The response of glacial masses to climate change is well documented. However, the impact of landslides on glacier dynamics and stability requires greater research. Landslides in glacierized mountains can be caused by climate change (e.g. permafrost thawing), intense precipitation, paraglacial response of slopes or earthquakes and can, in turn, limit ablation, increase meltwater production and alter glacier velocities. Besides, landslides can be hazardous to life and infrastructure. Permafrost degradation, de-buttressing of slopes, extreme precipitation and freezing and thawing cycles make mountain glaciers susceptible to instability and cascading hazards. Our project thus focuses on identifying the research gaps associated with landslide-glacier dynamics and related hazards. The two components of our project are 1) Remote sensing and GIS and 2) Modelling. Different spatial scales (landform, catchment, global) will be considered for our research.

This presentation aims to outline PhD project and discuss proposed approaches with the glaciological, geomorphological, and remote sensing community. A literature review aimed at generating an inventory of landslide-affected glaciers globally is the first step. This will be complemented by detailed analyses and quantification of landslide-induced changes in glaciers’ behaviour by selecting benchmark case studies across different glacial systems representing different environmental conditions. Acquiring UAV data (0.05-0.10 m), high resolution (0.3-1.0 m) (Pleiades, WorldView, etc.), and medium resolution (10-50 m) satellite imagery (Landsat, Sentinel, Aster) will be essential for the quantification of changes in glaciers velocity and mass balance. We also plan field visits to benchmark glaciers to ground-truth remote sensing data and collect information about sedimentological and geomorphological characteristics of landslide deposits.

This research was funded by the National Science Centre, Poland, project number 2021/42/E/ST10/00186

How to cite: Bhattacharyya, A., Ewertowski, M., Małecki, J., and Domej, G.: Quantification of landslide-induced changes in glacier dynamics – project outline, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3491, https://doi.org/10.5194/egusphere-egu24-3491, 2024.

This study presents the first palaeoglacial assessment of the mountainous terrain in the western region of the Putorana Nature Reserve, Russian Federation. This exploration, the first of its kind in this region, focuses on approximately 200 cirques, utilising cirque floor altitudes as a proxy for Equilibrium Line Altitudes (ELAs) as a pivotal palaeoclimate indicator. The primary objective is to gain unprecedented insights into the last glacial advancement in the area and to contribute to our understanding of the palaeoclimate during the potential Last Glacial Maximum (LGM) in Russia.

Employing the Ohmura equation, this research aims to construct a comprehensive palaeo climate profile, with ELAs estimated from cirque floor altitudes. These cirques are systematically mapped using the 10 m Arctic DEM and reconstructed using the GlaRe tool. Additionally, the physical parameters of the cirques will be rigorously evaluated using the newly developed ACME2.0 tool. By concentrating on the last glacial advancement, this study seeks to provide valuable information about the palaeoclimatic conditions and glacial dynamics within the Western Putorana Nature Reserve. This offers the first insights into the understanding of the mountain glacial history of the region.

How to cite: Lee, E. and Oien, R.: Insights from Cirque Floor Altitudes in the Western Putorana Nature Reserve, Russian Federation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3632, https://doi.org/10.5194/egusphere-egu24-3632, 2024.

Knowledge of subglacial conditions is of great relevance in understanding glacier dynamics. A combination of micro- and macrosedimentological analysis of diamictons and deformation structures can form the basis for the reconstruction of past subglacial conditions. We present the results of such a study on subglacial tills, within an Alpine environment, at Einödgraben in the Kitzbühel Alps (Tyrol/Austria). The Late Pleistocene succession there (MIS 5d-MIS 2) shows great diversity in facies from wood-bearing alluvial to glaciolacustrine to subglacial deposits. Two glaciogenic diamictons (tills) within the sequence were analysed at the microscale and are correlated to the Last Glacial Maximum (LGM; Würmian Pleniglacial) and the early Lateglacial phase of ice decay. The first deformation phase of pre-LGM deposits occurred most likely in a subglacial setting close to the advancing glacier margin and resulted in diapir-like glaciotectonic macro-structures, which are unique for an inneralpine area. Subglacial erosion over these structures occurred and later pre-LGM emplaced deposits underwent deformation and partial homogenisation immediately beneath the glacier base leading to diamictons, indicative of subglacial deformable bed conditions. The tills of the LGM and the Würmian Lateglacial show a range of microfacies and deformation structures evidence of close and rapid changes in till rheology and stress field dynamic in the subglacial environment. Our study demonstrates the need for a reinvestigation of deposits occurring in the proximity of past active ice interfaces. The paleoglaciological evidence assembled from the detailed and spatially close research on the microsedimentology of till at Einödgraben reflects our increasing comprehension and understanding of till microsedimentology in Alpine environments. An awareness is also shown of the need for much further research on the glacial depositional mechanics in mountainous terrains that are different from those in the immense lowland plains of the extensive paleo-ice sheets of North America and Northern Europe.

