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Articles de revues sur le sujet « Protalus rampart »

Auteur : Grafiati
Publié le 9 mars 2023
Mis à jour le 10 mars 2023

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1

Scapozza, C. « Investigation on protalus ramparts in the Swiss Alps ». Geographica Helvetica 70, no 2 (14 avril 2015) : 135–39. http://dx.doi.org/10.5194/gh-70-135-2015.

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Abstract. The origin and classification of landforms denominated as "protalus ramparts" in the scientific literature is a problem that is far from being resolved. The main objective of this contribution is to support a permafrost-related definition of protalus ramparts. If we consider the Alpine framework, protalus ramparts are generally very rare landforms; by contrast, the Alpine periglacial belt is characterised by a large diffusion of talus slopes and talus rock glaciers. The investigations carried out in six sites of the Valais Alps (Switzerland) allow eight major "diagnostic criteria" to be presented that help to define protalus ramparts in Alpine environments and that support the permafrost-related genesis of most of them. The major source of controversy is related to the use of the term protalus rampart to designate both a nivo-gravitational landform (also called "pronival ramparts") and a permafrost-related landform. All the considerations presented here allow an active protalus rampart to be defined simply as a (small) active talus rock glacier.
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Hedding, David W., Paul D. Sumner, Stephen D. Holness et K. Ian Meiklejohn. « Formation of a pronival rampart on sub-Antarctic Marion Island ». Antarctic Science 19, no 4 (2 août 2007) : 443–50. http://dx.doi.org/10.1017/s0954102007000582.

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AbstractThe formation of a pronival (protalus) rampart on sub-Antarctic Marion Island is investigated. Morphological attributes show debris at the angle of repose on the rampart's proximal slope and at a lower angle on the distal slope. Relative-age dating, based on the percentage moss cover and weathering rind thickness of the clastic component, indicates accumulation mainly on the proximal slope and rampart crest, implying upslope (retrogressive) accumulation. This contrasts with a previously published model for pronival ramparts, which proposes rampart growth by addition of material to the distal slope. Development of the Marion Island rampart is suggested to result from the control exerted by a relatively low-angled surface and a shrinking snowbed. A small debris step formed on the proximal slope appears to be a response to decreased snowfalls due to changing climate over the last c. 50 years. Growth rate of the rampart is considered to be variable during the Holocene in response to changes in climate and debris supply.
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Shakesby, R. A. « Pronival (protalus) ramparts : a review of forms, processes, diagnostic criteria and p alaeoenvi ronmental implications ». Progress in Physical Geography : Earth and Environment 21, no 3 (septembre 1997) : 394–418. http://dx.doi.org/10.1177/030913339702100304.

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Most of the literature on pronival (protalus) ramparts deals with supposed fossil examples with very few studies devoted to active features and/or observed processes. Not surprisingly, this has led to circular reasoning and assumptions about typical rampart form, constituent material and genesis that have been shown to be inadequate or spurious from the few detailed investigations of actively forming ramparts so far carried out. Nevertheless, reliance continues to be placed on the characteristics of fossil features in the search for previously unidentified fossil examples. This article provides a critical review of rampart terminology, morphology and sedimentology, mechanisms, 'diagnostic' criteria, position in a continuum of talus-derived landforms and palaeoclimatic significance. It is suggested that the descriptor pronival is preferable to the widely used protalus, as the latter is misleadingly restrictive in terms of the known range of possible locations. Greater variability in terms of form and mechanisms of formation than most workers assume is indicated by recent studies of active features, with multiple as well as single ridges, fines and edge-worn as well as coarse angular clasts being found, and a variety of supranival and also subnival processes regarded as possibly contributing to rampart formation. It is concluded that only when further investigations of actively forming ramparts have been carried out, will it be possible to compile a reliable list of criteria for dist inguishing ramparts from moraines, protalus rock glaciers and other bedrock cliff-foot deposi tional forms. Correct identification of fossil ramparts may then lead to a better understanding of 1) their place in a continuum of talus-derived landforms; and 2) their potential as palaeoclimatic indicators.
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Hedding, D. W. « Pronival rampart and protalus rampart : a review of terminology ». Journal of Glaciology 57, no 206 (2011) : 1179–80. http://dx.doi.org/10.3189/002214311798843241.

