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Huijun Jin - One of the best experts on this subject based on the ideXlab platform.
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very large Cryoturbation structures of last permafrost maximum age at the foot of qilian mountains ne tibet plateau china a discussion
Permafrost and Periglacial Processes, 2017Co-Authors: Stuart A Harris, Huijun JinAbstract:Intensely cold conditions occurred during part of the last major glaciation of the mountains and Qinghai–Tibet Plateau in northeast China but their chronology is constrained by few limiting ages. At the Mengyuan section, on the northeastern margin of the Qilian Mountains, sandy silt provided three OSL ages that suggest deposition during a very cold, dry period in northeastern China between c. 29 and 19 ka (early part of marine isotope stage (MIS) 2). Load‐casting into the underlying outwash gravel occurred during climate amelioration. In some cases, the sandy silt infilled the spaces left by underlying thawing blocks of ice without collapse of the surrounding gravel. The gravel must therefore be older than c. 30 ka and was probably deposited by outwash from glaciers on the higher parts of the Qilian Mountains during MIS 3. Included in them were buried contemporaneous or remnant blocks of glacial ice. Subsequently the surface became flat by unknown processes and was finally covered by a thin loess dating from 2.7 ka, indicating it was deposited in the first warmer period in the Neoglacial sequence of events. Thus, the last major cold event spanned the period through isotope stages 2 and 3 in this area (57 to c. 19 ka), during which the dominant effects of glaciation of the mountain tops were replaced by intensely dry, cold permafrost conditions for c. 10 ka. Copyright © 2017 John Wiley & Sons, Ltd.
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early to mid holocene lake high stand sediments at lake donggi cona northeastern tibetan plateau china
Quaternary Research, 2013Co-Authors: Elisabeth Dietze, Huijun Jin, Bernd Wunnemann, Kai Hartmann, Bernhard Diekmann, Georg Stauch, Sizhong Yang, Frank LehmkuhlAbstract:Lake high-stand sediments are found in three onshore terraces at Lake Donggi Cona, northeastern Tibetan Plateau, and reveal characteristics of hydrological changes on lake shorelines triggered by climate change, geomorphological processes, and neo-tectonic movements. The terraces consist of fluvial–alluvial to littoral-lacustrine facies. End-member modeling of grain-size distributions allowed quantification of sediment transport processes and relative lake levels during times of deposition. Radiocarbon dating revealed higher than modern lake levels during the early and mid Holocene. Lake levels follow the trend of Asian monsoon dynamics, and are modified by local non-climatic drivers. Site-specific impacts explain fluctuations during the initial lake-level rise ~ 11 cal ka BP. Maximum lake extension reached ~ 9.2 cal ka BP, at ~ 16.5 m above present lake level (a.p.l.l.). Littoral and lacustrine sediment deposition paused during a phase of fluvial activity and post-depositional Cryoturbations at ~ 8.5 cal ka BP, when the lake level fell to ~ 8 m a.p.l.l. After a second maximum at ~ 7.5 cal ka BP, lake level declined slightly at ~ 6.8 cal ka BP, probably due to a non-climatic pulse that caused lake opening. The level remained high until a transition towards drier conditions ~ 4.7 cal ka BP. Though discontinuous, high-stand sediments provide a unique, high-resolution archive.
James G. Bockheim - One of the best experts on this subject based on the ideXlab platform.
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sulfurization acid sulfate soils and active layer monitoring at the semiarid seymour island antarctica
Geoderma Regional, 2020Co-Authors: Davi Feital Gjorup, Carlos Ernesto Goncalves Reynaud Schaefer, Felipe Nogueira Bello Simas, Marcio Rocha Francelino, Roberto Ferreira Machado Michel, James G. BockheimAbstract:Abstract Soils and permafrost occurrence and behavior at the Weddell Sea zone, located in the key zone of climatic transition between Maritime Antarctica and Continental Antarctica, remain little studied. We studied the main chemical, physical and mineralogical properties of representative soil profiles of the northern part of Seymour Island, discussing soil formation processes and the active-layer thermal and water regimes of a representative site. Soil sampling and installation of the monitoring site was carried out in the northern part of Seymour Island. Permafrost was generally detected within the first 100 cm of depth, except at coastal areas, although typical periglacial features (Cryoturbation), vegetation growth and organic matter accumulation were negligible or absent. Well-drained soils showed low Electric Conductivity (EC), indicating leaching of salts, whereas near-permafrost layers showed higher values of EC. Salt content and EC increased at lower altitudes. Two major groups of soils were identified: (i) Acid Sulfate Soils (ASS); and (ii) Weakly Developed Alkaline Soils (WDAS). Acid Sulfate Soils develop under the influence of sulfide-containing material under oxidizing conditions, and are the most developed and weathered in the area, presenting significant morphological, mineralogical and chemical traits, such as low pH values, sulfuric B horizons, and the presence of secondary minerals indicating sulfurization process, such as jarosite and low crystallinity iron oxide. Weakly Developed Alkaline Soils develop under low chemical and mineralogical transformation, where physical weathering is a key process. These soils present high pH and high content of primary minerals in the clay fraction, mainly K-feldspars and plagioclase. The active-layer thermal regime is typical of periglacial environments, with seasonal temperature variations of soil around 0 °C, with prevailing negative temperatures. Regional climate was comparable with Continental Antarctica, whereas the pedoclimate (active layer thickness, soil water content) showed closer affinity with Maritime Antarctica. Some soil forming processes are driven by pedoclimate, and favored by the unfrozen and free-drainage conditions during the summer season; however, the main factor influencing soil development is parent material. The main soil formation processes are sulfurization, cryoclasty and halomorphism, since the semiarid dry climate does not favor Cryoturbation and organic matter accumulation.
