In the past the West Antarctic Ice Sheet (WAIS) extended beyond its present-day limits, sometimes as far as the continental shelf edge during cold periods, such as the Last Glacial Maximum (LGM, ~19-23 ka). Sediment deposited at the base of grounded ice is known as subglacial diamicton (or ‘till’). In addition, diamictons can be formed in a range of other glacimarine depositional environments including sub-ice shelf or seasonally open marine settings, as iceberg rafted and scoured diamictons, or glacigenic debris flows. Whilst there has been some progress in characterising subglacial and iceberg-keel scoured diamictons at both macro- and micro-scales, historically it has been difficult to distinguish between different types of diamictons formed in very different settings. This is particularly true for areas where several glacial and glacimarine processes operate, and thus, overprint each other. However, distinguishing between the different types of diamictons is crucial if we are to reliably reconstruct the maximum extent of the WAIS in the past and the timing of its retreat. This information is urgently needed for ice sheet and climate models that are used to predict future WAIS changes and resulting global sea-level rise. The aim of this study is to macro- and microscopically examine, and determine the origin of, diamictons from the outer shelves of the Bellingshausen Sea (core GC371) and the Amundsen Sea (cores VC430, VC436), in West Antarctica. Although the three cores examined in this study were retrieved from sea floor areas affected by iceberg-keel scouring, their diamictons may also represent any or all of the other aforementioned diamicton-forming processes. Micromorphological analyses show that diamictons in all three cores have undergone stress resulting in pervasive deformation subsequent to deposition. Cores GC371 and VC430 contain diamictons with more abundant and better developed microstructures than core VC436, which suggests cores GC371 and VC430 have undergone more intense deformation than core VC436. Micromorphological structures and features at all three core sites demonstrate complicated and/or inverse down-core deformation patterns, which often do not complement a traditional strain profile, and are not consistent between core sites. This indicates potential overprinting of structures at several horizons after multiple deformation events. Future research should focus on attempting to identify and unravel separate deformation events in diamictons, and to further distinguish between diamictons formed in different Antarctic depositional settings.
How to cite: Linch, L.: The micromorphology of iceberg-keel scoured diamictons from the Bellingshausen and Amundsen Seas: An approach to improving reconstructions of West Antarctic Ice Sheet extent., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9400, https://doi.org/10.5194/egusphere-egu25-9400, 2025.
The Ediacaran Period (635 Ma to 538.8 Ma) was a crucial transition interval for the Earth System between the Proterozoic and Phanerozoic worlds. Ediacaran rocks preserve evidence for both profound changes to the global carbon cycle via the stable carbon isotope record, and the emergence of ecosystems containing complex macroscopic organisms, including early animals, through the trace and body fossil records. Nevertheless, geological evidence of Earth’s climate through the Ediacaran is poorly constrained and often equivocal, which limits deeper comprehension of how the Earth System functioned during this time, and the possible feedbacks between biotic and climatic evolution.
The Ediacaran Period is sandwiched between the Cryogenian Period (720 Ma to 635 Ma), which may have been characterised at times by extreme ‘Snowball Earth’ icehouse conditions, and the Cambrian Period (538.8 Ma to 486.85 Ma), which was likely a prolonged greenhouse interval. There is abundant geological evidence of glaciation in the mid- to late Ediacaran (~593 to 579 Ma) that, whilst challenging to correlate in detail, appears to break the ‘Snowball Earth’ mould of globally distributed low altitude ice seen during the preceding Cryogenian Period. In particular, a cluster of glacial deposits on palaeocontinental Avalonia and Gondwana are associated with this interval, with glaciation considered to have terminated just prior to the first appearance of early animal fossils.
Here, we critically evaluate the depositional ages and likely glaciogenicity of candidate glacial deposits of plausibly mid-Ediacaran age. Our re-evaluated dataset provides a framework for assessing the geographical and temporal extent of icehouse conditions in the mid-Ediacaran. We combine this framework with new climate and icesheet model simulations to examine the possible nature of the climate system through this interval. Our data-model comparison supports the hypothesis that, in contrast to the preceding Cryogenian-style ‘Snowball Earth’, the mid-Ediacaran icehouse followed the Phanerozoic paradigm of low altitude ice confined to the mid- to high palaeolatitudes, a pattern of glaciation that continues to the present day.
