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Field and theory : lectures in geocryology = Terrain et thâeorie : essais de gâeocryologie
Contains 10 papers resulting from a lecture series held in honour of Dr. J. Ross Mackay at the University of British Columbia during 1980-81. Papers delineate the challenge of field work in the harsh periglacial environment and the resulting difficulty in testing theory in the field with rigour. Topics covered include soil freezing, ice formation and thaw.
Book
Ground Ice and Landforms of the Yenisei Gulf Coastal Plains and Adjacent Parts of the Byrranga Mountains
AbstractThe Yenisei Gulf is located in Arctic Russia in the area of continuous low-temperature permafrost. Cryogenic processes in this region created a unique set of geomorphic features characteristic of the permafrost landscape. Large deposits of ground ice are important features of the Quaternary sediment exposures along the coasts of the Yenisei Gulf. Tabular Massive Ground Ice (TMGI) and Ground Ice Wedges (GIW) are unique natural formations that are common in the area. The TMGI thickness can reach up to 50 m and have a length of hundreds of meters. The GIW can be 12 m deep with upper parts that are 3 m thick. Ground ice is commonly located close to the surface. The presence of bodies of various types of ground ice and ice-rich sediments makes permafrost in the region extremely vulnerable to warming climate or changing surface conditions, such as snow redistribution, vegetation change and human disturbances. Melting of ground ice leads to the development of thermokarst and erosion. Giant thermal cirques, gullies and landslides are developing on slopes, while thermokarst lakes are formed on flat topographic surfaces on ice-rich permafrost. The article discusses the role of ground ice and cryogenic processes in the development of the modern relief in the northern part of Russia.
Journal Article
Massive ground ice of glacial meltwater origin in raised marine-deltaic sediments, Fosheim Peninsula, high Arctic Canada
In the Canadian high Arctic, tabular massive ground ice is found extensively throughout the Eureka Sound Lowlands (ESL). This study evaluates the development of tabular massive ice in raised marine-deltaic sediments of the ESL based on new cryostratigraphic data from sites found between the coastline and the Holocene marine limit. At all sites, massive ice is found below laminated fine-grained marine sediments, and the upper contact between the ice and the overlying marine sediments is conformable and gradational. The concentration of major ions in the massive ice is orders of magnitude higher than expected for glacial ice, but Na/Cl molar ratios vary following elevation: the higher-elevation site has ratios similar to glacial ice, but sites at lower elevations have ratios closer to seawater. The δ18O values of the ice indicate that the main source of water is glacial meltwater but the δD-δ18O regression slope values suggest that the ice formed in an open system while receiving an influx that had a substantially different isotopic signature than the initial reservoir. The development of massive ice in the marine-deltaic sediments involves glacial meltwater recharging an aquifer beneath the Holocene marine sediments with a contribution of 1–10% of seawater.
Journal Article
20-year permafrost evolution documented through petrophysical joint inversion, thermal and soil moisture data
This study investigates the ground characteristics of the high altitude (3410 m a.s.l.) permafrost site Stockhorn in the Swiss Alps using a combination of surface and subsurface temperature, soil moisture, electrical resistivity and P-wave velocity time series data including a novel approach to explicitly quantify changes in ground ice content. This study was motivated by the clear signal of permafrost degradation visible in the full dataset at this long-term monitoring site within the PERMOS (Permafrost Monitoring Switzerland) network. Firstly, we assess the spatio-temporal evolution of the ground ice and water content by a combined analysis of all available in situ thermal (borehole and ground surface temperature), hydrological (soil moisture) and geophysical (geoelectric and seismic refraction) data over two decades (2002–2022) regarding the driving factors for the spatially different warming. Secondly, we explicitly quantify the volumetric water and ice content and their changes in the subsurface from 2015 to 2022 using a time-consistent petrophysical joint inversion scheme within the open-source library pyGIMLi. The petrophysical joint inversion scheme has been improved by constraining the rock content to be constant in time for six subsequent inversions to obtain consistent changes in ice and water content over the monitoring period based on jointly inverted resistivity and traveltime data. All different data show a warming trend of the permafrost. The ice content modeled from the petrophysical joint inversion has decreased by about 15 vol.% between 2015 and 2022. Changes in ice content are first observed in the lower, south-facing part of the profile. As a result, resistivity and P-wave velocity have been decreasing significantly. Permafrost temperatures measured in the boreholes have increased between 0.5 °C and 1 °C in 20 years. Our study shows the high value of joint and quantitative analysis of datasets comprising complementary subsurface variables for long-term permafrost monitoring.