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soil landscape interplays at harmony point nelson island maritime antarctica chemistry mineralogy and classification
Geomorphology, 2019Co-Authors: William Fortes Rodrigues, James G. Bockheim, Carlos Ernesto Goncalves Reynaud Schaefer, Fabio Soares De Oliveira, Mariangela Garcia Praca Leite, Teodoro Gauzzi, Jair PutzkeAbstract:Abstract Soils and landforms of Nelson Island remain one of the least studied in the South Shetlands Archipelago, despite that it is one of the oldest ice-free areas and is strongly vegetated. In this paper, we examine the main processes and factors of soil formation at Harmony Point and the relation of soils to landforms, vegetation and lithology. To achieve the goals, 26 pedons were collected and studied from a 4 km2 ice-free area at Harmony Point (S62°18′; W059°10′) on the southern area of Nelson Island (Maritime Antarctica). The soils were sampled on all representative local landforms, including three levels of uplifted marine terraces up to cryoplanated plateau, waterlogged depressions, rock felsenmeer, debris slopes and patterned ground, and a paraglacial border of the ice cap (270 m a.s.l). Sampling along the cryoplanated plateau was carried out along a gradient extending inland from the margins of the Ice Cap; and sampling of the marine terraces was performed along a chronosequence under varying bird-nesting influence and age. The main pedogenetic processes observed in this area are marked phosphatization, melanization from the accumulation of organic matter, and Cryoturbation. Soil development varies from weakly developed, shallow, stony and cryoturbated to well-developed and organic-rich, phosphate soils with colors ranging from grayish to brown. The mineralogical composition of the clay fraction contains secondary minerals, indicating the active role of chemical weathering. Ornithogenic soils have mature phosphate minerals such as vivianite and taranakite, as well as poorly crystalline leucophosphite. Intensively cryoturbated soils are underlain by permafrost and are classified as Typic Haploturbels; polygonal soils are widespread on the cryoplanated plateau. Areas without permafrost were classified as Typic Gelorthents. Phosphatization is a dominant soil-forming process in this area and is associated with past and present-day guano accumulation by bird nesting and has led to the the development of deeper Ornithogenic Haplorthels. The ornithogenic soils occur at different topographic levels on the cryplanated platform and marine terraces. High P concentrations can be used as a proxy of the past nesting birds' activities, with far-reaching implications, especially with regards to vegetation growth and microbial activity and diversity.
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landform and soil development in the mcmurdo dry valleys antarctica a regional synthesis
Arctic Antarctic and Alpine Research, 2002Co-Authors: James G. BockheimAbstract:The McMurdo Valleys Mapping Project (VALMAP) contains soils data collected from 473 sites in the McMurdo Dry Valleys (77?07.5-78?00'S; 160?-164?E), Antarctica. The database includes surface boulder lithology, frequency, and weathering features; observations of patterned ground, permafrost, and ground-ice forms; detailed soil profile descriptions; laboratory characterization; and classification of the soils. Each site was located on 1:50,000 topographic maps from aerial photographs and elevation measurements, digitized, and entered into an ArcInfo Geographic Information System. The sites are arrayed along an ecoclimatic gradient that includes 21 coastal sites (4.4% of total), 109 inland valley floor sites (23%), 196 inland valley side sites (41%), 136 upland valley sites (29%), and 11 plateau fringe sites (2.3% of total). Whereas ice-cemented permafrost was predominant at coastal sites and along the polar plateau, 42% of the sites had dry permafrost in the upper 1 m. Massive ice occurs to a limited extent as ice-wedge polygons, ice-cored drift, and rock glaciers. Sand-wedge casts in upland valleys attest to a recession of the ice-cemented permafrost to greater depths over time. The most strongly developed soils and weathering features are on valley floors and in upland valleys where older deposits and landforms occur. The distribution of anions in soil:water extracts is reflective of air mass movement, with most soils reflecting a coastal source. Seventy percent of the soils examined in the McMurdo Dry Valleys are classified as Anhyorthels reflecting the lack of Cryoturbation in the cold desert Antarctic environment.