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Ballantyne, Colin K. « The conachair protalus Rampart, St Kilda ». Scottish Geographical Journal 118, no 4 (1 janvier 2002) : 343–50. http://dx.doi.org/10.1080/00369220218737156.

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Ballantyne, Colin K., et Douglas I. Benn. « Glaciological constraints on protalus rampart development ». Permafrost and Periglacial Processes 5, no 3 (août 1994) : 145–53. http://dx.doi.org/10.1002/ppp.3430050304.

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7

Hedding, David W. « Pronival ramparts ». Progress in Physical Geography : Earth and Environment 40, no 6 (28 novembre 2016) : 835–55. http://dx.doi.org/10.1177/0309133316678148.

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Pronival ramparts are debris ridges formed at the downslope margins of perennial or semi-permanent snowbeds beneath bedrock cliffs. These landforms, also previously known as protalus ramparts, are located in periglacial environments, but the apparent simplicity of rampart formation made these landforms far less interesting than other modified forms of talus in cold environments. As a result, limited research, use of supposed relict examples and assumed formative mechanisms led to the misidentification of ramparts, circular arguments regarding genesis and inappropriate palaeo-environmental inferences. Several advances have, however, been made in the past few decades, particularly where actively-forming ramparts have been studied. Thus, this paper provides a review of research on pronival ramparts. In particular, focus is placed on the advances made in our understanding of rampart genesis, identification (diagnostic criteria) and palaeo-environmental significance. Notable advances include the development of a retrogressive model of rampart genesis to supplement the conventional downslope model of development, revised diagnostic criteria for field identification and the use of calibration equations during Schmidt-hammer exposure dating of pronival rampart. The use of pronival ramparts as palaeo-environmental indicators is also examined to determine what relict examples of these landforms may reveal about past climates.
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8

Brook, Martin S., et Jacob Williams. « A Relict Pronival (Protalus) Rampart in the Tararua Range, North Island, New Zealand ». Permafrost and Periglacial Processes 24, no 1 (2 décembre 2012) : 67–74. http://dx.doi.org/10.1002/ppp.1759.

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9

Harris, Charles. « Some observations concerning the morphology and sedimentology of a protalus rampart, Okstindan, Norway ». Earth Surface Processes and Landforms 11, no 6 (novembre 1986) : 673–76. http://dx.doi.org/10.1002/esp.3290110610.

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Curry, Alastair M., John Walden et D. Allan Cheshire. « The Nant Ffrancon ‘protalus rampart’ : evidence for Late Pleistocene paraglacial landsliding in Snowdonia, Wales ». Proceedings of the Geologists' Association 112, no 4 (janvier 2001) : 317–30. http://dx.doi.org/10.1016/s0016-7878(01)80011-0.

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11

Ono, Yugo, et Teiji Watanabe. « A Protalus Rampart Related to Alpine Debris Flows in the Kuranosuke Cirque Northern Japanese Alps ». Geografiska Annaler. Series A, Physical Geography 68, no 3 (1986) : 213. http://dx.doi.org/10.2307/521461.

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FUKUI, Kotaro. « Permafrost and Surface Movement of the Protalus Rampart in the Kuranosuke Cirque, Tateyama Mountains, Japan. » Journal of Geography (Chigaku Zasshi) 111, no 4 (2002) : 564–73. http://dx.doi.org/10.5026/jgeography.111.4_564.

