Pingo Ice Research Articles

Stable oxygen and hydrogen isotope compositions of the Messoyakha and Pestsovoe pingos in northwest Siberia as markers of ice core formation

AbstractPingos are indicators of modern and past conditions of permafrost. In total, 1,620 pingos have been identified on the Yamal and Gydan peninsulas in western Siberia. The main purpose of this study is to consider the distribution of stable isotopes in pingo ice cores formed under conditions of open and closed systems. Two pingos from ice cores of different origin in the continuous permafrost zone of northwest Siberia have been considered: the Messoyaha‐1 pingo (10.5 m in height) and the Pestsovoe pingo (17 m in height). Drilling of the ice core was performed with continuous sampling of an undisturbed frozen core. Ice formation was estimated according to the Rayleigh fractionation in a closed‐system versus an open‐system framework. For the Pestsovoe pingo, a pronounced decrease in δ18O values with corresponding increase in dexc with depth indicates a closed system upon freezing of the lake talik from the top down. For the Messoyakha‐1 pingo, the values of δ18O and δ2Н showed a weak tendency to decrease with depth, with values of dexc varying randomly. Ice that was segregated in the overlying and underlying sediments had similar values of δ18O and δ2Н and a low slope. Isotopically nonequilibrium ice formation was established for ice which had been segregated in a closed system and for ice cores formed in an open to semiclosed system. The vacuum mechanism of water suction from the surrounding lake or lake talik may have played a significant role during the formation of the upper ice core of the Messoyakha‐1 pingo and its additional growth.

Geochemical signatures of pingo ice and its origin in Grøndalen, west Spitsbergen

Abstract. Pingos are common features in permafrost regions that form by subsurface massive-ice aggradation and create hill-like landforms. Pingos on Spitsbergen have been previously studied to explore their structure, formation timing and connection to springs as well as their role in postglacial landform evolution. However, detailed hydrochemical and stable-isotope studies of massive-ice samples recovered by drilling have yet to be used to study the origin and freezing conditions in pingos. Our core record of 20.7 m thick massive pingo ice from Grøndalen is differentiated into four units: two characterised by decreasing δ18O and δD and increasing d (units I and III) and two others showing the opposite trend (units II and IV). These delineate changes between episodes of closed-system freezing with only slight recharge inversions of the water reservoir and more complicated episodes of groundwater freezing under semi-closed conditions when the reservoir was recharged. The water source for pingo formation shows similarity to spring water data from the valley with prevalent Na+ and HCO3- ions. The sub-permafrost groundwater originates from subglacial meltwater that most probably followed the fault structures of Grøndalen and Bøhmdalen. The presence of permafrost below the pingo ice body suggests that the talik is frozen, and the water supply and pingo growth are terminated. The maximum thaw depth of the active layer reaching the top of the massive ice leads to its successive melt with crater development and makes the pingo extremely sensitive to further warming.

Variations of stable oxygen and hydrogen isotopes in the pingo ice core, south of the Gydan Peninsula

The vertical isotopic profile of the pingo Messoyakha-1 (coordinates: 68°30′32″ N, 79°59′53″ E) ice core, obtained in the south of the Gydan Peninsula in the Middle Messoyakha swell. There is no significant variations of the isotopic composition of pingo ice core: δ18О values vary from -14.98 to -16.60‰, δ2Н values vary from -117.9 to -12.8. This small scatter of values is probably the result of intense heaving and rather rapid formation of the pingo. Basing on the features of the pingo, it can be assumed that initially there was a lake of 0.5 km length and 0.3 km width in this site. Then, as a result of water draining to a nearby river, the lake began to dry out and alas, which occupies most of the primary lake area, was formed. Pingo arose during the freezing of the alas under its gradual drying.

Variations of Stable Oxygen and Hydrogen Isotopes in the Ice Core of the Pingo (Southern Part of Gydan Peninsula)

The vertical isotopic profile of the ice core of a Messoyakha-1 bulgunniakh (pingo)—was obtained. The pingo is situated at 68°30′32″ N, 79°59′53″ E, in the southern part of the Gydan Peninsula within the Middle Messoyakha swell. No significant variations were registered in the isotopic composition of the pingo ice core: δ18О varied from –14.98 to –16.60‰ and δ2Н varied from –117.9 to –122.8 ‰. This small range of values probably resulted from intense heaving and rather rapid formation of the pingo. Based on the features of the pingo, it can be assumed that initially there was a lake of 0.5 km length and 0.3 km width at this site. Then, the water drained into a nearby river, the lake began to dry out, and the khasyrey (alas), which occupies most of the former lake area, was formed. The pingo itself arose during the freezing of the alas under its gradual drying out.

