Processi paraglaciali su alcuni versanti alpini: i casi di studio della Valle di Slingia (Bz), del Ghiacciaio di Cima Uomo (Tn) e del Bacino del Vauz (Bl).

This PhD thesis has been carried out in the context of a Strategic Project of the University of Padua ("Georisk"), which aim was the study of the geological and hydrological hazards in the north-east of Italy. The project was divided into 5 workpackages (WP) and the PhD study was mainly conducted in the framework of WP1 ("slope processes"). The study focused on the geomorphological evolution of three mountain areas affected by the presence of glaciers at different times. According to the literature, after the glacial mass withdrawal the evolution of these territories is defined "paraglacial evolution". In particular, the study areas are: the Schlinig Valley (Eastern Alps - South Tyrol), the area of Cima Uomo Glacier (Dolomites - Trentino) and the Vauz Basin (Dolomites - Belluno). In the Schlinig Valley the aim was to assess the state of the slopes which are affected by various DSGSDS (Deep Seated Gravitational Slope Deformations). At Cima Uomo the purpose was to understand how the permafrost presence can drive the evolution of the area during and after the deglaciation. Finally, in the Vauz Basin, the aim was to understand the present evolution of this area, which in the past underwent paraglacial modeling processes and modification, as documented by some relict landforms. The detailed study of the three investigated areas allowed to: 1) characterize the current geomorphological processes, 2) understand the past morphological evolution and 3) better understand the developmental status achieved in each area with respect to the paraglacial period. The three study areas highlight the importance of the local topo-climatic factors on the characteristics of paraglacial evolution processes, deposits and landforms respect to the wider scale climatic factors

Pre-Alpine and Alpine deformation at San Pellegrino pass (Dolomites, Italy)

In this work, we present the geological map of the San Pellegrino pass, inserted in the spectacular scenario of the Dolomiti region (Southern Alps, Italy), at a scale of 1:10.000 and accompanied by geological cross-sections. The detailed distinction of lithological thin units allowed to achieve a consistent interpretation of the local structural setting by drawing brittle and ductile Alpine tectonic deformations. The differential deformation and structural styles within the geological map are the result of the different rheological nature of volcanic and sedimentary rocks, as well as of the superimposition of compressional Alpine tectonics over Permo-Mesozoic extensional tectonic phases, and consequent reactivation of inherited structures

Modern air, englacial and permafrost temperatures at high altitude on Mt Ortles (3905 m a.s.l.), in the eastern European Alps

The climatic response of mountain permafrost and glaciers located in high-elevation mountain areas has major implications for the stability of mountain slopes and related geomorphological hazards, water storage and supply, and preservation of palaeoclimatic archives. Despite a good knowledge of physical processes that govern the climatic response of mountain permafrost and glaciers, there is a lack of observational datasets from summit areas. This represents a crucial gap in knowledge and a serious limit for model-based projections of future behaviour of permafrost and glaciers. A new observational dataset is available for the summit area of Mt Ortles, which is the highest summit of South Tyrol, Italy. This paper presents a series of air, englacial, soil surface and rock wall temperatures collected between 2010 and 2016. Details are provided regarding instrument types and characteristics, field methods, and data quality control and assessment. The obtained data series are available through an open data repository (https://doi.org/10.5281/zenodo.8330289, Carturan et al., 2023). In the observed period, the mean annual air temperature at 3830 m a.s.l. was between −7.8 and −8.6 ∘C. The most shallow layers of snow and firn (down to a depth of about 10 m) froze during winter. However, melt water percolation restored isothermal conditions during the ablation season, and the entire firn layer was found at the melting pressure point. Glacier ice is cold, but only from about 30 m depth. Englacial temperature decreases with depth, reaching a minimum of almost −3 ∘C close to the bedrock, at 75 m depth. A small glacier located at 3470 m a.s.l., close to the summit of Mt Ortles, was also found in cold conditions down to a depth of 9.5 m. The mean annual ground surface temperature was negative for all but one monitored sites, indicating cold ground conditions and the existence of permafrost in nearly all debris-mantled slopes of the summit. Similarly, the mean annual rock wall temperature was negative at most monitored sites, except the lowest one at 3030 m a.s.l. This suggests that the rock faces of the summit are affected by permafrost at all exposures.</p