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Ono, Yugo, et Teiji Watanabe. « A Protalus Rampart Related to Alpine Debris Flows in the Kuranosuke Cirque Northern Japanese Alps ». Geografiska Annaler : Series A, Physical Geography 68, no 3 (octobre 1986) : 213–23. http://dx.doi.org/10.1080/04353676.1986.11880175.

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14

Shakesby, Richard A., John A. Matthews, Mark S. Berrisford et Lindsey J. Mcewen. « Snow‐push processes in pronival (protalus) rampart formation : geomorphological evidence from smørbotn, romsdalsalpane, southern norway ». Geografiska Annaler : Series A, Physical Geography 81, no 1 (avril 1999) : 31–45. http://dx.doi.org/10.1111/j.0435-3676.1999.00047.x.

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15

Ballantyne, Colin K. « Protalus rampart development and the limits of former glaciers in the vicinity of Baosbheinn, Wester Ross ». Scottish Journal of Geology 22, no 1 (mai 1986) : 13–25. http://dx.doi.org/10.1144/sjg22010013.

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Ballantyne, Colin K., et John O. Stone. « Rock-slope failure at Baosbheinn, Wester Ross, NW Scotland : age and interpretation ». Scottish Journal of Geology 45, no 2 (1 octobre 2009) : 177–81. http://dx.doi.org/10.1144/0036-9276/01-388.

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SynopsisA massive arcuate ridge composed of large tabular boulders below a failure scar at the NW extremity of Baosbheinn has previously been interpreted as a protalus rampart or talus rock glacier of Loch Lomond Stadial (c. 12.9–11.5 ka) age. The ridge occurs downslope of a rockslide failure zone flanked by steep rock buttresses, and is here reinterpreted as consisting of rockslide debris produced by failure of 0.5–0.6 Mt of rock from the backing slope. The runout debris is inferred to have lost momentum as it impacted the basal break of slope and consequently accumulated as a steep-fronted ridge with a gentle backing depression, partly burying a lateral moraine attributed to the Wester Ross Readvance (WRR) of c. 14.0–13.5 ka. Cosmogenic 10Be exposure ages for large boulders on the rockslide runout debris indicate that the rockslide occurred between 14.0 ± 1.6 ka and 13.3 ± 1.2 ka under cool temperate conditions during the Lateglacial Interstade. Failure probably occurred within a few centuries after deposition of the over-ridden WRR moraine, and is attributed to rock-slope weakening due to deglacial unloading and consequent paraglacial stress release, possibly enhanced by thaw of ice within bedrock joints.
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17

Thompson, David J. « Talus fabric in Tuckerman Ravine, New Hampshire : Evidence for a tongue-shaped rock glacier ». Géographie physique et Quaternaire 53, no 1 (2 octobre 2002) : 47–57. http://dx.doi.org/10.7202/004881ar.

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Abstract Tuckerman Ravine is a glacial cirque located in the White Mountains of New Hampshire. The Ravine contains four talus accumulations formed through rockfall and toppling and characterized by large joint blocks with long axes of at least one meter. Previous research has classified one of the deposits (identified as Site 1 in the current study) variously as a moraine, a lobate rock glacier, and a protalus rampart. To resolve this controversy and provide a more reliable interpretation, block fabric analysis was performed at this and the other three talus sites. A bimodal fabric distribution was encountered at Site 1 and implies that the blocks at the base of the deposit collectively met some obstruction to movement. Such arrangement is not accounted for in simple talus accumulation models or in previous interpretations. The fabric data and its other characteristics support the classification of Site 1 as a relict tongue-shaped rock glacier. Fabric analysis indicates that the majority of blocks at Sites 2, 3, and 4 have a preferred orientation in the downslope direction and that these deposits represent rockfall talus which has not experienced post-depositional movement or activity. The mere presence of the talus deposits and their locations (which include the cirque headwall) do not support the reactivation of cirque glaciers in the White Mountains during the Holocene.
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18

Hall, Kevin, et Ian Meiklejohn. « Some Observations Regarding Protalus Ramparts ». Permafrost and Periglacial Processes 8, no 2 (1997) : 245–49. http://dx.doi.org/10.1002/(sici)1099-1530(199732)8:2<245 ::aid-ppp246>3.0.co;2-r.

