For remote communities in the discontinuous permafrost zone, access to permafrost distribution maps for hazard assessment is limited and more general products are often inadequate for use in local‐scale planning. In this study we apply established analytical methods to illustrate a time‐ and cost‐efficient method for conducting community‐scale permafrost mapping in the community of Whatì, Northwest Territories, Canada. We ran a binary logistic regression (BLR) using a combination of field data, digital surface model‐derived variables, and remotely sensed products. Independent variables included vegetation, topographic position index, and elevation bands. The dependent variable was sourced from 139 physical checks of near‐surface permafrost presence/absence sampled across the variable boreal–wetland environment. Vegetation is the strongest predictor of near‐surface permafrost in the regression. The regression predicts that 50.0% (minimum confidence: 36%) of the vegetated area is underlain by near‐surface permafrost with a spatial accuracy of 72.8%. Analysis of data recorded across various burnt and not‐burnt environments indicated that recent burn scenarios have significantly influenced the distribution of near‐surface permafrost in the community. A spatial burn analysis predicted up to an 18.3% reduction in near‐surface permafrost coverage, in a maximum burn scenario without factoring in the influence of climate change. The study highlights the potential that in an ecosystem with virtually homogeneous air temperature, ecosystem structure and disturbance history drive short‐term changes in permafrost distribution and evolution. Thus, at the community level these factors should be considered as seriously as changes to air temperature as climate changes.
{"title":"Influence of ecosystem and disturbance on near‐surface permafrost distribution, Whatì, Northwest Territories, Canada","authors":"Seamus V. Daly, P. Bonnaventure, W. Kochtitzky","doi":"10.1002/ppp.2160","DOIUrl":"https://doi.org/10.1002/ppp.2160","url":null,"abstract":"For remote communities in the discontinuous permafrost zone, access to permafrost distribution maps for hazard assessment is limited and more general products are often inadequate for use in local‐scale planning. In this study we apply established analytical methods to illustrate a time‐ and cost‐efficient method for conducting community‐scale permafrost mapping in the community of Whatì, Northwest Territories, Canada. We ran a binary logistic regression (BLR) using a combination of field data, digital surface model‐derived variables, and remotely sensed products. Independent variables included vegetation, topographic position index, and elevation bands. The dependent variable was sourced from 139 physical checks of near‐surface permafrost presence/absence sampled across the variable boreal–wetland environment. Vegetation is the strongest predictor of near‐surface permafrost in the regression. The regression predicts that 50.0% (minimum confidence: 36%) of the vegetated area is underlain by near‐surface permafrost with a spatial accuracy of 72.8%. Analysis of data recorded across various burnt and not‐burnt environments indicated that recent burn scenarios have significantly influenced the distribution of near‐surface permafrost in the community. A spatial burn analysis predicted up to an 18.3% reduction in near‐surface permafrost coverage, in a maximum burn scenario without factoring in the influence of climate change. The study highlights the potential that in an ecosystem with virtually homogeneous air temperature, ecosystem structure and disturbance history drive short‐term changes in permafrost distribution and evolution. Thus, at the community level these factors should be considered as seriously as changes to air temperature as climate changes.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2022-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50931898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Arthur Monhonval, J. Strauss, M. Thomas, C. Hirst, H. Titeux, Justine Louis, Alexia Gilliot, Eléonore du Bois d'Aische, B. Pereira, Aubry Vandeuren, G. Grosse, Lutz Schirrmeister, L. Jongejans, M. Ulrich, S. Opfergelt
The stabilizing properties of mineral–organic carbon (OC) interactions have been studied in many soil environments (temperate soils, podzol lateritic soils, and paddy soils). Recently, interest in their role in permafrost regions is increasing as permafrost was identified as a hotspot of change. In thawing ice‐rich permafrost regions, such as the Yedoma domain, 327–466 Gt of frozen OC is buried in deep sediments. Interactions between minerals and OC are important because OC is located very near the mineral matrix. Mineral surfaces and elements could mitigate recent and future greenhouse gas emissions through physical and/or physicochemical protection of OC. The dynamic changes in redox and pH conditions associated with thermokarst lake formation and drainage trigger metal‐oxide