How to cite: Wong Hearing, T. W., Pohl, A., Tindal, B. H., Vandyk, T. M., Fluteau, F., Liu, A. G., Harvey, T. H. P., and Williams, M.: Earth’s first Phanerozoic-style icehouse in the late Neoproterozoic, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12696, https://doi.org/10.5194/egusphere-egu25-12696, 2025.
The Laurentide Ice Sheet (LIS) covered vast areas of North America during the Wisconsinan period. The melting of the LIS resulted in the release of a substantial volume of freshwater into the Labrador Sea, thereby affecting the strength of the Atlantic Meridional Overturning Circulation (AMOC), a critical component of the global climate system. Consequently, the investigation of the dynamics of the LIS provides a framework for predicting the melting of analogous ice sheets, such as the Greenland Ice Sheet, in the future. This study presents an updated Quaternary stratigraphy of the Labrador Shelf, based on 2D multi-channel seismic reflection data from three glacial cross-shelf troughs: Okak, Hopedale and Cartwright. Seven different seismic units are described and interpreted in terms of their origin and deposition processes. We observe de- and interglacial deposits between glacial till layers for the first time on the Labrador Shelf. Additionally, sets of incised channels at three different depth intervals have been discovered. The data gathered indicates that these channels are of subglacial origin. Finally, the observations are combined into a shelf evolution model consisting of eight stages and spanning two glacial-interglacial cycles. Our study demonstrates that the cross-shelf troughs of the Labrador Shelf were not fully excavated by the LIS during the Wisconsinan glaciation. Instead, deeper sediment layers contain evidence of older glacial-interglacial cycles. Consequently, the sedimentary succession can be used as an archive to reconstruct the dynamics of glaciations during Quaternary glacial-interglacial cycles.
How to cite: Lenz, K.-F., Gross, F., Gebhardt, C., Lohrberg, A., Schneider, R., Kolling, H., Riefstahl, F., Bautista, O. M., Thamm, V., and Krastel, S.: Reconstructions of the Laurentide Ice Sheet based on Quaternary sediment architecture and buried glacial channels on the Labrador Shelf, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4144, https://doi.org/10.5194/egusphere-egu25-4144, 2025.
The subglacial environment is a key part of glacier dynamics, and the ‘slipperiness’ of the bed has shown to be related to the rate of sea level rise. Investigations of the subglacial hydrological system associated with soft beds are rare. Studies from modern glaciers have revealed there is a continuum in subglacial fluvial behaviour associated with a deforming bed, from channelised to distributed. We use data from wireless in situ subglacial probes, GPR, glacier velocity data from remote sensing and GNSS and drone surveys to investigate this continuum. We then use this data to relate this to the geomorphology and sedimentology from both modern and Quaternary melt-water corridors, in order to reconstruct past subglacial processes.
How to cite: Hart, J., Martinez, K., Baurley, N., Robson, B., and Andrews, A.: Subglacial meltwater corridors and their relationship to the soft-bed subglacial hydrological continuum, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15497, https://doi.org/10.5194/egusphere-egu25-15497, 2025.
Despite a significant body of work utilizing terrestrial cosmogenic nuclide dating to examine the late Quaternary glacial history of the mid to northern Rocky Mountains, we lack an understanding of alpine glacial and ice cap responses to climate change in the southern Rocky Mountains (SRM) and the Southwestern United States (SWUS). While limited work has examined the timing of glacial advance and retreat in the SRM of New Mexico using relative age dating techniques, only one study to date has examined last glacial maximum glacier extents in a mountain valley in the southern Sangre de Cristo mountains (SdCm). The lack of age control for the southernmost Rocky Mountain glacial sequences limits our understanding of the timing for SWUS glacial retreat in response to late Quaternary warming periods. Additionally, while limited work has suggested an absence of Holocene glaciation in valley glacier systems at the far southern extreme of the SdCm near Santa Fe, New Mexico, the southernmost limit to Holocene glaciation within the United States remains uncertain.