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soils and Cryoturbation in moist nonacidic and acidic tundra in the kuparuk river basin arctic alaska u s a
Arctic and alpine research, 1998Co-Authors: James G. Bockheim, D A Walker, L R Everett, F E Nelson, N I ShiklomanovAbstract:We compared 22 pedons derived from silty materials in moist nonacidic tundra (MNT) and moist acidic tundra (MAT) in the arctic foothills of the 9200-km2 Kuparuk River basin in northern Alaska. Soils in MNT have thinner organic horizons, a significantly thicker active layer, and greater Cryoturbation than soils in MAT. The quantities of clay and organic-plus-inorganic C in the upper 100 cm are comparable; however, soils in MNT have significantly greater amounts of extractable Ca, Mg, and sum of base cations and significantly lower amounts of exchangeable acidity and Al than soils in MAT. Tissues from forbs, sedges, and woody shrubs in MNT have two to three times as much Ca as the same or similar species in MAT. The area of nonsorted circles was significantly greater in MNT (9.6%) than in MAT (0.9%). Although the existence of nonacidic tundra in the Arctic has been known for some time, its origin and distribution have not been fully explained. Our data link soil and vegetation properties and indicate that Cryoturbation plays an important role in maintaining MNT in arctic Alaska.
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recognition of Cryoturbation for classifying permafrost affected soils
Geoderma, 1998Co-Authors: James G. Bockheim, C TarnocaiAbstract:Cryoturbation is a dominant pedologic process in permafrost-affected soils and is used to delineate Gelisols in soil taxonomy and Cryosols in the Canadian and recently proposed World Reference Base for Soil Resources, and Cryozems in Russian systems of soil classification. In this paper we summarize evidence for Cryoturbation that can be used for classifying soils containing permafrost. Based on a literature review and our own observations, Cryoturbation in the soil profile is manifested by irregular and broken horizons and textural bands, involutions, organic matter accumulation on the permafrost table, oriented stones, silt caps and accumulations, and deformed soil material associated with movements due to ice- and sand-wedge growth.
Dimitri Vandenberghe - One of the best experts on this subject based on the ideXlab platform.
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very large Cryoturbation structures of last permafrost maximum age at the foot of the qilian mountains ne tibet plateau china
Permafrost and Periglacial Processes, 2016Co-Authors: J Vandenberghe, Xianyan Wang, Dimitri VandenbergheAbstract:Unusually large Cryoturbation structures (4–4.5 m amplitude), developed in channel gravels and overbank fine-grained deposits of a river terrace on the NE Tibet Plateau, China, were formed by loadcasting as late Pleistocene-age permafrost degraded. It is suggested that the oversaturation and liquefaction of the thawed sediments could have been achieved only if the amount of ice in the upper 4–4.5 m of terrace sediments had been very high. The structures, dated at around 26–20 ka by OSL, point to the presence of a massive icy layer existing within a permafrost body during the Last Permafrost Maximum. Copyright © 2015 John Wiley & Sons, Ltd.
Mcleod Malcolm - One of the best experts on this subject based on the ideXlab platform.
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Soil and permafrost distribution, soil characterisation and soil vulnerability to human foot trampling, Wright Valley, Antarctica
University of Waikato, 2012Co-Authors: Mcleod MalcolmAbstract:Soils and shallow permafrost in Wright Valley, Antarctica were mapped at a scale of 1:50 000 to depict their spatial distribution, and sampled to determine the main drivers for the soil classification. In the cold desert of Wright Valley the Gelisol order of Soil Taxonomy was used to classify the soils. Soils on younger surfaces, associated with Lower Wright Glacier, Upper Wright Glacier and alpine glaciers, contain massive ice within 100 cm of the soil surface and are classified as Glacic Haplorthels or Glacic Haploturbels where there is field evidence of Cryoturbation. As a generalization, at either end of the valley, soil moisture recharge from moist coastal air masses (eastern end) and blowing snow drifts maintain the depth to permafrost in which ice-cement occurs at
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Soil and permafrost distribution, soil characterisation and soil vulnerability to human foot trampling, Wright Valley, Antarctica