The Ortles ice cores: uncovering an extended climate archive from the Eastern Alps

During the last half century, oxygen and hydrogen stable isotope content of ice cores has been extensively used for air temperature reconstructions. The most suitable glaciers of the Alpine area, most exclusively in the Western Alps, havebeen utilizedfor icecoring formore thanfour decades.The paleoclimatic potential of theEastern Alps isstilllargelyunexploitedandwasscarcelyutilizedinthepastmainlybecauseofthelowerelevation(comparedto Western Alps) and hence the difficulty to find glaciers in cold conditions. The warming temperature trend appears to be particularly pronounced in the Alps, threatening the preservation of the glaciated areas and creating a sense of urgency in retrieving climatic archives before it is too late. In autumn 2011, four deep cores were drilled on Mt Ortles, South Tyrol, Italy, at 3859 m a.s.l. An extensive reconstructed temperature record for the Ortles summit, based on the surrounding meteorological station data, is available for the last 150 years, while an automatic weather station had been operating from 2011 to 2015 in proximity of the drilling site. The new ice core chronology, based on 210Pb, tritium, beta emissions analysis and 14C measurements of the particulate organic carbon, indicates that the bottom ice is 7000 years old, making it the second most extended glaciological archive ever retrieved in the Alps. The three equally long ice cores have been analyzed for oxygen and hydrogen stable isotopes throughout their length, and the goal is to create an Ortles stacked record for d18O and dD and compare the isotopic data to instrumental temperatures and to other Alpine records. Since 2008, several snow pits were dug in proximity of the drilling site during summer, when the temperature can oftenexceedthemeltingpoint.Theisotopicprofilesofthe2015snowpit,dugattheendofanexceptionallywarm summer,showhowtheisotopesignalisnowaffectedbythepost-depositionalprocessesthathaveoccurredduring that summer

Age of the Mt. Ortles ice cores, the Tyrolean Iceman and glaciation of the highest summit of South Tyrol since the Northern Hemisphere Climatic Optimum

In 2011 four ice cores were extracted from the summit of Alto dell'Ortles (3859 m), the highest glacier of South Tyrol in the Italian Alps. This drilling site is located only 37 km southwest from where the Tyrolean Iceman, similar to 5.3 kyrs old, was discovered emerging from the ablating ice field of Tisenjoch (3210 m, near the Italian-Austrian border) in 1991. The excellent preservation of this mummy suggested that the Tyrolean Iceman was continuously embedded in prehistoric ice and that additional ancient ice was likely preserved elsewhere in South Tyrol. Dating of the ice cores from Alto dell'Ortles based on Pb-210, tritium, beta activity and C-14 determinations, combined with an empirical model (COPRA), provides evidence for a chronologically ordered ice stratigraphy from the modern glacier surface down to the bottom ice layers with an age of similar to 7 kyrs, which confirms the hypothesis. Our results indicate that the drilling site has continuously been glaciated on frozen bedrock since similar to 7 kyrs BP. Absence of older ice on the highest glacier of South Tyrol is consistent with the removal of basal ice from bedrock during the Northern Hemisphere Climatic Optimum (6-9 kyrs BP), the warmest interval in the European Alps during the Holocene. Borehole inclinometric measurements of the current glacier flow combined with surface ground penetration radar (GPR) measurements indicate that, due to the sustained atmospheric warming since the 1980s, an acceleration of the glacier Alto dell'Ortles flow has just recently begun. Given the stratigraphic-chronological continuity of the Mt. Ortles cores over millennia, it can be argued that this behaviour has been unprecedented at this location since the Northern Hemisphere Climatic Optimum

Processi paraglaciali su alcuni versanti alpini: i casi di studio della Valle di Slingia (Bz), del Ghiacciaio di Cima Uomo (Tn) e del Bacino del Vauz (Bl).