Use of stable water isotopes to identify stages of the pingo ice core formation

Te isotopic characteristics of the pingo ice cores are considered. Te distribution of δ18O and δ2H values, dexc, δ18O–δ2H and δ2H–d exc relationships, and the simulation of the distribution of δ18O and δ2H values during the ice formation in a closed system, allowed drawing conclusion about the hydrological conditions and stages of the ice core growth. All pingos (Pestsovoye, Weather, Pingo-20) were formed in draining lake basins in the course of freezing of closed taliks. It is established that the water, which served as a source for the formation of the ice core, was subjected to evaporation still before the ice formation. According to our estimates, the water from which the ice of the Pestsovoye pingo was formed was heavier in values of δ18O and δ2H by 3.9 and 29.7‰, respectively, than the current average annual precipitation in the region. Similarly, for the ice of the core of the Pingo Weather it is 2.9 and 14.5‰, and 5.1 and 27.7‰ for the Pingo-20, respectively. In the ice cores of all considered pingos there is an ice formed in a closed system: in Pingo-20 it is a pure injection ice, while in the Pestsovoye and the Weser ones – the injected-segregated ice. Te frost mounds Pestsovoe and Weser grew under changing hydrological conditions: one part of the ice was formed when there was a free flow of water to the freezing front (open system); the other one – when the water-saturated lenses of the closed talik were frozen (closed system). Te isotopic composition of ice being formed under conditions of a closed system reflects isotopic depletion during freezing and ice formation according to the Rayleigh model. It is expressed in a successive decrease in the values of δ18O and δ2H from the frst portions of ice to the last ones as the freezing continued. Te contrast values of δ18O and δ2H in different parts of the ice being formed in the closed system may be used as an additional tool to identify direction of freezing. In a closed system, the last portions of ice have the greater contrast of the isotope values as compared to the frst portions.

Holocene thermokarst and pingo development in the Kolyma Lowland (NE Siberia)

AbstractGround ice and sedimentary records of a pingo exposure reveal insights into Holocene permafrost, landscape and climate dynamics. Early to mid‐Holocene thermokarst lake deposits contain rich floral and faunal paleoassemblages, which indicate lake shrinkage and decreasing summer temperatures (chironomid‐based TJuly) from 10.5 to 3.5 cal kyr BP with the warmest period between 10.5 and 8 cal kyr BP. Talik refreezing and pingo growth started about 3.5 cal kyr BP after disappearance of the lake. The isotopic composition of the pingo ice (δ18O − 17.1 ± 0.6‰, δD −144.5 ± 3.4‰, slope 5.85, deuterium excess −7.7± 1.5‰) point to the initial stage of closed‐system freezing captured in the record. A differing isotopic composition within the massive ice body was found (δ18O − 21.3 ± 1.4‰, δD −165 ± 11.5‰, slope 8.13, deuterium excess 4.9± 3.2‰), probably related to the infill of dilation cracks by surface water with quasi‐meteoric signature. Currently inactive syngenetic ice wedges formed in the thermokarst basin after lake drainage. The pingo preserves traces of permafrost response to climate variations in terms of ground‐ice degradation (thermokarst) during the early and mid‐Holocene, and aggradation (wedge‐ice and pingo‐ice growth) during the late Holocene.

New data on variations of stable isotopes in the pingo ice core in the southern part of the Tazovsky Peninsula

The aim of this work is to obtain the vertical isotopic profile of the thick Pestsovoe pingo ice core in the southern part of the Tazovsky Peninsula, to determine the oxygen and hydrogen isotopic composition of the ice, and to reveal its formation conditions. Two trends were identified for the isotopic profile of the pingo ice: an insignificant increase of the δ18O (~1.5‰) and δD (~9‰) values at depths of 12–15 m and a gradual decrease of isotopic values by 3.8 and 23‰ for δ18O and δD, respectively, at a depth of 15–26 m. The formation of the pingo ice core in the semiclosed system resulted in fractionation of the isotopic composition of oxygen and hydrogen by more than 4 and 20‰, respectively.

