaries. Largemultilayered schlieren also contained thin chain-like gasinclusions parallel to the schlieren’s strike which, togetherwith microcracks, confirm rupturing of already existent iceschlieren and repetitive water freezing inside them (Fig. 2b).The arrangement and form of ice crystals and gas inclusionscorresponds to the structural specific of the intrusive iceformed from small amounts of inlet water and is alike tothose of the natural massive ice lenses.Referencesvan Everdingen, R.O. (ed.). 2005. Multi-Language Glossaryof Permafrost and Related Ground-Ice Terms.<strong>International</strong> Permafrost Association, 278 pp.Golubev, V.N. 2007a. Periodicheskie izmeneniya urovnyamorya kak faktor formirovaniya plastovykh zalezheil’da. (Periodic variations of sea level as a factor ofthe tabular ice formation.) Kriosfera Zemli (EarthCryosphere) XI(1): 52-61Golubev, V.N. 2007b. Rol’ morskikh gidrodinamicheskikhprotsessov v formirovanii zalezhei plastovykhl’dov na arkticheskom poberezh’e. (The roleof sea hydrodynamic processes in formation ofthe massive ice beds deposits at Arctic shore.)Materialy Glyatsiologicheskikh Issledovanii (Data ofGlaciological Studies) 102: 32-40.Popov, A.I., Rozenbaum, G.E. & Tumel’, N.V. 1985.Kriolitologiya. (Cryolithology). Moscow: MoscowState University, 239 pp.Shpolyanskaya, A.N. & Streletskaya, I.D. 2004.Geneticheskie tipy plastovykh l’dov i osobennosti ikhrasprostraneniya v Rossiiskoi Subarktike. (Genetictypes of massive ice beds and specific of theirdistribution in Russian Subarctic.) Kriosfera Zemli(Earth Cryosphere) VIII(4): 56-71.Solomatin, V.I. 2005. Gletchernyi led v kriolitozone.(Glacier ice in cryolithozone.) Kriosfera Zemli (EarthCryosphere) IX(2): 78-84.ConclusionsThe results of the studies verified the possibility of theformation of ice-saturated ground horizons by periodicvariation of the groundwater level, with the tides as a possiblereason of such periodic variation. A considerable numberof conditions required for realization of such a mechanismdetermines spatial limitations of its manifestation at eachtime interval. However, long-term variation of sea levelagainst the background of climate change concedes action ofthe mechanism in past and allows explanation of recent-timedistribution of the massive ice deposits over wide territoriesand at considerable distances from the recent-time Arcticshoreline (Golubev 2007a, 2007b).298
Page 1:
NICOP 2008 Ninth <
Page 6 and 7:
ContentsPreface ...................
Page 8 and 9:
Mapping and Modeling the Distributi
Page 10 and 11:
Satellite Observations of Frozen Gr
Page 13 and 14:
xiiIce Wedge Thermal Regime in Nort
Page 15 and 16:
xivPermafrost Response to Dynamics
Page 17 and 18:
xvi
Page 19 and 20:
NICOP SponsorsUniversitiesUniversit
Page 22 and 23:
Deep Permafrost Studies at the Lupi
Page 24 and 25:
Effect of Fire on Pond Dynamics in
Page 26 and 27:
Cryological Status of Russian Soils
Page 28 and 29:
Acoustical Surveys of Methane Plume
Page 30 and 31:
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 82 and 83:
The Combined Isotopic Analysis of L
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
Page 109 and 110:
Ni n t h In t e r n at i o n a l Co
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Ni N t h iN t e r N at i o N a l Co
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Ni N t h iN t e r N at i o N a l Co
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268: Ni n t h In t e r n at i o n a l Co
Page 317: Ni n t h In t e r n at i o n a l Co
Page 369 and 370:
Page 371 and 372:
Page 373 and 374:
Page 375 and 376:
Page 377 and 378:
Page 379 and 380:
Page 381 and 382:
Page 383 and 384:
Page 385 and 386:
Page 387 and 388:
Page 389 and 390:
Page 391 and 392:
370Huang, B. 339Hugelius, G. 105, 1
Page 393:
372
show all

Ninth International Conference on Permafrost ... - IARC Research

Create successful ePaper yourself

Delete template?

Save as template?