Here, we develop preliminary moraine chronology, model glacier and ice cap extents, and produce a paleoclimate record throughout the late Quaternary at Costilla Massif in the SdCm of New Mexico. We aim to use the glacial and paleoclimatic records to examine variations in climate between Costilla Massif and other glaciated regions of the Rocky Mountains and test the hypothesis that latest Pleistocene and Holocene glaciation occurred in the SRM. We use 10Be terrestrial cosmogenic nuclide exposure dating of quartz monzonite boulders to develop a glacial chronology for six moraines in two glaciated valleys at Costilla Massif. We use the updated glacial energy/mass balance of Plummer and Phillips to (1) model the extent of valley glaciation and (2) determine paleoclimatic deviations from modern conditions required to sustain glaciers at each moraine position. We compare ice cap extents at Costilla Massif with similar small ice caps throughout the southern Sdm to determine changes in extent related to fluctuations in local and regional climate. We then compare our moraine-derived paleoclimate record with similar records elsewhere in the Rocky Mountains and other climatic proxy records throughout the SWUS and SRM regions to provide analysis of warming trends during the Late Quaternary.
Preliminary soil relative age dating techniques indicate glacial landforms at Costilla Massif range in age from MIS6 (~195 – 123 ka) to the Holocene. Given their limited extent and relative lack of soil development, we hypothesize that the youngest cirque glaciers at Costilla Massif are of Holocene age. Additionally, we predict the Costilla Ice Cap persisted into the Holocene. We predict that valley glaciers at Costilla massif began to retreat earlier than occurred in the mid- to northern Rocky Mountains at similar rates to elsewhere in the SdCm. However, the presence of a locally extensive ice cap and local variations in topography and precipitation and temperature regime compared to elsewhere in the SdCm permitted stabilization of cirque glaciation during the early Holocene in contrast to previous studies suggesting a deglaciation of the SdCm by about 15 ka.
How to cite: Feldman, A., Sion, B., Anderson, L., Brugger, K., and Bustard, J.: Quaternary climate inferences for the southernmost Rocky Mountains from cosmogenic dating and glacier modeling at Costilla Massif, New Mexico., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13921, https://doi.org/10.5194/egusphere-egu25-13921, 2025.
Yukon has been repeatedly affected by the northern Cordilleran Ice Sheet (NCIS). Although termed an ice sheet, it is better described as an ice complex, with quasi-independent lobes originating from mountainous areas around the border of Yukon. This ice complex produced irregular, digitate horseshoe-shaped glacial limits largely on the plateau area of central Yukon, at the eastern edge of unglaciated Beringia. These limits have broadly followed a pattern of progressively diminished extent. It is likely that variations in precipitation across the source areas of these lobes affected their extent and timing during various glacial cycles. The growth model of the NCIS is contingent on ice from numerous cirques and ice fields in the source areas eventually amalgamating into these large, coalescent ice lobes. What is unclear is the contribution of cirque and valley glaciers from the few mountainous areas near the limits of glaciation. This research describes the contribution of cirques and valley glaciers in two areas at the glacial limits from MIS 6-2.
Central Ruby Range is in southwest Yukon and was affected by the Saint Elias lobe. It encompasses the limits of MIS 2, 4 and 6 glaciations. Stratigraphic analysis paired with 10Be surface exposure dating indicates extensive local ice production from cirques and plateau surfaces during MIS 2. During early MIS 2, local valley glaciers advance to the edge of the range but had retreated before inundation by the St. Elias lobe, likely due to local precipitation reduction. These alpine ice centres were responsive to deglacial climatic fluctuations and hosted significant re-advances during the Older Dryas, despite their location in the rain shadow of the St. Elias Mountains and during rapid retreat of the St. Elias Lobe. The MIS 4 limit is slightly more extensive than the MIS 6 limit here, likely because local ice contributed to this portion of the St. Elias Lobe. The record and limit of the MIS 6 glaciation is poorly constrained here but 150 km to the NW, MIS 6 is 4 km more extensive than 4.