dissolution and precipitation, likely influencing OC stabilization and microbial mineralization. However, the influence of thermokarst processes on mineral–OC interactions remains poorly constrained. In this study, we aim to characterize Fe, Mn, Al, and Ca minerals and their potential protective role for OC. Total and selective extractions were used to assess the crystalline and amorphous oxides or complexed metal pools as well as the organic acids found within these pools. We analyzed four sediment cores from an ice‐rich permafrost area in Central Yakutia, which were drilled (i) in undisturbed Yedoma uplands, (ii) beneath a recent lake formed within Yedoma deposits, (iii) in a drained thermokarst lake basin, and (iv) beneath a mature thermokarst lake from the early Holocene period. We find a decrease in the amount of reactive Fe, Mn, Al, and Ca in the deposits on lake formation (promoting reduction reactions), and this was largely balanced by an increase in the amount of reactive metals in the deposits on lake drainage (promoting oxidation reactions). We demonstrate an increase in the metal to C molar ratio on thermokarst process, which may indicate an increase in metal–C bindings and could provide a higher protective role against microbial mineralization of organic matter. Finally, we find that an increase in mineral–OC interactions corresponded to a decrease in CO2 and CH4 gas emissions on thermokarst process. Mineral–OC interactions could mitigate greenhouse gas production from permafrost thaw as soon as lake drainage occurs.
{"title":"Thermokarst processes increase the supply of stabilizing surfaces and elements (Fe, Mn, Al, and Ca) for mineral–organic carbon interactions","authors":"Arthur Monhonval, J. Strauss, M. Thomas, C. Hirst, H. Titeux, Justine Louis, Alexia Gilliot, Eléonore du Bois d'Aische, B. Pereira, Aubry Vandeuren, G. Grosse, Lutz Schirrmeister, L. Jongejans, M. Ulrich, S. Opfergelt","doi":"10.1002/ppp.2162","DOIUrl":"https://doi.org/10.1002/ppp.2162","url":null,"abstract":"The stabilizing properties of mineral–organic carbon (OC) interactions have been studied in many soil environments (temperate soils, podzol lateritic soils, and paddy soils). Recently, interest in their role in permafrost regions is increasing as permafrost was identified as a hotspot of change. In thawing ice‐rich permafrost regions, such as the Yedoma domain, 327–466 Gt of frozen OC is buried in deep sediments. Interactions between minerals and OC are important because OC is located very near the mineral matrix. Mineral surfaces and elements could mitigate recent and future greenhouse gas emissions through physical and/or physicochemical protection of OC. The dynamic changes in redox and pH conditions associated with thermokarst lake formation and drainage trigger metal‐oxide dissolution and precipitation, likely influencing OC stabilization and microbial mineralization. However, the influence of thermokarst processes on mineral–OC interactions remains poorly constrained. In this study, we aim to characterize Fe, Mn, Al, and Ca minerals and their potential protective role for OC. Total and selective extractions were used to assess the crystalline and amorphous oxides or complexed metal pools as well as the organic acids found within these pools. We analyzed four sediment cores from an ice‐rich permafrost area in Central Yakutia, which were drilled (i) in undisturbed Yedoma uplands, (ii) beneath a recent lake formed within Yedoma deposits, (iii) in a drained thermokarst lake basin, and (iv) beneath a mature thermokarst lake from the early Holocene period. We find a decrease in the amount of reactive Fe, Mn, Al, and Ca in the deposits on lake formation (promoting reduction reactions), and this was largely balanced by an increase in the amount of reactive metals in the deposits on lake drainage (promoting oxidation reactions). We demonstrate an increase in the metal to C molar ratio on thermokarst process, which may indicate an increase in metal–C bindings and could provide a higher protective role against microbial mineralization of organic matter. Finally, we find that an increase in mineral–OC interactions corresponded to a decrease in CO2 and CH4 gas emissions on thermokarst process. Mineral–OC interactions could mitigate greenhouse gas production from permafrost thaw as soon as lake drainage occurs.