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Villarroel, C. D., et A. P. Forte. « Spatial distribution of active and inactive rock glaciers and protalus ramparts in a sector of the Central Andes of Argentina ». Cuadernos de Investigación Geográfica 46, no 1 (24 juin 2020) : 141–58. http://dx.doi.org/10.18172/cig.4272.

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Rock glaciers and protalus ramparts are two of the main morphological features of the Central Andes in the Province of San Juan, Argentina. This sector of the Andes has one of the highest densities of occurrence of rock glaciers in the world. In this region, which has semiarid climatic characteristics, the presence of these landforms is important due to their solid state water reserves and as water resource regulators. Their occurrence is vital in several basins where, due to the lack of glaciers, debris-covered glaciers and perennial snow patches, rock glaciers are the only solid-state water reserves. However, the topo-climatic factors controlling the development and evolution of rock glaciers and protalus ramparts are not well known, which prevents an integrated management of the basins. This contribution, first, analyzes the spatial distribution of active and inactive rock glaciers and of protalus ramparts with respect to different topographic variables in the upper section of the Santa Cruz River basin. In total, 375 landforms have been inventoried, out of which 83 are active rock glaciers, 81 are inactive and 211 are protalus ramparts, covering an area of 13.09 km2 (3.03 % of the total area). The active periglacial environment belt occurs between 4000 and 4200 m a.s.l. and slopes with a southwesterly aspect have a greater development of active rock glaciers. Secondly, the evolution of such landforms is addressed. While the development of protalus ramparts does not seem to be mainly controlled by the topographic variables analyzed, the evolution of protalus ramparts in rock glaciers would be mainly controlled by elevation and aspect. Besides, there are local topo-climatic factors that contribute to the development of such landforms.
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Colucci, R. R., C. Boccali, M. Žebre et M. Guglielmin. « Rock glaciers, protalus ramparts and pronival ramparts in the south-eastern Alps ». Geomorphology 269 (septembre 2016) : 112–21. http://dx.doi.org/10.1016/j.geomorph.2016.06.039.

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Tinkler, K. J., et J. W. Pengelly. « Protalus ramparts and related features along the niagara escarpment, niagara peninsula, ontario ». Permafrost and Periglacial Processes 5, no 3 (août 1994) : 171–84. http://dx.doi.org/10.1002/ppp.3430050306.

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Ballantyne, Colin K., et Martin P. Kirkbride. « The characteristics and significance of some lateglacial protalus ramparts in upland Britain ». Earth Surface Processes and Landforms 11, no 6 (novembre 1986) : 659–71. http://dx.doi.org/10.1002/esp.3290110609.

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Butler, David R. « NEOGLACIAL CLIMATIC INFERENCES FROM ROCK GLACIERS AND PROTALUS RAMPARTS, SOUTHERN LEMHI MOUNTAINS, IDAHO ». Physical Geography 9, no 1 (janvier 1988) : 71–80. http://dx.doi.org/10.1080/02723646.1988.10642340.

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Gordon, Lisa S., et Colin K. Ballantyne. « ‘Protalus ramparts’ on Navajo Mountain, Utah, USA : reinterpretation as blockslope-sourced rock glaciers ». Permafrost and Periglacial Processes 17, no 2 (2006) : 179–87. http://dx.doi.org/10.1002/ppp.545.

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Scotti, Riccardo, Francesco Brardinoni, Stefano Alberti, Paolo Frattini et Giovanni B. Crosta. « A regional inventory of rock glaciers and protalus ramparts in the central Italian Alps ». Geomorphology 186 (mars 2013) : 136–49. http://dx.doi.org/10.1016/j.geomorph.2012.12.028.