How to cite: Reitner, J. M. and Menzies, J.: Till formation and subglacial deformation in a stratigraphic complex Late Pleistocene sequence (Einödgraben / Aurach, Kitzbühel Alps, Austria), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4566, https://doi.org/10.5194/egusphere-egu24-4566, 2024.

Marine geophysical data combined with radiocarbon dated sediment cores provide a record of the advance and retreat of the ancestral Northeast Greenland Ice Stream (NEGIS) across the continental shelf offshore of NE Greenland during the last glaciation. Today, NEGIS is the largest ice stream to drain the Greenland Ice Sheet (GrIS), holding a sea-level equivalent of 1.1-1.4 m. However, the longer-term history of the ice stream, especially on the adjoining outer continental shelf has, to date, been poorly constrained. Streamlined subglacial landforms record grounded ice flow in the outer shelf section in cross shelf bathymetric troughs, with mega-scale glacial lineations recording former streaming flow towards the shelf edge. Flow transverse landforms in the form of downlow-tapering, sediment wedges occur at the shelf edge and on the outer-mid shelf of the bathymetric troughs. These landforms differ in their morphology from the classic ‘ramp-step’ form of typical grounding wedges but are similarly interpreted as a form of grounding-zone wedge in which sediment prograded and thinned away from the grounding-zone. The wedges record a shelf-edge terminating, grounded ancestral NEGIS, as well as the subsequent episodic retreat of the ice stream inshore during deglaciation. Beyond the shelf edge, glacigenic debris flows imaged on acoustic stratigraphic profiles and recovered in sediment cores document sediment delivery onto the slope; such deposits are typical of submarine slopes offshore of shelf-edge terminating palaeo-ice streams. On the outer shelf subglacial tills and grounding-zone proximal sediments overlain by deglacial stratified glacimarine sediments record ice stream advance and retreat in the troughs. Radiocarbon dates from glacimarine sediments in these cores indicate early deglaciation from the shelf edge but with relatively slow rates of subsequent ice-stream retreat across the outer shelf.

How to cite: O'Cofaigh, C., Roberts, D., Callard, S. L., Lloyd, J., Ware, G., Streuff, K., Jamieson, S., Dorschel, B., and Kanzow, T.: Geomorphological and sedimentological records of Greenland Ice Sheet advance and retreat on the continental shelf offshore of NE Greenland during the last glaciation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6551, https://doi.org/10.5194/egusphere-egu24-6551, 2024.

Latest advances in numerical modelling using machine learning sped-up glacier models by several orders of magnitude, thus facilitating glacier evolution models to run at high resolutions (hundreds of metres) over timescales of several tens of millennia and over mountain range scales. The RECONCILE project seeks to use the Instructed Glacier Model (IGM) to simulate the maximum state and deglaciation of the last glaciation of the European Alps and to test model output against the geological record. A robust framework against which to test Alps-wide and transient paleoglacier model simulations is however missing. Despite the long history of Quaternary research in the Alps and abundant publications on the topic, the integration of field evidence for model validation has thus far largely been restricted to the Last Glacial Maximum (LGM) ice extent. Inspired by work on the (former) British, Fennoscandian, Patagonian and Greenland ice sheets, we aim to build a comprehensive and standardized dataset on paleoglacier variations for the European Alps. Coupling geo(morpho)logical data and geochronological markers, the AlpIce database will act as an empirical basis for future quantitative model-data comparisons. Published empirical evidence that restrains the build-up, culmination, and disintegration of the Alpine LGM glaciers as well as subsequent Alpine Lateglacial and Holocene glacier advances are considered. Relevant surface exposure and radiocarbon datings are currently gathered and fed into the database. Data reliability assessments and paleoglaciological context classifications are undertaken concurrently. The database structure also allows the inclusion of additional chronological methods (e.g. luminescence dating, dendrochronology, archeological and historical sources) into AlpIce. Where applicable, the chronological constraints will be linked to related geo(morpho)logical features (e.g. former ice margins, trimlines) using GIS software. AlpIce is designed as an open-access resource hoping to prove useful for both empirical and modelling communities and beyond the scope of model validation.