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2022-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43313668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Glaciers and frozen‐debris landforms have coexisted and episodically or continuously interacted throughout the Holocene at elevations where the climate conditions are cold enough for permafrost to occur. In the European Alps, the Little Ice Age (LIA) characterized the apogee of the last interaction phase. In areas of consecutive post‐LIA glacier shrinkage, the geomorphological dominant conditioning of the ongoing paraglacial phase may have transitioned from glacial to periglacial and later even shifted to post‐periglacial. Such transitions can be observed through the morphodynamics of glacitectonized frozen landforms (GFLs), which are permafrost‐related pre‐existing frozen masses of debris deformed (tectonized) by the pressure exerted by an interacting glacier. This contribution aims at evidencing the processes driving the ongoing morphodynamical evolution of an actively back‐creeping GFL within the LIA forefield of the Aget glacier on the basis of long‐term time series of ground surface temperature, and in‐situ geodetic and geoelectrical measurements. Our observations for the last two decades (1998–2020), which have been the warmest since the LIA, reveal a resistivity decrease in the permafrost body and a surface subsidence of up to a few centimeters per year. The former indicate a liquid water‐to‐ice content ratio increase within the permafrost body and the latter a ground ice melt at the permafrost table, both processes having taken place heterogeneously at the scale of the landform. The absence of acceleration of landform motion during that period despite a probable warming trend of the frozen ground may indicate that the ongoing degradation is reaching a tipping point at which processes related to interparticle friction and thinning of the permafrost body contribute to gradually inactivate the mechanism of permafrost creep.
{"title":"Post‐glacial dynamics of an alpine Little Ice Age glacitectonized frozen landform (Aget, western Swiss Alps)","authors":"Julie Wee, R. Delaloye","doi":"10.1002/ppp.2158","DOIUrl":"https://doi.org/10.1002/ppp.2158","url":null,"abstract":"Glaciers and frozen‐debris landforms have coexisted and episodically or continuously interacted throughout the Holocene at elevations where the climate conditions are cold enough for permafrost to occur. In the European Alps, the Little Ice Age (LIA) characterized the apogee of the last interaction phase. In areas of consecutive post‐LIA glacier shrinkage, the geomorphological dominant conditioning of the ongoing paraglacial phase may have transitioned from glacial to periglacial and later even shifted to post‐periglacial. Such transitions can be observed through the morphodynamics of glacitectonized frozen landforms (GFLs), which are permafrost‐related pre‐existing frozen masses of debris deformed (tectonized) by the pressure exerted by an interacting glacier. This contribution aims at evidencing the processes driving the ongoing morphodynamical evolution of an actively back‐creeping GFL within the LIA forefield of the Aget glacier on the basis of long‐term time series of ground surface temperature, and in‐situ geodetic and geoelectrical measurements. Our observations for the last two decades (1998–2020), which have been the warmest since the LIA, reveal a resistivity decrease in the permafrost body and a surface subsidence of up to a few centimeters per year. The former indicate a liquid water‐to‐ice content ratio increase within the permafrost body and the latter a ground ice melt at the permafrost table, both processes having taken place heterogeneously at the scale of the landform. The absence of acceleration of landform motion during that period despite a probable warming trend of the frozen ground may indicate that the ongoing degradation is reaching a tipping point at which processes related to interparticle friction and thinning of the permafrost body contribute to gradually inactivate the mechanism of permafrost creep.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2022-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44964966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaoying Li, H. Jin, Long Sun, Hongwei Wang, Yadong Huang, R. He, X. Chang, Shao-peng Yu, S. Zang
Northeast China has experienced rapid and substantial climate warming over the past 60 years, and permafrost is degrading rapidly. In this study, permafrost distribution and extent in Northeast China were estimated from monitored ground surface temperatures using the temperature at the top of permafrost (TTOP) model and geographically weighted regression method. Using the TTOP model, the computed mean annual ground temperatures (MAGT@TOP) at the top of permafrost of Northeast China increased significantly from 1961–1990 (1.8°C) to 1991–2020 (3.0°C). The areal extents of permafrost defined by a subzero MAGT@TOP (MAGT@TOP ≤ 0°C) in Northeast China in the period 1961–1990 and 1991–2020 were estimated at 461.5 × 103 and 365.8 × 103 km2, respectively, indicating a decline of 95.7 × 103 km2. On average, the simulated MAGT@TOP values were 2.07°C lower than the observed MAGT@TOP values in boreholes. The linear correlation coefficient between the simulated and measured MAGT@TOP values was 0.63. Compared with the simulation results of other previous models, the result of this research is more reliable and accurate. The compiled maps of permafrost distribution can serve as an important reference for the study of permafrost changes in Northeast China.