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Ballantyne, Colin K. « Some Observations on the Morphology and Sedimentology of Two Active Protalus Ramparts, Lyngen, Northern Norway ». Arctic and Alpine Research 19, no 2 (mai 1987) : 167. http://dx.doi.org/10.2307/1551249.

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Shakesby, Richard A., John A. Matthews et Danny McCarroll. « Pronival ("Protalus") Ramparts in the Romsdalsalpane, Southern Norway : Forms, Terms, Subnival Processes, and Alternative Mechanisms of Formation ». Arctic and Alpine Research 27, no 3 (août 1995) : 271. http://dx.doi.org/10.2307/1551958.

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SHAKESBY, RICHARD A., ALASTAIR G. DAWSON et JOHN A. MATTHEWS. « Rock glaciers, protalus ramparts and related phenomena, Rondane, Norway : a continuum of large-scale talus-derived landforms ». Boreas 16, no 3 (16 janvier 2008) : 305–17. http://dx.doi.org/10.1111/j.1502-3885.1987.tb00099.x.

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Shroder, John, et Brandon Weihs. « Mass-Movement Disturbance Regime Landscapes, Hazards, and Water Implications : Grand Teton National Park ». UW National Parks Service Research Station Annual Reports 36 (1 janvier 2013) : 74–87. http://dx.doi.org/10.13001/uwnpsrc.2013.3987.

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The Teton Range is the result of active crustal extension (normal faulting) and is the youngest range in the Rocky Mountains at approximately 2 million years old. This makes it a particularly attractive landscape to study, especially in terms of landform development and morphology because of its youth, state of seismic activity, and its recent deglaciation. These factors have combined to produce a unique fluvial landscape in that the fault-shattered metamorphic/igneous rocks of the range have been/are being eroded from their source cliffs at high rates which has covered the glacially scoured valley floors with colluvium such as talus slopes, rock slide, avalanche, and debris flow deposits. This project was focused on the characterization of all forms of mass movement, especially rock slides, multiple talus types (rockfall, alluvial, avalanche), protalus lobes, protalus ramparts, lobate and tongue-shaped rock glaciers, and their collective effects on water retention and its late-season delivery in the Grand Teton National Park, WY. A major goal of this project was to reclassify many of the mass movements in the park in an effort to streamline and simplify previous efforts by other scientists. Methods used during this study included field reconnaissance and measurements acquired during the summers of 2010 and 2013 and measurements taken from various datasets (NAIP imagery, shape files used within a GIS [ArcMap 10.0], and Google Earth™). Mass movement deposits, as well as ice glaciers and long-term snowbanks, were mapped and interpreted. Overall conclusions are that the major sources of mass movements from the Archean crystalline core of the range are the result of extensive jointing, fault-shattering, increased frost-wedging at higher altitudes, slopes steepened by prior glacial erosion, and extensive snow avalanches. Areas of Paleozoic sedimentary rocks marginal to the crystalline core produce rockslides as a result of steep dips and unstable shales beneath massive overlying carbonates. The presence of internal ground ice enables development of protalus lobes, thicker rock-fragment flows, and thinner boulder streams. Such ground ice is likely to enhance late-season water delivery downstream unless climate warming and recurrent droughts become too extreme.
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Ventura-Roca, J. « Distribución espacial y temporal de glaciares, glaciares cubiertos y glaciares rocosos durante la última deglaciación en el valle de La Bonaigua (Pirineo Central) ». Cuadernos de Investigación Geográfica 46, no 2 (15 septembre 2020) : 413–46. http://dx.doi.org/10.18172/cig.4395.