How to cite: Kamleitner, S., Leger, T. P. M., Ivy-Ochs, S., Nussbaumer, S. U., Vieli, A., and Jouvet, G.: AlpIce - Towards an Alps-wide database of empirical geo(morpho)logical and geochronological data constraining Last Glacial Maximum to Holocene glacier fluctuations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9282, https://doi.org/10.5194/egusphere-egu24-9282, 2024.

The glacial hydrology and stability to sliding episodes of the Greenland Ice Sheet (GIS) are closely linked to the subglacial drainage capacity of its bed, which depends on its structure and connectivity. The central-western portion of the GIS, specifically in the region around Kangerlussuaq, is characterized by subglacial drainage systems consisting on meltwater-filled cavities on a hard bed (Harper et al., 2017), which may become interconnected following episodes of increased discharge. Episodes of connectivity following high pressure subglacial meltwater events may lead to enhanced sliding followed by channelization, and emplacement of subglacial floods (Harper et al., 2017).

We present preliminary field and remote sensing observations describing the morphology, topology, organization, and other field characteristics of recently exposed elements of the glacial hydrology system, which were emplaced by the western margin of the GIS. Our field site is located by the Europlanet Transnational Access TA1 Facility 4: Greenland-Kangerlussaq, which offers a unique opportunity to study the subglacial drainage patterns in this region (Carrivick et al., 2016). Few regions in the world offer the opportunity to study recently emplaced, well exposed subglacial morphologies at the level of accessibility of this site. Field data includes in situ-imagery, observations of glacial sliding directions, description of sedimentary deposits, morphology, scale and characteristics of subglacial cavities, and nature of the connection passages. Data acquired in the field is complimented with remote sensing data from the ArcticDEM and Maxar imagery.

We conclude with a discussion of the implications of our observations for the geometry and volumetric capabilities of currently active subglacial hydrology pathways under the western portion of the GIS, including addressing the possible modes of meltwater drainage from the observed morphologies and subglacial geological reconstructions (e.g., White et al., 2016), as well as a comparison of the morphology and geometry of observed interconnected subglacial cavities to morphologically and topologically similar systems located at the east of Hellas Basin on Mars. 

How to cite: Grau Galofre, A. and Noblet, A.: Field observations of interlinked subglacial cavities in Kangerlussuaq - Greenland ice sheet western margin., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10169, https://doi.org/10.5194/egusphere-egu24-10169, 2024.

This study employs Arctic DEM data and GIS tools, ACME 2.0 (Li et al., 2024), and GlaRe (Pellietero et al., 2016), to systematically investigate cirques in the western islands off central Greenland. The primary objective is to reconstruct past Equilibrium Line Altitude (ELA) variations at the end of the Younger Dryas period and derive insights into palaeoclimate conditions in this region.

By leveraging high-resolution Arctic DEM datasets and advanced GIS methodologies, we analyse cirque morphologies and elevations to reconstruct ELAs, a key indicator of glacial development and climate conditions. The Younger Dryas, a well-documented, abrupt and relatively short climatic event, represents a critical period for understanding past climate dynamics and their impact on glacial landscapes on a timescale relevant to the contemporary human population.

Our approach combines the semi-automated extraction of cirque parameters from the Arctic DEM with GIS-based modelling to reconstruct palaeo-ELA variations. Through spatial and temporal analysis, we aim to discern patterns of glacial response to climatic shifts between 13-9.5ka (Leger et al., 2024), shedding light on the sensitivity of Arctic cirques to rapid environmental changes.

Preliminary results indicate distinct patterns in cirque morphology and ELAs consistent with variations in the ELA during the Younger Dryas. These findings contribute to a more comprehensive understanding of the regional impact of past climatic events on the Greenlandic glacial landscape. This research enhances our knowledge of the Younger Dryas climate dynamics in the western islands off Greenland, providing valuable insights into the region's palaeoclimate history and contributing to broader discussions on Arctic environmental change.

How to cite: Oien, R. and Kurjanski, B.: Geomorphological Analysis of Cirques in the Western Islands of Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11858, https://doi.org/10.5194/egusphere-egu24-11858, 2024.