{"title":"TTOP‐model‐based maps of permafrost distribution in Northeast China for 1961–2020","authors":"Xiaoying Li, H. Jin, Long Sun, Hongwei Wang, Yadong Huang, R. He, X. Chang, Shao-peng Yu, S. Zang","doi":"10.1002/ppp.2157","DOIUrl":"https://doi.org/10.1002/ppp.2157","url":null,"abstract":"Northeast China has experienced rapid and substantial climate warming over the past 60 years, and permafrost is degrading rapidly. In this study, permafrost distribution and extent in Northeast China were estimated from monitored ground surface temperatures using the temperature at the top of permafrost (TTOP) model and geographically weighted regression method. Using the TTOP model, the computed mean annual ground temperatures (MAGT@TOP) at the top of permafrost of Northeast China increased significantly from 1961–1990 (1.8°C) to 1991–2020 (3.0°C). The areal extents of permafrost defined by a subzero MAGT@TOP (MAGT@TOP ≤ 0°C) in Northeast China in the period 1961–1990 and 1991–2020 were estimated at 461.5 × 103 and 365.8 × 103 km2, respectively, indicating a decline of 95.7 × 103 km2. On average, the simulated MAGT@TOP values were 2.07°C lower than the observed MAGT@TOP values in boreholes. The linear correlation coefficient between the simulated and measured MAGT@TOP values was 0.63. Compared with the simulation results of other previous models, the result of this research is more reliable and accurate. The compiled maps of permafrost distribution can serve as an important reference for the study of permafrost changes in Northeast China.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2022-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44542913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Issue Information","authors":"","doi":"10.1002/ppp.2120","DOIUrl":"https://doi.org/10.1002/ppp.2120","url":null,"abstract":"No abstract is available for this article.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46313248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
General geomorphometry is concerned with the geometric form of the continuous land surface and can be useful for identifying topographic “signatures.” Hypsometry has found numerous applications in several subfields of geomorphology, but has not been used extensively in published periglacial work. Hypsometric analysis was applied in this study to several unglaciated and glaciated locales in Alaska's Yukon‐Tanana Upland and Indian River Upland physiographic sections, extensive areas of eastern Beringia in which cryoplanation landforms are ubiquitous. Never‐glaciated terrain in this region has a hypsometric signature distinctly different from that of glaciated areas within sample areas ranging in size from 0.25 to 100 km2. Cryoplanated terrain exhibits a distinctive convex‐upward hypsometric signature, a reflection of a greater proportion of the reference solid (land mass) remaining intact than in typical mature fluvial or glaciated terrain. Because the elevational position of cryoplanation terraces is slightly below and parallel with snowline position it is, in effect, climatically determined from above, and localized planar surfaces develop near that level. Comparison with terrain in the southwestern USA demonstrates that substantial differences also exist between the hypsometry of upland periglacial terrain in eastern Beringia and that of inselbergs and pediments in warm‐desert geomorphic landscapes, casting doubt on a suggestion that cryoplanation terraces and cryopediments in high‐latitude mountains could be inherited from past intervals of subtropical desert conditions We conclude that characteristic periglacial erosional topography exists in unglaciated areas of Beringia and can be detected and described quantitatively through objective methods.