Granite Creek is in the Gustavus Range in central Yukon at the MIS 2 limit of the Selwyn lobe. During MIS 2 a tongue of the Selwyn lobe occupied the lower portion of Granite Creek, forming a lake. Cirque glaciers near the margin were overrun by the Selwyn lobe. Cirque glaciers terminating in the lake advanced due to floating ice margins, but these maximum limits are not reflected in the geomorphic record; their well-defined moraines are recessional from this maximum. Stratigraphic studies indicate extensive MIS 4 cirque glaciation but no evidence of a proximal Selwyn lobe. During MIS 6, cirque glaciers were extensive early enough that the Selwyn lobe did not inundate local cirque valleys even though the entire area was overrun.
This research indicates peripheral ice accumulation could contribute to the NCIS. However, variations in precipitation imply that peripheral ice sources were largely out of sync with local ice sources.
How to cite: Ward, B., Cronmiller, D., Steinke, J., and Bond, J.: Distal Cirque Contribution to the Northern Cordilleran Ice Sheet, Yukon, Canada, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13259, https://doi.org/10.5194/egusphere-egu25-13259, 2025.
Glacial erosion shapes alpine landscapes, produces chemically reactive mineral surfaces integral to the carbon cycle, and informs glacier dynamics applied in ice sheet models. Quantifying primary bedrock erosion has remained elusive due to the inaccessibility of the ice-bed interface. Many erosion estimates thereby rely on basin-wide sediment accumulation rates that can include reworked sediment, potentially causing overestimates of glacial erosion. Here, we quantify glacial erosion of primary bedrock using 60 paired cosmogenic in situ 14C-10Be measurements from new and published bedrock samples spread across 10 glacier forefields from 60° N to 16° S. We apply a Monte Carlo forward model that tests millions of scenarios of glacier exposure, burial, and erosion to identify scenarios capable of replicating the measured nuclide concentrations. Our new data are from a glacier in southeast Alaska where samples were collected at two scales: landform-scale along a single roche moutonnée to investigate abrasion versus plucking and valley-scale from the modern glacier terminus to its pre-industrial moraine to constrain glacier length fluctuations. The other 9 sites are across-valley transects abutting the terminus of the modern glacier. We compare our results to modeled erosion rates from a power-based abrasion law and Elmer/Ice glacier model simulations. The cosmogenic nuclide-based erosion rates are consistent across scales and sites, overlapping with the modeled erosion rates that are concentrated below 0.3 mm yr-1. These findings suggest glacial erosion rates of primary bedrock are much lower than predicted from modern sediment supply studies that reach up to 10 mm yr-1. Our millennial-scale glacial erosion estimates of crystalline bedrock support a modern bias in erosion estimates (e.g. Ganti et al., 2016) with implications for landscape evolution and sediment delivery models.
How to cite: Jones, A., Brooks, J., Marcott, S., Zoet, L., Lifton, N., Gorin, A., Shakun, J., Helanow, C., and Caffee, M.: Glacial erosion rates of primary bedrock from in situ 14C-10Be measurements are low, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-321, https://doi.org/10.5194/egusphere-egu25-321, 2025.
To date, the Icelandic Ice Sheet (IIS) and Patagonian Ice Sheet (PIS) have been poorly understood with regard to their configuration, dynamics, and evolution during the last glacial cycle. The few glaciological modelling studies of the IIS and PIS to date have placed minimal attention on addressing model uncertainties. As such, their inferential value is poorly interpretable.
To address this, we present the results of history matchings of the 3D Glacial Systems Model (GSM) against curated sets of paleo constraints for the last glacial cycle IIS and PIS. History matching identifies a set of model simulations that are not ruled out given available data constraints and robust uncertainty analysis (including both model and data uncertainties). As such, it aims to “bracket reality” as opposed to the much more difficult task of determining a meaningful most likely chronology.