Significant mass loss and increased rock debris cover have been observed across many mountain glaciers due to climate change. However, the dynamics of sediment transport through alpine glaciers are not fully understood and should be investigated to better constrain the future evolution of mountain glaciers under a changing climate. Englacial sediment transport is difficult to observe and to that end, we quantify the englacial transport time of debris within a glacier using a novel method combining luminescence rock surface burial dating and ice-flow modelling. Our study focuses on Mer de Glace, Mont Blanc Massif, French Alps, where supraglacial debris has expanded over the past 20 years.

We collected near-surface rock debris (4–22 cm in diameter) of granite from the ablation area of Mer de Glace that we expect to have experienced different englacial transport durations. Under subdued red light, we cored the samples perpendicular to their surfaces and sliced the cores into ~1 mm discs for luminescence dating. We first evaluated whether the luminescence signals had been well bleached prior to deposition by measuring the evolution of luminescence signals with depth throughout the core (i.e. measurement of the bleaching plateau). We used a protocol comprising infra-red stimulation at 50 °C and 225 °C, followed by blue stimulation at 125 °C to explore the signals of different minerals with different luminescence properties. Of the 29 samples investigated, 20 were well bleached, exhibiting a clear plateau in luminescence signals with depth (following the approach of Rades et al., 2018). We are currently using a single-aliquot regenerative dose protocol to date the rock surfaces of these samples to obtain englacial transport durations. In the next step, we will contrast the englacial transport durations measured using luminescence with those predicted using the ice-flow model IGM (Jouvet et al., 2022), allowing us to better understand the dynamics of mountain glaciers over centennial to millennial time scales.

References

Jouvet, G., Cordonnier, G., Kim, B., Lüthi, M., Vieli, A., & Aschwanden, A. (2022). Deep learning speeds up ice flow modelling by several orders of magnitude. Journal of Glaciology, 68(270), 651-664.

Rades, E. F., Sohbati, R., Lüthgens, C., Jain, M., & Murray, A. S. (2018). First luminescence-depth profiles from boulders from moraine deposits: Insights into glaciation chronology and transport dynamics in Malta valley, Austria. Radiation Measurements, 120, 281-289.

How to cite: Rodari, L., Margirier, A., King, G., Rowan, A., Schmidt, C., and Jouvet, G.: Luminescence rock surface dating of englacial transported debris from Mer de Glace glacier, French Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11985, https://doi.org/10.5194/egusphere-egu24-11985, 2024.

The presence of cosmogenic radionuclide concentrations inherited from previous exposure(s) of glacially transported boulders and moulded bedrock surfaces may hinder the determination of the surface exposure age (SED) of the last phase of (de)glaciation.

A previous study revealed that glacial landforms of the cirque area in the southern side of the Retezat Mountains (Southern Carpathians, Romania) hold significant amount inherited ¹⁰Be (t_1/2=1.4 My), which was used for a tentative estimation of the amount of glacial erosion, assuming that the lowest ¹⁰Be concentration was representative of the true age of deglaciation (Ruszkiczay-Rüdiger et al., 2021, Geomorphology 384, 107719).

In this study, a western valley, the Zlătuia-Dobrunu valley of the Retezat Mts was sampled for ¹⁰Be SED. The novel data are in agreement with the previous datasets suggesting that the most extended glaciers belonged to the Last Glacial Maximum. However, the old apparent exposure durations based on ¹⁰Be analysis of samples from the cirque area provided firm evidence for the presence of excessive abundances of cosmogenic ¹⁰Be in this valley as well.

The use of the short-lived in situ produced ¹⁴C (t_1/2= 5.7 ky) provides an independent age constraint for the timing of the last deglaciation, because all ¹⁴C inventories that might be inherited from a previous exposure would have already been decayed. As a consequence, the ¹⁴C concentrations are not biased by inheritance, thus i) enable the age determination of the landforms belonging to the last phases of deglaciation and ii) the ¹⁴C exposure ages compared to the ¹⁰Be data will allow an assessment of the inherited amount of ¹⁰Be and thus a more precise determination of the amount of glacial erosion.

In this study the new ¹⁰Be and ¹⁴C SED ages will be presented together with the mapped glacial landforms, reconstructed paleoglaciers and their Equilibrium Line Altitudes.

Funding: NKFIH FK124807, INSU/CNRS, ANR - “EQUIPEX Investissement d’Avenir”, IRD and CEA, the PNRR-III-C9-2022 - I8, no. 760055/23.05.2023, CF 253/29.11.2022. and Horizon 2020 grant 871149 ”EUROPLANET”.