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The application of the paleogeographic method to the study of glacial landforms and rock glaciers allows their morphometric and sedimentological characterization, the establishment of a detailed morphostratigraphic sequence and a chronological proposal for the identified glacial phases. This study analyzes 86 landforms (57 glacial deposits, 21 rock glaciers and 8 protalus ramparts) in the Bonaigua Valley (Noguera Pallaresa Basin, Central Pyrenees), with special attention to the differentiation between debris-covered glaciers and rock glaciers. Other subjects studied concerning rock glaciers are: distinguish its glacial or periglacial origin; the possible current activity of some landforms, and the detection of rock glaciers located at low altitudes (in the current forest environment) through the use of high-resolution digital elevation model (2x2 m) from LIDAR data. The chronological hypothesis elaborated by correlation with other high Pyrenean valleys (with absolute ages available) includes 7 phases (6 glacial phases and 1 periglacial phase) in which co-exist and/or evolve, in a paraglacial dynamic, glaciers, debris-covered glaciers and rock glaciers, and that we temporarily place between the end of the Oldest Dryas and the Little Ice Age.
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Lewis, Colin A. « Protalus Ramparts and the Altitude of the Local Equilibrium Line during the Last Glacial Stage in Bokspruit, East Cape Drakensberg, South Africa ». Geografiska Annaler. Series A, Physical Geography 76, no 1/2 (1994) : 37. http://dx.doi.org/10.2307/521318.

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Lewis, Colin A. « Protalus Ramparts and the Altitude of the Local Equilibrium Line During the Last Glacial Stage in Bokspruit, East Cape Drakensberg, South Africa ». Geografiska Annaler : Series A, Physical Geography 76, no 1-2 (avril 1994) : 37–48. http://dx.doi.org/10.1080/04353676.1994.11880404.

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WATANABE, Teiji. « Re-examination of the "Protalus Ramparts" in the Navajo Glacier Area, Colorado Front Range, U.S.A., and Reconstruction of the Navajo Glacier in the Late Pleistocene/Holocene Stades. » Journal of Geography (Chigaku Zasshi) 102, no 1 (1993) : 60–72. http://dx.doi.org/10.5026/jgeography.102.60.

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Buckel, Johannes, Eike Reinosch, Andreas Hördt, Fan Zhang, Björn Riedel, Markus Gerke, Antje Schwalb et Roland Mäusbacher. « Insights into a remote cryosphere : a multi-method approach to assess permafrost occurrence at the Qugaqie basin, western Nyainqêntanglha Range, Tibetan Plateau ». Cryosphere 15, no 1 (11 janvier 2021) : 149–68. http://dx.doi.org/10.5194/tc-15-149-2021.

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Abstract. Permafrost as a climate-sensitive parameter and its occurrence and distribution play an important role in the observation of global warming. However, field-based permafrost distribution data and information on the subsurface ice content in the large area of the southern mountainous Tibetan Plateau (TP) are very sparse. Existing models based on boreholes and remote sensing approaches suggest permafrost probabilities for most of the Tibetan mountain ranges. Field data to validate permafrost models are generally lacking because access to the mountain regions in extreme altitudes is limited. The study provides geomorphological and geophysical field data from a north-orientated high-altitude catchment in the western Nyainqêntanglha Range. A multi-method approach combines (A) geomorphological mapping, (B) electrical resistivity tomography (ERT) to identify subsurface ice occurrence and (C) interferometric synthetic aperture radar (InSAR) analysis to derive multi-annual creeping rates. The combination of the resulting data allows an assessment of the lower occurrence of permafrost in a range of 5350 and 5500 m above sea level (a.s.l.) in the Qugaqie basin. Periglacial landforms such as rock glaciers and protalus ramparts are located in the periglacial zone from 5300–5600 m a.s.l. The altitudinal periglacial landform distribution is supported by ERT data detecting ice-rich permafrost in a rock glacier at 5500 m a.s.l. and ice lenses around the rock glacier (5450 m a.s.l.). The highest multiannual creeping rates up to 150 mm yr−1 are typically observed on these rock glaciers. This study closes the gap of unknown state of periglacial features and potential permafrost occurrence in a high-elevated basin in the western Nyainqêntanglha Range (Tibetan Plateau).
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Buckel, Johannes, Eike Reinosch, Andreas Hördt, Fan Zhang, Björn Riedel, Markus Gerke, Antje Schwalb et Roland Mäusbacher. « Insights into a remote cryosphere : a multi-method approach to assess permafrost occurrence at the Qugaqie basin, western Nyainqêntanglha Range, Tibetan Plateau ». Cryosphere 15, no 1 (11 janvier 2021) : 149–68. http://dx.doi.org/10.5194/tc-15-149-2021.