Journal Article
Yamal Peninsula, Permafrost-related Terrain Phenomena: Tabular Ground Ice, Thermocirques and Gas Emission Craters
AbstractLeading controls of terrain development in the permafrost zone are various types of ground ice. The paper deals with the formation of specific landforms in the continuous permafrost of Yamal Peninsula with tabular ground ice in the geological section. Processes related to tabular ground ice (TGI, thick and extended ground-ice layers) thaw are triggered by climate warming. Air temperature rise in most environments results in higher ground temperature and deeper active layer (the layer in the upper part of permafrost, which thaws in summer and freezes back in winter). Warming of the last decades had caused an increase in the rate of thaw reaching the upper surface of TGI and starting thermodenudation. Climate warming may also lead to increase in ground temperature, which triggers gas-emission crater formation through decomposition of methane clathrates up to formation of high pressure under the TGI layer until it breaks. Thus, TGI serves as a source of water for saturation of slope deposits and a shear surface for movement of these deposits down slope under the action of both heat and gravity. The role of TGI in the process of gas emission crater formation is not related to its melting as in thermodenudation, but serves as an impermeable to gas, plastic layer. Gas released from decomposition of methane clathrates accumulates beneath the ice layer deforming it to form a gas-inflated mound—predecessor of the crater. Thermocirques, resulting from thermodenudation, and gas emission craters evolve with time depending on the ice extent and warming trend.
Journal Article
Recognition and Classification of Martian Chaos Terrains Using Imagery Machine Learning: A Global Distribution of Chaos Linked to Groundwater Circulation, Catastrophic Flooding, and Magmatism on Mars
Martian chaos terrains are fractured depressions consisting of block landforms that are often located in source areas of outflow channels. Numerous chaos and chaos-like features have been found on Mars; however, a global-scale classification has not been pursued. Here, we perform recognition and classification of Martian chaos using imagery machine learning. We developed neural network models to classify block landforms commonly found in chaos terrains—which are associated with outflow channels formed by water activity (referred to as Aromatum-Hydraotes-Oxia-like (or AHO) chaos blocks) or with geological features suggesting volcanic activity (Arsinoes-Pyrrhae-like (or AP) chaos blocks)—and also non-chaos surface features, based on >1400 surface images. Our models can recognize chaos and non-chaos features with 93.9% ± 0.3% test accuracy, and they can be used to classify both AHO and AP chaos blocks with >89 ± 4% test accuracy. By applying our models to ~3150 images of block landforms of chaos-like features, we identified 2 types of chaos terrain. These include hybrid chaos terrain, where AHO and AP chaos blocks co-exist in one basin, and AHO-dominant chaos terrain. Hybrid chaos terrains are predominantly found in the circum-Chryse outflow channels region. AHO-dominant chaos terrains are widely distributed across Aeolis, Cydonia, and Nepenthes Mensae along the dichotomy boundary. Their locations coincide with regions suggested to exhibit upwelling groundwater on Hesperian Mars.
Journal Article
Coastal Retreat Due to Thermodenudation on the Yugorsky Peninsula, Russia during the Last Decade, Update since 2001–2010
Thermodenudation on the Kara seacoast, the Yugorsky Peninsula, Russia, is studied by analyzing remote-sensing data. Landforms resulting from the thaw of tabular ground ice, referred to as thermocirques, are formed due to polycyclic retrogressive thaw slumps, during the last decade 2010–2020. We calculate the retreat rate of the thermocirque edge using various statistical approaches. We compared thermocirque outlines by the end of each time interval defined by the dates of available very-high-resolution imagery. Six thermocirques within two key sites on the Yugorsky peninsula are monitored. We correlate each of the thermocirque edge’s retreat rates to various climatic parameters obtained at the Amderma weather station to understand the interrelation patterns better. As a result, we find a very low correlation between the retreat rate of each thermocirque and summer warmth, rainfall, and wave action. In general, the activity of thermodenudation decreases in time from the previous decade (2001–2010) to 2010–2020, and from 2010 towards 2020, although the summer warmth trend increases dramatically. A single thermocirque or series of thermocirques expand in response to environmental and geological factors in coastal retreat caused by thermodenudation.