This PhD thesis has been carried out in the context of a Strategic Project of the University of Padua ("Georisk"), which aim was the study of the geological and hydrological hazards in the north-east of Italy. The project was divided into 5 workpackages (WP) and the PhD study was mainly conducted in the framework of WP1 ("slope processes"). The study focused on the geomorphological evolution of three mountain areas affected by the presence of glaciers at different times. According to the literature, after the glacial mass withdrawal the evolution of these territories is defined "paraglacial evolution". In particular, the study areas are: the Schlinig Valley (Eastern Alps - South Tyrol), the area of Cima Uomo Glacier (Dolomites - Trentino) and the Vauz Basin (Dolomites - Belluno). In the Schlinig Valley the aim was to assess the state of the slopes which are affected by various DSGSDS (Deep Seated Gravitational Slope Deformations). At Cima Uomo the purpose was to understand how the permafrost presence can drive the evolution of the area during and after the deglaciation. Finally, in the Vauz Basin, the aim was to understand the present evolution of this area, which in the past underwent paraglacial modeling processes and modification, as documented by some relict landforms. The detailed study of the three investigated areas allowed to: 1) characterize the current geomorphological processes, 2) understand the past morphological evolution and 3) better understand the developmental status achieved in each area with respect to the paraglacial period. The three study areas highlight the importance of the local topo-climatic factors on the characteristics of paraglacial evolution processes, deposits and landforms respect to the wider scale climatic factors.La presente tesi di Dottorato è stata realizzata nell’ambito di un Progetto Strategico dell’Università degli Studi di Padova (“Georisk”), il quale aveva come obiettivo lo studio dei rischi geologici e idrologici nell’Italia nord orientale. Il Progetto strategico era articolato in 5 Workpackages (WP) e al loro interno hanno operato in sinergia altrettante Unità Operative. Il presente studio è stato condotto nell’ambito del WP1 “processi di versante” ed è stato rivolto particolarmente all’analisi dell’evoluzione geomorfologica di aree montane. La ricerca di dottorato, dovendosi inserire in un progetto di ricerca più ampio, ha preso in considerazione aree di studio che fossero anche di interesse per le altre unità. In particolare le aree studiate sono tre: la Valle di Slingia (Alpi Orientali – Alto Adige), il Ghiacciaio di Cima Uomo (Dolomiti – Trentino), il Bacino del Vauz (Dolomiti – Belluno). Le aree prese in considerazione sono state, in tempi diversi, interessate dalla presenza dei ghiacciai. Attualmente, solo una di queste è ancora in una certa relazione con il glacialismo. Di conseguenza, l’evoluzione che questi territori hanno avuto dopo il ritiro delle masse glaciali è avvenuta secondo quanto in letteratura è definito come “morfogenesi paraglaciale”. Nella Valle di Slingia lo scopo è stato quello di valutare lo stato di versanti interessati da varie DGPV (Deformazioni Gravitative Profonde di Versante). Al Ghiacciaio di Cima Uomo lo scopo del lavoro è stato quello di comprendere come la presenza di permafrost può controllare l’evoluzione di un’area in fase di deglacializzazione. Infine nel Bacino del Vauz l’obbiettivo è stato quello di capire l’evoluzione che interessa attualmente un’area che in passato ha subito processi di modellamento e modificazione strettamente paraglaciali come documentato da alcune forme relitte. Lo studio dettagliato delle tre aree indagate ha permesso, oltre ad una caratterizzazione da vari punti di vista dei processi in atto e dell’evoluzione morfologica passata, di comprendere meglio lo stato evolutivo raggiunto in ciscun’area, in termini di riassetto paraglaciale del sistema (periodo paraglaciale). In conclusione ciò che è emerso, analizzando le tre aree studiate, è l’importanza che assumono i fattori di tipo topo-climatico locali nel condizionare tipologie, caratteristiche evolutive dei processi, depositi e forme paraglaciali rispetto ai fattori climatici che agiscono a più ampia scala

GROUND TEMPERATURE REGIMES OF A DOLOMITIC AREACHARACTERIZED BY CRYOGENIC LANDFORMS.