Using noble gas ratios to determine the origin of ground ice

Argon, krypton and xenon have different solubilities in water, meaning their ratios in water are different from those in atmospheric air. This characteristic is used in a novel method to distinguish between ice bodies which originate from the compaction of snow (i.e. buried snow banks, glacial ice) vs. ice which forms from the freezing of groundwater (i.e. pingo ice). Ice which forms from the compaction of snow has gas ratios similar to atmospheric air, while ice which forms from the freezing of liquid water is expected to have gas ratios similar to air-equilibrated water. This analysis has been conducted using a spike dilution noble gas line with gas extraction conducted on-line. Samples were mixed with an aliquot of rare noble gases while being melted, then extracted gases are purified and cryogenically separated. Samples have been analysed from glacial ice, buried snow bank ice, intrusive ice, wedge ice, cave ice and two unknown ice bodies. Ice bodies which have formed from different processes have different gas ratios relative to their formation processes.

Groundwater Hydrology and Stable Isotope Analysis of an Open‐System Pingo in Northwestern Mongolia

ABSTRACTThe first record of stable isotopes through a complete sequence of ice within an open‐system pingo in northwestern Mongolia indicates a complex history of ice formation and pingo growth. A continuous section of ice 32 m long was cored through the centre of Mongot Pingo, and ice cores were analysed for stable isotopes and chemical composition. Two different stable isotope patterns in separate ice sections are identified: 1 open‐system freezing and 2 semi‐closed system (or closed system) freezing. Discharge measurements were observed in 2009 after drilling through pingo ice to artesian sub‐pingo water and compared with data collected from the same pingo in 1968. Approximately 850–950 m3 of sub‐pingo water discharged within 120 h during drilling in both 1968 and 2009, a volume equivalent to about 10 per cent of the current pingo ice volume. Between 1968 and 2009, permafrost (pingo ice) thickened by about 60 cm (1.46 cm per year), from 32.0 to 32.6 m, due to the decrease in sub‐pingo artesian water pressure after water release from the 1968 drilling. The major mechanism for ice formation at this pingo is groundwater artesian pressure, though not continuously. Four major stages of pingo growth after 8790 yr BP are inferred. Copyright © 2013 John Wiley & Sons, Ltd.

Syngenetic Ice Wedges: Cyclical Formation, Radiocarbon Age and Stable Isotope Records by Yurij K. Vasil’chuk, Moscow University Press, Moscow, 2006. 404 pp. ISBN 5‐211‐05212‐9

ABSTRACTThe monograph summarises radiocarbon and stable isotope research on syngenetic ice wedges. The southern boundary of active and inactive ice wedges in Russian permafrost is re‐evaluated and revised. A new model of cyclical growth of syngenetic ice wedges is proposed, involving three cycles in ice‐wedge development: micro‐, meso‐ and macrocycles. Direct dating of syngenetic ice wedges can be carried out by accelerator mass spectrometry (AMS) radiocarbon dating of organic microinclusions and pollen concentrates from ice‐wedge ice. Dating reveals vertical and lateral variation in the age of yedoma at Duvanny Yar (NE Yakutia), one of the key syngenetic permafrost exposures in Eurasia. Radiocarbon ages and oxygen and deuterium isotopic values of syngenetic ice wedges in northern Russia and North America provide insights into palaeoenvironmental history and palaeogeocryology. Syngenetic ice wedges sometimes show complex cryostratigraphic relationships with other types of ice, including massive ice, icing ice and pingo ice. Comparison of isotope records from syngenetic ice wedges with those from Greenland ice cores reveals evidence for Dansgaard‐Oeschger (D/O) events preserved in Siberian permafrost. Copyright © 2013 John Wiley & Sons, Ltd.

Comparison of geophysical investigations for detection of massive ground ice (pingo ice)

Six different geophysical investigations, (1) ground‐penetrating radar, (2) DC resistivity sounding, (3) seismic refraction, (4) very low frequency (VHF) electromagnetic, (5) helicopter borne electromagnetic (HEM), and (6) transient electromagnetic (TEM) techniques, were employed to obtain information on the ice body properties of pingos near Fairbanks, Alaska. The surface nuclear magnetic resonance (NMR) data were also compared from similar sites near one of the study pingos. The geophysical investigations were undertaken, along with core sampling and permafrost drilling, to enable measurement of the ground temperature regime. Drilling (ground truthing) results support field geophysical investigations, and have led to the development of a technique for distinguishing massive ice and overburden material of the permafrost. The two‐dimensional DC resistivity sounding tomography and ground‐penetrating radar profiling are useful for ice detection under heterogeneous conditions. However, the DC resistivity sounding investigation required high‐quality ground contact and less area coverage. The active layer thickness and the homogeneous horizontal structure of the overburden material are important parameters influencing detection of massive ice in permafrost for most methods such as seismic, TEM, or surface NMR.