Journal Article
Three-Dimensional Numerical Modeling of Ground Ice Ablation in a Retrogressive Thaw Slump and Its Hydrological Ecosystem Response on the Qinghai-Tibet Plateau, China
Retrogressive thaw slumps (RTSs), which frequently occur in permafrost regions of the Qinghai-Tibet Plateau (QTP), China, can cause significant damage to the local surface, resulting in material losses and posing a threat to infrastructure and ecosystems in the region. However, quantitative assessment of ground ice ablation and hydrological ecosystem response was limited due to a lack of understanding of the complex hydro-thermal process during RTS development. In this study, we developed a three-dimensional hydro-thermal coupled numerical model of a RTS in the permafrost terrain at the Beilu River Basin of the QTP, including ice–water phase transitions, heat exchange, mass transport, and the parameterized exchange of heat between the active layer and air. Based on the calibrated hydro-thermal model and combined with the electrical resistivity tomography survey and sample analysis results, a method for estimating the melting of ground ice was proposed. Simulation results indicate that the model effectively reflects the factual hydro-thermal regime of the RTS and can evaluate the ground ice ablation and total suspended sediment variation, represented by turbidity. Between 2011 and 2021, the maximum simulated ground ice ablation was in 2016 within the slump region, amounting to a total of 492 m3, and it induced the reciprocal evolution, especially in the headwall of the RTS. High ponding depression water turbidity values of 28 and 49 occurred in the thawing season in 2021. The simulated ground ice ablation and turbidity events were highly correlated with climatic warming and wetting. The results offer a valuable approach to assessing the effects of RTS on infrastructure and the environment, especially in the context of a changing climate.
Journal Article
Reindeer turning maritime: Ice‐locked tundra triggers changes in dietary niche utilization
The rapid warming of the Arctic may not only alter species’ abundances and distributions, but likely also the trophic interactions within and between ecosystems. On the high‐arctic tundra, extreme warm spells and associated rain‐on‐snow events in winter can encapsulate the vegetation entirely in ground‐ice (i.e., basal ice) and directly or indirectly affect plants, herbivores, and carnivores. However, the implications of such extreme events for trophic interactions and food‐web ecology are generally far from understood. Here, we show that wild Svalbard reindeer populations increasingly isolated by lack of sea‐ice respond to rain‐on‐snow and ice‐locked pastures by increased kelp consumption. Based on annual population surveys in late winters 2006–2015, the proportion of individual reindeer feeding along the shoreline increased the icier the winter. Stable isotope values (δ34S, δ13C, δ15N) of plants, washed‐ashore kelp, and fresh reindeer feces collected along coast‐inland gradients, confirmed ingestion of marine biomass by the reindeer in the shoreline habitat. Thus, even on remote islands and peninsulas increasingly isolated by sea‐ice loss, effects of climate change may be buffered in part by behavioral plasticity and increased use of resource subsidies. This marine dimension of a terrestrial herbivore's realized foraging niche adds to evidence that global warming significantly alters trophic interactions as well as meta‐ecosystem processes.
Journal Article
An Estimation of Ground Ice Volumes in Permafrost Layers in Northeastern Qinghai-Tibet Plateau, China
The ground ice content in permafrost serves as one of the dominant properties of permafrost for the study of global climate change, ecology, hydrology and engineering construction in cold regions. This paper initially attempts to assess the ground ice volume in permafrost layers on the Qinghai-Tibet Plateau by considering landform types, the corresponding lithological composition, and the measured water content in various regions. An approximation demonstrating the existence of many similarities in lithological composition and water content within a unified landform was established during the calculations. Considerable knowledge of the case study area, here called the Source Area of the Yellow(Huanghe) River(SAYR) in the northeastern Qinghai-Tibet Plateau, has been accumulated related to permafrost and fresh water resources during the past 40 years. Considering the permafrost distribution, extent, spatial distribution of landform types, the ground ice volume at the depths of 3.0–10.0 m below the ground surface was estimated based on the data of 101 boreholes from field observations and geological surveys in different types of landforms in the permafrost region of the SAYR. The total ground ice volume in permafrost layers at the depths of 3.0–10.0 m was approximately(51.68 ± 18.81) km~3, and the ground ice volume per unit volume was(0.31 ± 0.11) m~3/m~3. In the horizontal direction, the ground ice content was higher in the landforms of lacustrine-marshland plains and alluvial-lacustrine plains, and the lower ground ice content was distributed in the erosional platforms and alluvial-proluvial plains. In the vertical direction, the volume of ground ice was relatively high in the top layers(especially near the permafrost table) and at the depths of 7.0–8.0 m. This calculation method will be used in the other areas when the necessary information is available, including landform type, borehole data, and measured water content.
Journal Article