How to cite: Ruszkiczay-Rüdiger, Z., Kern, Z., Madarász, B., Urdea, P., Braucher, R., Molnár, M., Búró, B., and Team, A.: New surface exposure age data using cosmogenic radionuclides 10Be and 14C to constrain the age of the last deglaciation in the Retezat Mts, Southern Carpathians, Romania, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12758, https://doi.org/10.5194/egusphere-egu24-12758, 2024.

I present the first dataset of Late Quaternary glacial maximum extent and deglaciation along with quantitative paleoclimate reconstructions from the Ahuriri River valley, Southern Alps, New Zealand. The new constraints based on geomorphological mapping and sixty-six cosmogenic 10Be surface exposure ages offer the opportunity to test hypotheses about the climate system, to better understand the processes that drove ice retreat and readvance during the Last Glacial Maximum and the subsequent glacial termination.

Reconstructions of past glacier geometries indicate that the local ELA was depressed by ~880 m and climate was 5±1 °C colder than present (1981–2010) at 19.8±0.3 ka, while ELA was depressed by ~770 m and climate was 4.4±0.9 °C colder at 16.7±0.3 ka. Subsequent estimations suggest ELA elevations at 14.5±0.3 ka, 13.6±0.3 ka, and 12.6±0.2 ka were ≤700 m, ≤630 m, and ~360 m lower than today. This equates to air temperatures of ≤3.9 °C, ≤3.5 °C, and 2.3±0.7 °C colder than today, assuming no changes in past precipitation.

The small amount of warming estimated in this study between 19.8±0.3 and 16.7±0.3 ka differs somewhat from glacial reconstructions in other major valleys in the Southern Alps, specifically from Rakaia River valley. Robust constraints of glacier changes in the Ahuriri valley between 14.5±0.3 and 12.6±0.2 ka confirm that an early glacier readvance occurred in New Zealand at this time, which has been previously recognised with only limited evidence. The reconstructed ELA suggests that the coldest part of the Late Glacial reversal occurred at 14.5±0.3 ka. 

How to cite: Tielidze, L., Eaves, S., Norton, K., Mackintosh, A., and Hidy, A.: Late Quaternary glacier-climate reconstruction in the Ahuriri River valley, Southern Alps of New Zealand, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13860, https://doi.org/10.5194/egusphere-egu24-13860, 2024.

During the Last Glacial Maximum the Valsugana sector in the south-eastern European Alps was characterized by an extensive glacier network that included the large valley glacier belonging to the Adige glacier, through the transfluence in the Fersina area, and major tributaries from the Calamento and Cavè valleys. The glacier surface reached up to 1400 m a.s.l. in the western sector of the study area with a downstream gentle slope to the east. At Borgo Valsugana, the trunk glacier merged with several tributaries and flowed also towards the Tesino plateau to the east, where it merged with the tributary valley glacier. In the Tesino area, the glaciers flowed mainly to the south towards the major trunk glacier. This flowed downstream until Primolano, where the narrow reach of Canal del Brenta dammed its flow. The gorge promoted the bulging of the glacier front and its split into two lobes: the first to the south formed the lateral moraines of Enego and Col del Gallo ending with a seracs cascade; the second lobe to the east merged with the Cismon-Piave glacier. This latter was a major ice-field originated in the central Dolomites and reached its western frontal position above the Corlo gorge (Rossato et al., 2018).

 In this articulate network several nunataks remained ice-free; here, lateral moraines with erratic boulders mark the elevation of the trimline. At Mt. Lefre, three boulders were dated to the LGM with exposure dating method (¹⁰Be). These are the first exposure ages for an LGM glacier in the south-eastern Alps and can be compared to radiocarbon chronologies from other glaciated valleys

In the study area also independent glaciers (Mt. Agaro, Mt. Coppolo, Mt. Cavallara) developed. In the Prealps the large Altopiano dei Sette Comuni plateau glacier had a calculated Equilibrium Line Altitude (ELA) of 1680 m a.s.l. (Rettig et al., 2023), while the Monte Grappa ice cap had a calculated ELA of 1450 m a.s.l. (Baratto et al., 2003; Rettig et al., 2023). The ELA estimates allow insights into the climatic conditions under which the LGM glaciers in the Valsugana evolved.