Young (late Amazonian), near-surface, ground ice features near the equator, Athabasca Valles, Mars

A suite of four feature types in a ∼20 km 2 area near 10° N, 204° W in Athabasca Valles is interpreted to have resulted from near-surface ground ice. These features include mounds, conical forms with rimmed summit depressions, flatter irregularly-shaped forms with raised rims, and polygonal terrain. Based on morphology, size, and analogy to terrestrial ground ice forms, these Athabascan features are interpreted as pingos, collapsing pingos, pingo scars, and thermal contraction polygons, respectively. Thermal Infrared Mapping Spectrometer (THEMIS) data and geological features in the area are consistent with a sedimentary substrate underlying these features. These observations lead us to favor a ground ice interpretation, although we do not rule out volcanic and especially glaciofluvial hypotheses. The hypothesized ground ice that formed the mounds and rimmed features may have been emplaced via the deposition of saturated sediment during flooding; an alternative scenario invokes magmatically cycled groundwater. The ground ice implicit in the hypothesized thermal contraction polygons may have derived either from this flooding/ground water, or from atmospheric water vapor. The lack of obvious flood modification of the mounds and rimmed features indicates that they formed after the most recent flood inundated the area. Analogy with terrestrial pingos suggests that ground ice may be still extant within the positive relief mounds. As the water that flooded down Athabasca Valles emerged via a volcanotectonic fissure from a deep aquifer, any extant pingo ice may contain evidence of a deep subsurface biosphere.

Ground penetrating radar investigations of open system pingos, Adventdalen, Svalbard

Ground penetrating radar (GPR) investigations conducted on two open system pingos, Innerhytte pingo and Riverbed pingo, in Adventdalen, Svalbard, are described. The surveys were undertaken at frequencies of 50 and 100 Mhz, and are used in an interpretation of the internal structure, origins and evolution of these landforms. Surface exposures suggest that both pingos are largely formed in weak Jurassic shales. Little evidence for the presence of large bodies of massive ice was found. Strong subsurface reflections within the core of both pingos are interpreted as representing either the presence of alternating shale and ice units, or variations in the chemistry, ice crystal properties or air content of pingo ice. Steeply dipping reflections are most pronounced on the flanks of the pingos and are orientated sub-parallel to the pingo surface. Variability in the depth of signal penetration is attributed to variability in subsurface properties, particularly ice content, and the attenuation of the signal by fine grained shales. The internal structure of Innerhytte pingo indicates that the point of sub-pingo groundwater injection has migrated southwards. Lack of evidence for ground ice beneath the north-eastern zone of this landform suggests that at least part of the landform is an erosional remnant of bedrock caused by fluvial incision of Janssonhaugen, with pingo development occurring only in the area proximal to the upper apex of the feature. Both Innerhytte and Riverbed are characterized by conspicuous surface icings, with groundwater flow to the surface in late winter, prior to initiation of active-layer thawing, suggesting derivation from a deep groundwater source.

Electrical freezing potentials measured in a pingo growing in the western Canadian Arctic

A probe containing copper electrodes, thermocouples, and a soil salinity sensor assembly with calibrated thermistors, was installed in a vertical drill hole at the top of a pingo located about 20 km southwest of Tuktoyaktuk, Northwest Territories. The electrodes were positioned both in the pingo ice at the top and in the underlying water lens. The salinity sensors were in the water lens. Measurements of electrical potentials developed on different electrodes in succeeding years after installation showed a sharp decrease in the potential at the electrode located at or near the freezing interface between the ice and water, when compared to that developed on the other electrodes. The magnitude of the freezing potentials measured were in the range of −50 to −100 mV (in one year up to 174 mV). The present field experiment showed that electrical potential probes can detect the progress of the freezing front between ice and water under natural conditions when the freezing rate is extremely slow. The average rate of advancement of the freezing front between the ice and water lens within the pingo was 15 cm per year.

Seasonal growth bands in pingo ice

Field studies of pingo ice show that alternating clear and bubble bands may grow when water freezes at the top of a subpingo water lens. A study of the banding at one excellent exposure of pingo ice shows that the clear bands probably grew during propagation of the cold winter temperature waves, the bubble bands, from the warmer summer temperature waves. The likely cause for the gradual transitions from clear to bubble bands followed by the abrupt transitions from bubble to clear bands was marked asymmetry of the periodic temperature waves in permafrost overlain by an active layer whose thermal properties varied seasonally. Pingo growth, as determined from the growth of bands, shows good agreement with Stefan's equation where growth varied as the square root of time. Geochemical profiles show no systematic change with depth. Stable-isotope profiles for δ18O and δD show linear trends with depth and a depletion of the heavy isotopes. The co-isotope slope of 7.2 suggests freezing, with the input being impoverished in the heavy isotopes.