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Abstract. Permafrost as a climate-sensitive parameter and its occurrence and distribution play an important role in the observation of global warming. However, field-based permafrost distribution data and information on the subsurface ice content in the large area of the southern mountainous Tibetan Plateau (TP) are very sparse. Existing models based on boreholes and remote sensing approaches suggest permafrost probabilities for most of the Tibetan mountain ranges. Field data to validate permafrost models are generally lacking because access to the mountain regions in extreme altitudes is limited. The study provides geomorphological and geophysical field data from a north-orientated high-altitude catchment in the western Nyainqêntanglha Range. A multi-method approach combines (A) geomorphological mapping, (B) electrical resistivity tomography (ERT) to identify subsurface ice occurrence and (C) interferometric synthetic aperture radar (InSAR) analysis to derive multi-annual creeping rates. The combination of the resulting data allows an assessment of the lower occurrence of permafrost in a range of 5350 and 5500 m above sea level (a.s.l.) in the Qugaqie basin. Periglacial landforms such as rock glaciers and protalus ramparts are located in the periglacial zone from 5300–5600 m a.s.l. The altitudinal periglacial landform distribution is supported by ERT data detecting ice-rich permafrost in a rock glacier at 5500 m a.s.l. and ice lenses around the rock glacier (5450 m a.s.l.). The highest multiannual creeping rates up to 150 mm yr−1 are typically observed on these rock glaciers. This study closes the gap of unknown state of periglacial features and potential permafrost occurrence in a high-elevated basin in the western Nyainqêntanglha Range (Tibetan Plateau).
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Reinosch, Eike, Johannes Buckel, Jie Dong, Markus Gerke, Jussi Baade et Björn Riedel. « InSAR time series analysis of seasonal surface displacement dynamics on the Tibetan Plateau ». Cryosphere 14, no 5 (26 mai 2020) : 1633–50. http://dx.doi.org/10.5194/tc-14-1633-2020.

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Abstract. Climate change and the associated rise in air temperature have affected the Tibetan Plateau to a significantly stronger degree than the global average over the past decades. This has caused deglaciation, increased precipitation and permafrost degradation. The latter in particular is associated with increased slope instability and an increase in mass-wasting processes, which pose a danger to infrastructure in the vicinity. Interferometric synthetic aperture radar (InSAR) analysis is well suited to study the displacement patterns driven by permafrost processes, as they are on the order of millimeters to decimeters. The Nyainqêntanglha range on the Tibetan Plateau lacks high vegetation and features relatively thin snow cover in winter, allowing for continuous monitoring of those displacements throughout the year. The short revisit time of the Sentinel-1 constellation further reduces the risk of temporal decorrelation, making it possible to produce surface displacement models with good spatial coverage. We created three different surface displacement models to study heave and subsidence in the valleys, seasonally accelerated sliding and linear creep on the slopes. Flat regions at Nam Co are mostly stable on a multiannual scale but some experience subsidence. We observe a clear cycle of heave and subsidence in the valleys, where freezing of the active layer followed by subsequent thawing cause a vertical oscillation of the ground of up to a few centimeters, especially near streams and other water bodies. Most slopes of the area are unstable, with velocities of 8 to 17 mm yr−1. During the summer months surface displacement velocities more than double on most unstable slopes due to freeze–thaw processes driven by higher temperatures and increased precipitation. Specific landforms, most of which have been identified as rock glaciers, protalus ramparts or frozen moraines, reach velocities of up to 18 cm yr−1. Their movement shows little seasonal variation but a linear pattern indicating that their displacement is predominantly gravity-driven.
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Forte, Ana Paula, Cristian Daniel Villarroel et María Yanina Esper Angillieri. « Rock glacier and protalus rampart inventory in Las Salinas river basin, Central Andes of Argentina ». Cuadernos de Investigación Geográfica, 12 avril 2021. http://dx.doi.org/10.18172/cig.4922.