The GSM is a thermo-mechanically coupled glaciological model with hybrid shallow ice and shallow shelf/stream physics. The climate forcing consists of a fully coupled energy balance climate model and glacial indexed climate forcing using the results of PMIP3 (Paleo Model Intercomparison Project). Approximate 30 GSM ensemble parameters partially account for uncertainties in climate, basal drag, and marine ice processes. The GSM configuration includes fully coupled visco-elastic glacio-isostatic adjustment enabling physically self-consistent relative sealevel predictions. Our presentation focuses on bracketing chronologies for the last glacial cycle IIS and PIS as well as disentangling the relative contribution of atmospheric and marine forcings on mass loss during the deglaciation.
How to cite: Goffin, A., Tarasov, L., Benediktsson, Í. Ö., Licciardi, J., Rivera, A., and Lambert, F.: History Matching of the Last Glacial Cycle Model for the Icelandic and Patagonian Ice Sheets, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-501, https://doi.org/10.5194/egusphere-egu25-501, 2025.
During the Last Glacial Maximum (26,000-19,000 years B.P.; Clark et al. 2009), the Patagonian Ice Sheet (PIS) formed a contiguous ice cap over the southern Andes from 38° to 55° S, with a sea level equivalent to 1.5 m (Davies et al., 2020). Despite recent progress in reconstructing the PIS configuration during the last glacial cycle (Davies et al., 2020), constraints on the timing of PIS retreat and thinning during the last deglaciation remain limited. In order to understand how the PIS responds to centennial and millennial scale changes in climate, we provide geologic constraints to reconstruct the timing of its past area and volume changes and apply numerical ice sheet models to test the sensitivity of the PIS to past climate change. To do this, we apply cosmogenic nuclide dating of exposed bedrock surfaces across the Southern Volcanic Zone in northern Patagonia to document the rates of ice sheet thinning during the last deglaciation. Our data are from elevations of 200-2000 m and span a ~400 km latitudinal transect. Transient model simulations of the PIS with the Ice Sheet and Sea-level System Model (ISMM) were performed to test the sensitivity of the northern PIS to changing climatological inputs driven by the Trace-21ka experiment (He, 2011). Our cosmogenic nuclide ages document the onset of rapid ice sheet thinning that initiated at ~18,000 years B.P. with accelerated and widespread deglaciation occurring after 15,000 years, which is in good agreement with our model simulations (Cuzzone et al. 2024). Together, our data and model simulations show that ice sheet thinning and retreat occurred earlier in the northern sector of the PIS than in the south (Cuzzone et al., 2024), which we attribute to a reduction in wintertime precipitation driven by a poleward migration of the westerly winds. Our work highlights the important, but often overlooked, role of precipitation in modulating both the timing of and magnitude of surface mass balance changes of mid-latitude ice sheets at the millennial-scale following the last glacial period.
How to cite: Romero, M., Marcott, S., Cuzzone, J., Tremblay, M., and Jones, A.: A Data-Model Comparison of Ice Sheet Demise in Northern Patagonia During the Last Deglaciation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-774, https://doi.org/10.5194/egusphere-egu25-774, 2025.