References

Baratto A., Ferrarese F., Meneghel M., Sauro U. 2003. La ricostruzione della glaciazione Wurmiana nel Gruppo del Monte Grappa (Prealpi Venete). In: Biancotti, A., Motta, M. (Eds.), Risposta dei processi geomorfologici alle variazioni ambientali. Brigati G., Genova, pp. 67–77.

Rettig L., Monegato G., Spagnolo M., Hajdas I., Mozzi P. 2023. The Equilibrium Line Altitude of isolated glaciers during the Last Glacial Maximum – New insights from the geomorphological record of the Monte Cavallo Group (south-eastern European Alps). CATENA, 107187.

Rossato S., Carraro A., Monegato G., Mozzi P., Tateo F. 2018. Glacial dynamics in pre-Alpine narrow valleys during the Last Glacial Maximum inferred by lowland fluvial records (northeast Italy). Earth Surface Dynamics, 6, 809-828.

How to cite: Monegato, G., Rettig, L., Rossato, S., Kamleitner, S., Ivy-Ochs, S., Modesti, A., Gosio, F., Demozzi, M., Rinaldo, M., Marcato, E., Trentini, T., Martin, S., and Mozzi, P.: The valley glacier network of the Valsugana (south-eastern Alps) during the LGM: Chronology and Equilibrium Line Altitudes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15483, https://doi.org/10.5194/egusphere-egu24-15483, 2024.

Palaeo-ice sheets leave behind a landform record that we can decipher to understand glaciological processes and the responses of ice sheets to warming climates. Reconstructions of past ice sheet behaviour can inform numerical ice sheet models and are important for understanding ongoing glacio-isostatic uplift. The Scandinavian Ice Sheet, which was the largest component of the Eurasian Ice Sheet Complex during the last glaciation, glaciated Fennoscandia and northern Europe. Since the 19^th Century, there has been considerable research into the deglaciation pattern of Scandinavian Ice Sheet during the last Glacial-Interglacial Transition. However, many reconstructions of retreat have been conducted at local-regional scales, which can be difficult to reconcile across ice sheet-scales, and ice-sheet scale reconstructions based on consistent approaches to mapping and data sources are rare. These inconsistencies lead to difficulties in creating ice-sheet wide reconstructions of deglaciation.

Using the glacial inversion approach, we combine our independently mapped ice marginal landforms, subglacial meltwater routes, and subglacial bedforms to produce a consistent ice sheet-scale assessment of deglaciation patterns across Norway, Sweden, and Finland. Here we present our latest version of the deglaciation pattern for the last Scandinavian Ice Sheet. This reconstruction has many similarities to previous efforts but adds significant detail. For example, in addition to overall retreat patterns, we capture instances of ice margin readvance. We also reconstruct a complex retreat pattern with the ice sheet breaking into small ice masses located within and adjacent to the Scandinavian Mountains.

How to cite: Boyes, B., Dulfer, H., Dewald, N., Butcher, F., Clark, C., Ely, J., and Hughes, A.: Deglaciation pattern of the last Scandinavian Ice Sheet across Fennoscandia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16440, https://doi.org/10.5194/egusphere-egu24-16440, 2024.

Overdeepenings are glacially shaped basins, incised into the bedrock deeper than the fluvial base level by subglacial erosion. Their sedimentary fillings are important archives for understanding glacial and postglacial history and the glacial impact on environmental transformation. Investigation of overdeepened features and their sedimentary contents is essential for understanding the processes and drivers of subglacial erosion, the timing and sequence of past glaciations, and accordingly their cumulated impact on landscape and topography.

This study is centred around an already acquired high quality drill core plus a correlating outcrop on the highest summit of Upper Swabia (The Hoechsten) in the North of the Lake Constance area (southwestern Germany). We investigate an overdeepening in an exceptional stratigraphic position: The sediment succession at Hoechsten is one of only a few examples of glacial basin fills that are correlated with the Early Pleistocene, and a key profile for this otherwise merely poorly constrained period. Situated in an elevated position, it is considered a component of an old highland-ramp topography that has since been largely reshaped over the course of repeated glaciations (Ellwanger et al. 2011).

Besides sedimentological analysis we apply standard geotechnical methods to reconstruct the deglaciation and potential phases of readvancement. Geotechnical data has proven valuable for the identification of a glacial sediment component, of previous mechanical loading by ice, or of the modification of a deposit by non-glacial processes. Furthermore, we compare micromorphological structures on the basis of microscale computed tomography analysis with results of a previously conducted thin-section study (Menzies & Ellwanger 2011). In the future, these analyses will be complemented by a multi-method dating approach (integrating e.g. luminescence and paleomagnetic properties and cosmogenic nuclides).