{"title":"Characteristic periglacial topography: Multi‐scale hypsometric analysis of cryoplanated uplands in eastern Beringia","authors":"C. Queen, F. Nelson","doi":"10.1002/ppp.2148","DOIUrl":"https://doi.org/10.1002/ppp.2148","url":null,"abstract":"General geomorphometry is concerned with the geometric form of the continuous land surface and can be useful for identifying topographic “signatures.” Hypsometry has found numerous applications in several subfields of geomorphology, but has not been used extensively in published periglacial work. Hypsometric analysis was applied in this study to several unglaciated and glaciated locales in Alaska's Yukon‐Tanana Upland and Indian River Upland physiographic sections, extensive areas of eastern Beringia in which cryoplanation landforms are ubiquitous. Never‐glaciated terrain in this region has a hypsometric signature distinctly different from that of glaciated areas within sample areas ranging in size from 0.25 to 100 km2. Cryoplanated terrain exhibits a distinctive convex‐upward hypsometric signature, a reflection of a greater proportion of the reference solid (land mass) remaining intact than in typical mature fluvial or glaciated terrain. Because the elevational position of cryoplanation terraces is slightly below and parallel with snowline position it is, in effect, climatically determined from above, and localized planar surfaces develop near that level. Comparison with terrain in the southwestern USA demonstrates that substantial differences also exist between the hypsometry of upland periglacial terrain in eastern Beringia and that of inselbergs and pediments in warm‐desert geomorphic landscapes, casting doubt on a suggestion that cryoplanation terraces and cryopediments in high‐latitude mountains could be inherited from past intervals of subtropical desert conditions We conclude that characteristic periglacial erosional topography exists in unglaciated areas of Beringia and can be detected and described quantitatively through objective methods.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2022-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43212740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The longest time series of surface velocities recorded on a rock glacier in the French Alps, covering more than three decades, has been recorded since 1983 on the Laurichard rock glacier (Ecrins range). The time signal of velocity changes is extracted from variance analyses separating time and space variabilities on the rock glacier surface to provide an average‐wide time signal. We show that changes in velocity from year to year are virtually uniform at all locations with homogeneous accelerations or decelerations on the scale of the rock glacier as a whole. The spatial structure of velocity was found to be nearly at steady state over 35 years. Nonlinear effects are located in low‐velocity areas such as the rock glacier margins where accelerations/decelerations tend to be proportional to the local velocity. Over the period of record, a long‐term trend in rock glacier acceleration was detected with a rate of +0.2 m/yr per decade. Two main phases of acceleration were identified from the mid‐1980s to 1999 and from 2010 to 2015. In between, those two periods were interrupted by a 10‐year period of almost steady‐state velocities with an abrupt deceleration from 2006 to 2009 of −0.35 m/yr. The process of internal increases in ice temperatures alone (and associated changes in creep rates) would seem insufficient to explain the long‐term rise of surface velocities and their annual variations. Changes in the liquid water are a possible contributing factor, due to the injection of seasonal water caused by melting snow cover or internal melt due to heat generated by enhanced ice creep and friction in the ice/debris mixture.