Pingo ice of the western Arctic coast, Canada

A field study of pingo ice exposures shows that all pingos contain pore ice and varying proportions of intrusive ice, segregated ice, dilation crack ice, and ice wedge ice. The intrusive ice is derived from water in a subpingo water lens. The ice is usually pure and columnar grained with c axes normal to the direction of heat flow. The columnar grains tend to develop parallel lines normal to the c axis upon exposure to radiation. Precise surveys of pingo growth for the 1973–1983 period show that displacement vectors are upward and radially outward and that radial dilation cracks are produced by circumferential stretching. The dilation cracks, which can open at any time of the year, become infilled with surface water and also with soil from the pingo overburden. The cumulative width of the dilation crack ice approximates the stretch of the pingo overburden as it is domed by pingo growth. Dilation crack ice is vertically banded. The bands are much wider than those in ice wedge ice and have less vertical taper to them. Segregated ice, under high subpermafrost pore-water pressures, may grow in medium-grained sands. Calculations based upon the 1973–1983 growth of one pingo with an intrusive ice core show that the annual increment of intrusive ice is greatly exceeded by pore ice and segregation ice, an observation probably true for many pingos.

A first approximation of the volume of ground ice, Richards Island, Pleistocene Mackenzie delta, Northwest Territories, Canada

Using data contained in the Mackenzie Valley Geotechnical Data Bank together with data derived from morphometric analyses of topographic maps and air photographs, the volume of ground ice present in the upper 10 m of Richards Island is calculated to be 10.27 km3. Pore and segregated ice constitute over 80% of the total ice volume. Wedge ice constitutes between 12 and 16% of total ice volume in the upper 4.5 m, and approximately 36% of all excess ice. In the upper 1–2 m, wedge ice may exceed 50% of earth materials. Pingo ice is insignificant in terms of its contribution to total ice volumes. Excess ice constitutes 14% of the upper 10 m of permafrost; it follows that thawing of this layer of permafrost may lead to an average subsidence of 1.4 m.The results of this study are probably typical of other areas of the Pleistocene Mackenzie delta. There is also general agreement with data obtained from arctic Alaska.

Fabrics of Icing-Mound and Pingo Ice in Permafrost

Abstract Crystallization histories of some ice layers in permafrost are inferred from crystal size, shape, dimensional and lattice orientation, and inclusion patterns. In an icing mound, formed by injection of water beneath frozen active-layer soil, early growth was rapid, indicated by copious small crystals and bubbles, followed by slower growth giving rise to crystals and bubbles elongate parallel to the freezing direction, c-axes were normal to crystal long axes. In a small pingo, bulk water existed temporarily at the freezing interface and freezing was unidirectional. In a larger pingo, variations in freezing rate were inferred. Later flow of ice modifies growth fabrics.

Fabrics of Icing-Mound and Pingo Ice in Permafrost

AbstractCrystallization histories of some ice layers in permafrost are inferred from crystal size, shape, dimensional and lattice orientation, and inclusion patterns. In an icing mound, formed by injection of water beneath frozen active-layer soil, early growth was rapid, indicated by copious small crystals and bubbles, followed by slower growth giving rise to crystals and bubbles elongate parallel to the freezing direction, c-axes were normal to crystal long axes. In a small pingo, bulk water existed temporarily at the freezing interface and freezing was unidirectional. In a larger pingo, variations in freezing rate were inferred. Later flow of ice modifies growth fabrics.

Geographical zonality of frozen ground formation

Abstract The zonal pattern of frozen ground formation (cryolithogenesis) in northern Eurasia derives from a complex set of factors, including latitude, continentality, crustal movements, lithology and the historical movement of natural zones during the Pleistocene and Holocene. The author defines a zonal pattern by limiting himself to the varying characteristics of three typical genetic layers in superimposed (cryoepigenetic) frozen ground consisting of unconsolidated sediment. The three layers (from top to bottom) are distinguished by (a) frost weathering (cryoeluvial processes); (b) by active frost metamorphism (cryodiagenetic processes); (c) by passive frost metamorphism. The products of frost weathering in the surface layer are loesslike mantle loams; active metamorphism is associated with polygonal wedge ice, pingo ice and finally textured segregated soil ice; passive metamorphism is associated with sill‐like sheet ice and coarsely textured pore ice. Mean annual temperature and winter temperature gra...