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This paper presents a detailed rock glacier and protalus rampart inventory from Las Salinas river basin, an arid subtropical mountain hydrological system (between 31°02’ and 31°22’ S latitude) located in the northern sector of the Central Andes of Argentina, where permafrost and cryogenic processes prevail. The inventory is based on a geomorphological characterization by means of optical remote sensing and field description data. The study region covers 630 km2, with 3.25% of the area containing 405±8.2 rock glaciers and protalus ramparts in total, of which 231±2.5 are considered protalus rampart and 49±2 are considered active, 61±1 inactive and 64±3 fossil rock glaciers. Frequency ratio and logistic regression were used as statistical methods to determine the relationship between the distribution of these periglacial landforms and different geological, morphometric and climatic variables as elevation, potential incoming solar radiation, slope, aspect and lithology. Results show that elevation, lithology, and aspect are the most influencing factors for the occurrence of active rock glaciers. According to rock glaciers and protalus ramparts distribution, the permafrost occurrence probability is above 3690 m a.s.l. (current and high periglacial environment). However, some inactive rock glaciers and protalus rampart were found below this elevation, thus between 3300 and 3690 m a.s.l. the landscapes are dominated by an unstable periglacial environment.
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Anderson, Edward, Stephan Harrison et David Passmore. « A Late-glacial protalus rampart in Macgillycuddy's Reeks, south-west Ireland ». Irish Journal of Earth Sciences 37, no 1 (2019). http://dx.doi.org/10.1353/ijes.2019.0014.

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Anderson, Harrison et Passmore. « A Late-glacial protalus rampart in Macgillycuddy's Reeks, south-west Ireland ». Irish Journal of Earth Sciences, 2019. http://dx.doi.org/10.3318/irisjeartscie.2019.06.

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Pecker Marcosig, Ivanna, et Dario Trombotto Liaudat. « Análisis de la dinámica de dos mallines de altura en Vallecitos, Cordón del Plata, Mendoza, Argentina en el periodo 2002-2019 ». Acta Geológica Lilloana, 13 avril 2021, 1–24. http://dx.doi.org/10.30550/j.agl/2021.33.1/2021-02-18.

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El área de estudio se encuentra ubicada en el Cordón del Plata, Cordillera Frontal, Mendoza, Argentina correspondiendo geográficamente entre los meridianos 69 º 19' y 69 º 26' O y los paralelos 32 º 55' y 32 º 59' S. Aquí encontramos alturas máximas de 6000 msnm con presencia de glaciares y manchones de hielo perenne, sin embargo, el ambiente predominante es periglacial con predominancia de glaciares de escombros, protalus ramparts y superficies de soli y gelifluxión. Sumado a ello se pueden encontrar mallines a alturas superiores a 3000 msnm. El objetivo del presente trabajo es analizar la dinámica producida en dos mallines de altura anualmente frecuentados durante el periodo 2002 - 2019 como bioindicadores de cambios a nivel térmico y humedad a fin de conocer los procesos que pueden estar afectando a los mallines en particular y al ambiente en general. La metodología utilizada se basa en el uso de imágenes de satélite para la clasificación, digitalización de márgenes de las vegas y construcción de índices (NDVI, NWDI), usos de datos meteorológicos del área de estudio e información relevada en campo en sucesivos inventarios de las geoformas presentes.
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