{"title":"Changes in surface velocities over four decades on the Laurichard rock glacier (French Alps)","authors":"E. Thibert, Xavier Bodin","doi":"10.1002/ppp.2159","DOIUrl":"https://doi.org/10.1002/ppp.2159","url":null,"abstract":"The longest time series of surface velocities recorded on a rock glacier in the French Alps, covering more than three decades, has been recorded since 1983 on the Laurichard rock glacier (Ecrins range). The time signal of velocity changes is extracted from variance analyses separating time and space variabilities on the rock glacier surface to provide an average‐wide time signal. We show that changes in velocity from year to year are virtually uniform at all locations with homogeneous accelerations or decelerations on the scale of the rock glacier as a whole. The spatial structure of velocity was found to be nearly at steady state over 35 years. Nonlinear effects are located in low‐velocity areas such as the rock glacier margins where accelerations/decelerations tend to be proportional to the local velocity. Over the period of record, a long‐term trend in rock glacier acceleration was detected with a rate of +0.2 m/yr per decade. Two main phases of acceleration were identified from the mid‐1980s to 1999 and from 2010 to 2015. In between, those two periods were interrupted by a 10‐year period of almost steady‐state velocities with an abrupt deceleration from 2006 to 2009 of −0.35 m/yr. The process of internal increases in ice temperatures alone (and associated changes in creep rates) would seem insufficient to explain the long‐term rise of surface velocities and their annual variations. Changes in the liquid water are a possible contributing factor, due to the injection of seasonal water caused by melting snow cover or internal melt due to heat generated by enhanced ice creep and friction in the ice/debris mixture.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2022-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44202398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Jiang, Siru Gao, A. Lewkowicz, Hongting Zhao, Shou-ji Pang, Qingbai Wu
An active layer detachment slide (ALDS) in the interior portion of the Qinghai–Tibet Plateau (QTP) was investigated within 2 days of its formation on September 21, 2018. The ALDS developed on a relatively gentle slope (4.8° to 9°) at an elevation of 4,850 m above sea level (asl) and was about 145 m long and 45 m wide, with a headscarp 2.2–2.5 m high. Analyses of meteorological data and soil temperatures indicated that it was probably triggered by a record thaw depth which intersected a layer with high ice content at the base of the active layer and in the top of the permafrost. Based on the time window, the minimum downslope velocity of the main slide mass was about 20 m/h which is higher than previously reported values. The ALDS ran into the embankment of the Qinghai–Tibet Railway (QTR) but did not damage the railbed. However, extensive rehabilitation of the slope was needed subsequent to the failure to clear the slide mass and as minor headscarp recession and thaw settlement continued on the slope. In this work, we describe this feature and the most likely mechanisms of development.
{"title":"Development of a rapid active layer detachment slide in the Fenghuoshan Mountains, Qinghai–Tibet Plateau","authors":"G. Jiang, Siru Gao, A. Lewkowicz, Hongting Zhao, Shou-ji Pang, Qingbai Wu","doi":"10.1002/ppp.2151","DOIUrl":"https://doi.org/10.1002/ppp.2151","url":null,"abstract":"An active layer detachment slide (ALDS) in the interior portion of the Qinghai–Tibet Plateau (QTP) was investigated within 2 days of its formation on September 21, 2018. The ALDS developed on a relatively gentle slope (4.8° to 9°) at an elevation of 4,850 m above sea level (asl) and was about 145 m long and 45 m wide, with a headscarp 2.2–2.5 m high. Analyses of meteorological data and soil temperatures indicated that it was probably triggered by a record thaw depth which intersected a layer with high ice content at the base of the active layer and in the top of the permafrost. Based on the time window, the minimum downslope velocity of the main slide mass was about 20 m/h which is higher than previously reported values. The ALDS ran into the embankment of the Qinghai–Tibet Railway (QTR) but did not damage the railbed. However, extensive rehabilitation of the slope was needed subsequent to the failure to clear the slide mass and as minor headscarp recession and thaw settlement continued on the slope. In this work, we describe this feature and the most likely mechanisms of development.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2022-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48600790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Forte, H. French, R. Raffi, I. Santin, M. Guglielmin
The results of a combined geophysical and geomorphological investigation of thermal‐contraction‐crack polygons near Gondwana station (Germany) in northern Victoria Land (Antarctica) are reported. An area of about 20,000 m2 characterized by random orthogonal polygons was investigated using integrated ground penetrating radar, electrical resistivity tomography, geomorphological surveys, and two trench excavations. The polygons are well developed only at elevations higher than 6–7 m above current sea level on Holocene‐age raised beaches. It is concluded that the polygons are composite in nature because the shallow linear depressions that outline the polygons are underlain by fissures that can contain both sandy gravel and foliated ice (i.e., ice wedges) even in the same polygon network and at distances of just a few meters. Unexpectedly, most of the polygons follow the border of the raised beaches and develop in correspondence with stratigraphic layers dipping toward the sea, imaged by ground penetrating radar (GPR) profiles and interpreted as prograding layers toward the present‐day shoreline.