References:
Ellwanger, D., Wielandt-Schuster, U., Franz, M., & Simon, T. (2011). The Quaternary of the southwest German Alpine Foreland (Bodensee-Oberschwaben, Baden-Wuerttemberg, southwest Germany). E&G Quaternary Science Journal, 60(2/3), 306-328, DOI 10.3285/eg.60.2-3.07
Menzies, J. & Ellwanger, D. (2011). Insights into subglacial processes inferred from the micromorphological analyses of complex diamicton stratigraphy near Illmensee-Lichtenegg, Hoechsten, Germany. Boreas, 40(2), 271-288, DOI 10.1111/j.1502-3885.2010.00194.x

How to cite: Pomper, J., Bamford, C., Preusser, F., Wielandt-Schuster, U., and Gegg, L.: Early stage Quaternary overdeepening in Upper Swabia - Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16566, https://doi.org/10.5194/egusphere-egu24-16566, 2024.

During the Marine Isotope Stages (MIS) 2-3, the Patagonian ice sheet (PIS) stretched along the southern Andes from 55°S to 38°S. Based on Glacial geomorphological and geochronological evidence, its western margin reached the Pacific Ocean, while its easternmost sectors were characterised by terrestrial lobes that fed large paleo-glacial lakes. Previous studies suggest that the maximum extension of PIS was reached towards the end of the MIS 3. However, uncertainty remains regarding the glacial and climate evolution that led to its maximum extension in asynchrony with the Northern Hemisphere ice masses and Antarctica.

We present an ensemble of transient numerical simulations of the PIS that were carried out through the MIS 3 and MIS 2, aiming to determine the range of climate conditions that match the field-derived ice sheet geometries and climate history of the Patagonian ice sheet prior the global LGM, which corresponds to the timing of the local glacial maximum and its subsequent deglaciation. Furthermore, we bracketed the spread in possible ice volumes and sea level contributions originating from uncertainties in the internal parameters and external forcings. The model ensemble is built using the ice sheet model SICOPOLIS forced by phases 3 and 4 of the Paleoclimate Modeling Intercomparison Project (PMIP). The transient simulations are based on a glacial index method by using a combination of Patagonian offshore records and Antarctic cores. Our results indicate that the regional climate conditions required to reproduce a realistic growth and demise of the PIS through the Late Quaternary are not captured by coarse-resolution global climate models, implying the need of climate models with high spatial resolution and a well-constrained ice mask, which could reproduce the necessary cooling to promote the adequate growth. Our results also suggest that the MIS3 should have witnessed colder conditions than those modeled at the LGM by global climate models to realistically simulate the evolution of the PIS in agreement with geological archives.

How to cite: Castillo-Llarena, A., Retamal-Ramirez, F., Bernales, J., Jacques-Coper, M., Prange, M., and Rogozhina, I.: Unravelling the Patagonian Local Last Glacial Maximum and its Deglaciation History from a Modelling Perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17599, https://doi.org/10.5194/egusphere-egu24-17599, 2024.

Pleistocene Glaciations and their effects on Alpine topography have drawn scientific attention since well before the days of Penck and Brückner (1909), although this indomitable pair left a strong legacy to build upon. The onset of large-scale glaciations in the Alps relative to the growth of the other great Northern Hemisphere ice sheets remains a first-order question in the Quaternary sciences. Previous chronologies from the southern Alpine Foreland based on magnetostratigraphy (Muttoni et al. 2003) and from the northern Alpine Foreland based on ¹⁰Be-²⁶Al burial dating (Knudsen et al. 2020) converge around 1.0–0.9 Ma, during the Middle Pleistocene Transition (~1.2–0.8 Ma).

Extensive moraine complexes in the southern Alpine Foreland, such as those at Ivrea, offer a valuable opportunity to determine when glaciers advanced beyond the Alpine rangefront for the first time. The Ivrea Morainic Amphitheatre comprises interbedded glacial tills at the outlet of the Aosta Valley in NW Italy (Gianotti et al. 2015). The oldest tills have been attributed by previous workers to a stage before the Matuyama-Brunhes magnetic polarity reversal (~ 0.8 Ma).