The studied area corresponds to the so-called Basin of Vauz, located between 1840 m and 2250 m of elevation. It lies between the Pordoi Pass (Dolomites) and the village of Arabba (BL). There are several landforms related to frost action and solifluction in this area, such as patterned ground, terracettes and lobes. This research aims at i) studying the processes involved in the slow movement of the ground and in the development of the landforms of the area, and ii) understanding the role of water circulation inside the slope. Analogous phenomena are present in many areas of the Dolomites, especially on the passes and in several locations where pelitic and volcano-clastic formations crop out (i.e. S. Cassiano Fm. and Wengen Fm.). Indeed, the movements usually develop within the detrital deposits generated from the degradation of the two previously mentioned geological formations. The particle sizes of debris involved in the movements are between coarse sand and fine silt, with a predominance of medium sand and coarse silt (from 4mm to 0,002mm). Measurements of the thermal state of the soil were recently undertaken in the study area, using thermometric probes (PB-5001-1M5; accuracy \ub10.2\ub0C) connected to specific data loggers (TGP-4520 TINYTAG PLUS 2). They allow to store hourly minimum, maximum and average temperature. Measurements were collected at 1874 m, 1935 m, 2190 m and 2365 m of altitude, at sites exposed to the south and with an inclination of respectively 23 \ub0, 14 \ub0, 11 \ub0 and 36 \ub0. In order to analyze the trend of temperature with depth, in one of the monitoring sites (at 1935 m) three thermometers were placed at different depth (5 cm, 25 cm and 50 cm from the ground level). Data on air temperatures and snow thickness are provided by the weather stations of Arabba and Passo Pordoi - Belvedere (data supplied by the ARPAV Meteorological Centre of Arabba and Meteotrentino). Data series between November 2009 and September 2010 have been already collected, while a second set of data spanning from autumn 2010 to spring 2011 are going to be collected. The first data show that in autumn 2009, in absence of snow cover, soil temperatures fluctuated in connection the daily air temperature cycles but the ground temperature remained above 0\ub0C. After the first snowfall, this connection weakened and the ground temperatures developed independently from the air temperature variations. The soil temperatures at the various monitoring sites reached stable values above 0\ub0C during winter, until the snow cover disappeared. Thermometers placed at different depths show an attenuation of the thermal wave with increasing depth. The thermal cycles are visible at a depth of 5 cm, while at 25 cm depth they are more attenuated (only when snow cover is absent, e.g. autumn and late spring). Moreover, higher temperatures were recorded at 50 cm than at 5 cm and at 25 cm in autumn and in winter, the opposite in spring and in summer. During winter, with the presence of snow cover, generally an almost stable value of temperature is reached at every depth without temperature oscillations. The collected temperatures indicate the absence of freeze conditions during the full year at all the monitoring sites. Actually, soil temperatures never fell below 0\ub0C, even if air temperatures reached values well below 0\ub0 C (- 15\ub0, -18\ub0 C). The lowest temperatures are not recorded at the highest monitoring sites, indicating that not only the altitude but also the steepness and the exposure of the slopes exert a strong control on the thermal regime of the soil. The results obtained so far suggest that the thermal regime of the ground controls in a complicated way the solifluction phenomena affecting the slopes of this area

Deep Seated Gravitational Slope Deformations geomorphometry. The case of Schlinig valley (Eastern Alps)

The Alpine regions are widely affected by slope instability, determined by various interactions between climate and local geological framework. Our research focuses on Deep Seated Gravitational Slope Deformations (DSGSDs), which are large mass movements with low rates of displacement (some mm/years) and involving wide portions of hillslopes with medium to high-relief slopes energy (> 500 m). They may occur on all rock types although are more common on highly foliated metamorphic lithologies. Although DSGSDs are characterized by specific landforms, the most distinctive ones being double ridges, scarps, counterscarps, trenches, these morphostructures can be classified in between landslides and tectonic landforms. In addition, depending on their stage of evolution and typology, DSGSDs can be masked by weathering and superficial erosion processes and the typical bulging at the hillslope foot of large mass movements can be not always present. For these reasons ready methodologies to unravel morphostructures related to DSGSDs are important and needed. Thus, we present procedures based on the calculation of morphometric indices from LiDAR-DEM, with the aim to improve the DSGSDs geomorphological identification and mapping. Our work has been focused on the Schlinig valley (Eastern Alps, South Tyrol) because it is affected by numerous DSGSDs types, evolving on various lithologies, which are in tectonic contact along a major alpine fault (Schlinig fault). In particular, the orthogneiss of the Scharl nappe crop out in the right side of the valley, whereas in the left-hand slope the Permo-Mesozoic cover of the same nappe are overlaid by the 6tztal paragneisses