{"title":"Investigations of polygonal patterned ground in continuous Antarctic permafrost by means of ground penetrating radar and electrical resistivity tomography: Some unexpected correlations","authors":"E. Forte, H. French, R. Raffi, I. Santin, M. Guglielmin","doi":"10.1002/ppp.2156","DOIUrl":"https://doi.org/10.1002/ppp.2156","url":null,"abstract":"The results of a combined geophysical and geomorphological investigation of thermal‐contraction‐crack polygons near Gondwana station (Germany) in northern Victoria Land (Antarctica) are reported. An area of about 20,000 m2 characterized by random orthogonal polygons was investigated using integrated ground penetrating radar, electrical resistivity tomography, geomorphological surveys, and two trench excavations. The polygons are well developed only at elevations higher than 6–7 m above current sea level on Holocene‐age raised beaches. It is concluded that the polygons are composite in nature because the shallow linear depressions that outline the polygons are underlain by fissures that can contain both sandy gravel and foliated ice (i.e., ice wedges) even in the same polygon network and at distances of just a few meters. Unexpectedly, most of the polygons follow the border of the raised beaches and develop in correspondence with stratigraphic layers dipping toward the sea, imaged by ground penetrating radar (GPR) profiles and interpreted as prograding layers toward the present‐day shoreline.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2022-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43776368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We evaluated the spatial distribution and morphological variability of thermal contraction crack polygon (TCCP) networks across Nunavik, a 440,000‐km2 region of northern Québec that spans the northward transition from discontinuous to continuous permafrost. A population of 4,567 TCCP sites was sampled and analyzed from 80,737 georeferenced high‐resolution aerial photographs and 264,504 km2 of ESRI satellite basemaps. For each site, six parameters were inventoried and compiled into a database: (a) network geometric arrangement; (b) intersection angles; (c) number of subdivisions and nested polygons (referred to as generations of development); (d) dominant polygon morphology; (e) surficial geology; and (f) vegetation cover. Statistical analyses of the tabulated data revealed a strong association between Holocene glacial, glacio‐fluvial, fluvial, marine, and organic landforms and the different intersections angles in the networks, providing insight into how the processes of thermal contraction cracking function and manifest geomorphically across varied permafrost landscapes. Orthogonal polygons (intersection angle of 90°) dominate on flat terrains where the thermo‐mechanical stresses are probably spatially homogeneous. Hexagonal (angles of 120°) and poorly structured polygons tend to form where topography variability probably generates heterogeneous heat flow patterns and thermo‐mechanical stresses in the ground, resulting in irregular cracking patterns.
{"title":"Thermal contraction crack polygons in Nunavik (northern Quebec): Distribution and development of polygonal patterned ground","authors":"Alexandre Chiasson, M. Allard","doi":"10.1002/ppp.2150","DOIUrl":"https://doi.org/10.1002/ppp.2150","url":null,"abstract":"We evaluated the spatial distribution and morphological variability of thermal contraction crack polygon (TCCP) networks across Nunavik, a 440,000‐km2 region of northern Québec that spans the northward transition from discontinuous to continuous permafrost. A population of 4,567 TCCP sites was sampled and analyzed from 80,737 georeferenced high‐resolution aerial photographs and 264,504 km2 of ESRI satellite basemaps. For each site, six parameters were inventoried and compiled into a database: (a) network geometric arrangement; (b) intersection angles; (c) number of subdivisions and nested polygons (referred to as generations of development); (d) dominant polygon morphology; (e) surficial geology; and (f) vegetation cover. Statistical analyses of the tabulated data revealed a strong association between Holocene glacial, glacio‐fluvial, fluvial, marine, and organic landforms and the different intersections angles in the networks, providing insight into how the processes of thermal contraction cracking function and manifest geomorphically across varied permafrost landscapes. Orthogonal polygons (intersection angle of 90°) dominate on flat terrains where the thermo‐mechanical stresses are probably spatially homogeneous. Hexagonal (angles of 120°) and poorly structured polygons tend to form where topography variability probably generates heterogeneous heat flow patterns and thermo‐mechanical stresses in the ground, resulting in irregular cracking patterns.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41342463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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