'University of Waikato', 2012Co-Authors: Mcleod MalcolmAbstract:Soils and shallow permafrost in Wright Valley, Antarctica were mapped at a scale of 1:50 000 to depict their spatial distribution, and sampled to determine the main drivers for the soil classification. In the cold desert of Wright Valley the Gelisol order of Soil Taxonomy was used to classify the soils. Soils on younger surfaces, associated with Lower Wright Glacier, Upper Wright Glacier and alpine glaciers, contain massive ice within 100 cm of the soil surface and are classified as Glacic Haplorthels or Glacic Haploturbels where there is field evidence of Cryoturbation. As a generalization, at either end of the valley, soil moisture recharge from moist coastal air masses (eastern end) and blowing snow drifts maintain the depth to permafrost in which ice-cement occurs at 70 cm, are classified as Salic or Typic Anhyorthels or, where there is field evidence of Cryoturbation, Anhyturbels. While mapping soils in Wright Valley, the distribution and nature of the shallow permafrost were also investigated. Three classes of permafrost were established to coincide with definitions or conditions within Soil Taxonomy viz: permafrost with ice-cement at 70 cm, and massive ice. A definition for a petrosalic horizon is proposed based on the properties of a salic horizon and the indurated nature of petrocalcic/petrogypsic horizons. The horizon is likely to occur only in the cold desert climate zones of Antarctica. A rapid method to determine soil vulnerability to human foot traffic was developed. As vulnerability is the product of disturbance and rehabilitation, the method is based on the disturbance of 10 foot prints at a site multiplied by a soil rehabilitation factor based on the soil weathering stage. Although fine-grained aeolian sands are easily disturbed they also rehabilitate rapidly in the windy conditions of Wright Valley. In contrast, old stable soils have a tight cobbly desert pavement with reddish desert varnish and often show less foot print disturbance. When cobbles are overturned, however, fresh rock with thick salt accumulations and without desert varnish is exposed. It takes much time for the desert varnish to re-establish. The spatial distribution of Soil Taxonomy soil classes, nature of the permafrost and soil vulnerability to human traffic are presented as three separate maps at 1:50 000 scale and as live GIS files
J Vandenberghe - One of the best experts on this subject based on the ideXlab platform.
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very large Cryoturbation structures of last permafrost maximum age at the foot of the qilian mountains ne tibet plateau china
Permafrost and Periglacial Processes, 2016Co-Authors: J Vandenberghe, Xianyan Wang, Dimitri VandenbergheAbstract:Unusually large Cryoturbation structures (4–4.5 m amplitude), developed in channel gravels and overbank fine-grained deposits of a river terrace on the NE Tibet Plateau, China, were formed by loadcasting as late Pleistocene-age permafrost degraded. It is suggested that the oversaturation and liquefaction of the thawed sediments could have been achieved only if the amount of ice in the upper 4–4.5 m of terrace sediments had been very high. The structures, dated at around 26–20 ka by OSL, point to the presence of a massive icy layer existing within a permafrost body during the Last Permafrost Maximum. Copyright © 2015 John Wiley & Sons, Ltd.
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permafrost and periglacial features Cryoturbation structures
Reference Module in Earth Systems and Environmental Sciences#R##N#Encyclopedia of Quaternary Science (Second Edition), 2013Co-Authors: J VandenbergheAbstract:Six types of Cryoturbation structures (sedimentary deformations of cryogenic origin) can be distinguished and attributed to different mechanisms of formation and specific environmental conditions. Cryoturbations may result from (1) gravitational loading in thawing soil (‘periglacial loading’), (2) hydrostatic pressure between frozen parts of the subsoil (‘cryohydrostatic pressure’), or (3) ice-induced pressures due to differential frost penetration (‘cryostatic heave’). The first, and most common, process requires a reversed density gradient and conditions of liquefaction that are possible only during thaw of underlying frozen subsoil. The other two processes occur during freezing. Only large-amplitude deformations due to periglacial loading indicate the existence of perennially frozen ground and, therefore, provide important paleoclimatic proxy indicators. The other Cryoturbation types do not require permafrost conditions; they simply require deep seasonal frost or repeated freeze–thaw cycles. Cryoturbations may enhance the storage of organic carbon in the soil and influence the global carbon cycle.
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periglacial landforms Cryoturbation structures
Encyclopedia of Quaternary Science, 2007Co-Authors: J VandenbergheAbstract:Different types of Cryoturbation (sedimentary deformations of cryogenic origin) are distinguished, interpreted in terms of mechanisms of formation and linked to their specific environmental conditions. Cryoturbations may originate from gravitational loading in the thawing soil (‘periglacial loading’), from hydrostatic pressure between frozen parts of the subsoil (‘cryohydrostatic pressure’), or from pressures due to differential frost penetration (‘cryostatic heave’). The first, and most common, process requires a reversed density gradient and conditions of liquefaction that are only possible during the degradation of the underlying frozen subsoil. The other two processes occur during the freezing process. Only large-amplitude deformations due to periglacial loading are indicative of the existence of perennially frozen ground and are therefore important paleoclimatic proxy indicators. All other Cryoturbation types do not necessarily require permafrost conditions, but deep seasonal frost or repeated frost-thaw alternations may be sufficient.