We apply ¹⁰Be-²⁶Al burial dating to the oldest glacigenic deposits at Ivrea, utilizing the Monte Carlo-based inversion model, P-PINI (Particle-Pathway Inversion of Nuclide Inventories). Our preliminary results indicate that the first major glacial advance occurred ~ 1.3–1.1 Ma. We combine these analyses with detrital thermochronology measurements on pebbles collected from preglacial sediments at Ivrea. These pebbles indicate provenance from the Austroalpine Massifs and an absence of the External Massifs (Mont Blanc granites)-in contrast to the present-day Aosta Valley sediments, which show the cooling signature of the Mont Blanc granites. 

We reflect on the coincident timing of the exhumation of the External Massifs and the earliest large-scale Alpine glaciations at the onset of the Middle Pleistocene Transition.

How to cite: Guha, S., Valla, P., Yla-Mella, L., Knudsen, M. F., Gianotti, F., Monegato, G., Serra, E., Stübner, K., Lachner, J., Rugel, G., and Jansen, J. D.: The first glaciers at Ivrea, southern Alpine Foreland , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19781, https://doi.org/10.5194/egusphere-egu24-19781, 2024.

Cirque valleys are typical landforms of formerly glaciated high mountains, which also play an important role in paleoclimate reconstruction. In Bulgaria, the Rila (highest peak, Musala 2925 m) and Pirin (highest peak, Vihren 2915 m) mountains were the only terrains, where significant glacial cover developed during the Pleistocene glaciations, although some minor glacial landforms also exist elsewhere in Bulgaria. During the glacial periods, valleys of the Rila and Pirin Mts were re-shaped by glacial erosion and currently are characterized by glacial cirques and U-shaped valleys reaching lengths of 22 km (in Rila) and 13.5 km (in Pirin).

In these two mountain ranges, a comprehensive, quantitative geomorphometric analysis of glacial cirques valleys has not yet been carried out, thus we try to fill this gap with the present work. Primarily, digital terrain models and GIS tools were used to delineate the cirques. Based on the delineations, the main morphometric parameters of the cirques (elevation, relative depth, width, length, area, aspect, slope conditions, etc.) were calculated and a careful statistical analysis of these parameters was performed. Both the topographic orientation and the lithological structure of the two neighbouring mountains are different, that gives us an opportunity for a comparison of topo-climatic and lithological factors of cirque development. For instance, based on elevation, size and orientation of the cirques, the possible correlations with the paleoclimate factors, like exposure or moisture transport directions can be examined. Finally, our results were compared with available cirque valley morphometric data of other high mountains rising on the Balkan Peninsula.

How to cite: Telbisz, T., Krasznai, M., Gachev, E., Gikov, A., and Ruszkiczay-Rüdiger, Z.: Glacial cirque morphometry of Rila and Pirin Mountains (Bulgaria), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20311, https://doi.org/10.5194/egusphere-egu24-20311, 2024.

• Reconstructing the extent and timing of palaeoglaciers and their associated climate is of great importance for understanding the responses of glaciers to climate change. Glacial landforms are well-preserved in Zheduo Shan, one of the high mountain ranges on the eastern Tibetan Plateau (TP). However, few studies have constrained glacial chronologies and estimated palaeoclimate in this area. We investigated the glacial advance during the Last Glacial Maximum (LGM) in Zheduo Shan using 10Be surface exposure dating. We then reconstructed the extent and thickness of LGM glaciers based on geomorphological mapping and a flowline-based glacial modelPalaeoIce. Eleven 10Be exposure ages confirmed a major LGM glacial advance between 20.0 ± 3.2 ka and 19.3 ± 2.8 ka. The reconstructed LGM glaciers in this mountain range covered an area of 499.16 km2 with an average ice thickness of 54.4 m and a total ice volume of 52.82 km3. The regional average equilibrium-line altitude (ELA) was estimated as 4524 ± 140 m, 535 ± 140 m lower than the present value. Based on the empirical relationship between precipitation and temperature (P-T model) at the ELAs on the TP, the temperature and precipitation were estimated as 3.10–5.27 ◦C and 10–16% lower during the LGM than the present values, respectively. These results suggest that the LGM glacial advance was more sensitive to temperature than precipitation in Zheduo Shan.

How to cite: Yang, Y.: Reconstruction of palaeoglaciers and palaeoclimate in Zheduo Shan, Eastern Tibetan Plateau, during the Last Glacial Maximum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21174, https://doi.org/10.5194/egusphere-egu24-21174, 2024.