Reconstructing the last glaciation of the European Alpine Ice Field via numerical modelling has been challenged by persistent model-data disagreements, including large overestimations of its former thickness. Here, we tackle this issue by applying the Instructed Glacier Model, a three-dimensional, high-order, and thermo-mechanically coupled model enhanced with physics-informed machine learning. This new approach allows us to produce an ensemble of 100, Alps-wide and 17 thousand-year-long (35-18 ka) simulations at 300 m spatial resolution. Unfeasible with traditional models due to computational costs, our experiment substantially increases model-data agreement in both ice extent and thickness. The model-data offset in ice thickness, for instance, is here reduced by between 200% and 450% relative to previous studies. The results yield implications for more accurately reconstructing former ice velocities, ice temperatures, basal conditions, glacial erosion processes, glacial isostatic adjustment, and climate evolution in the Alps during the Last Glacial Maximum. Furthermore, the switch to GPU-based computations enables us, for the first time, to also couple our Alpine Ice Field model with three-dimensional and time-transgressive ice advection of particles (tens of millions). Here, particles are seeded to mimic both the subglacial (e.g. abrasion, plucking) and supraglacial (e.g. rockfall) origins of glacially-transported sediments. Using our ensemble best-fit simulation, we present the results of tracking the sink-to-source transport trajectories of distinct LGM ice-contact deposits (e.g. terminal moraines), and the LGM source-to-sink transport trajectories of specific surface lithologies, throughout the Alps. We find that modelling the Alps-wide glacial transport of particles also helps us better understand the complex internal ice dynamics of the former Alpine Ice Field, including transfluences and the zipping/unzipping behaviours of different tributary glaciers. More generally, this work demonstrates that physics-informed AI-driven glacier models can overcome the bottleneck of high-resolution continental-scale modelling required to accurately describe complex topographies and ice dynamics.
How to cite: Leger, T., Jouvet, G., Kamleitner, S., Mey, J., Herman, F., Finley, B., Ivy-Ochs, S., Vieli, A., Henz, A., and Nussbaumer, S.: A data-consistent, high-resolution model of the last glaciation in the Alps achieved with physics-driven AI , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15931, https://doi.org/10.5194/egusphere-egu25-15931, 2025.
Understanding glacier changes during the Holocene provides key insights into climate variability and cryosphere dynamics. Villarrica volcano (39°S), situated within the Southern Volcanic Zone (SVZ) of Chile, preserves a well-defined record of past glacial extents, with moraines marking post-Last Glacial Maximum (LGM) glacial extents. Despite its potential, the glacial history of Villarrica and the SVZ still remains poorly constrained, limiting our understanding of glacier-climate interactions during the last deglaciation and Holocene.
We present new cosmogenic 3He surface exposure ages from 25 olivine-bearing moraine boulders to better constrain the glacial chronology at Villarrica during the late Holocene. Our chronology reveals multiple phases of moraine formation, including Neoglacial advances at 3350 ± 140 years (n=3) and 1740 ± 225 years (n=3), Little Ice Age (LIA; n=7) advances between 720 ± 340 and 370 ± 220 years, and the onset of modern retreat at 100 ± 50 years (n=12). These advances correlate with shifts in the Southern Westerly Winds (SWW), with Neoglacial advances driven by enhanced moisture delivery, while LIA advances reflect reduced ablation during cooler temperatures. Our findings also demonstrate extended ice positions during the industrial era until the early-to-mid 1900s which corresponds with regional evidence of delayed industrial era warming in Patagonia. Furthermore, the historical volcanic activity at volcanoes like Villarrica can significantly influence glacial landscapes and the preservation of moraines. This study provides a unique opportunity to reconstruct glacial behavior in a highly active volcanic region and offers valuable context for understanding the interactions between volcanic activity, climate, and glacial dynamics in the Southern Hemisphere throughout the Holocene.
How to cite: Orellana-Salazar, Y., Marcott, S. A., Tremblay, M. M., Moreno-Yaeger, P., Romero, M., and Mixon, E. E.: A 3He-based Holocene glacial chronology from Villarrica volcano, Chile, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-320, https://doi.org/10.5194/egusphere-egu25-320, 2025.
Tunnel valleys are impressive erosional landforms and may attain extreme depths of almost 600 m. Open and buried tunnel valleys have been mapped in many formerly glaciated sedimentary basins. Characteristics of tunnel valleys include undulating basal profiles, abrupt terminations and steep flanks, all indicative of subglacial incision by pressurised meltwater discharge. Tunnel-valley formation is primarily controlled by climatic and glaciological factors. However, the structural inventory, such as faults and salt structures, have been invoked as controlling the location and orientation of tunnel valleys. To identify correlations that may indicate such a structural control, we compare the distribution and orientations of buried Pleistocene tunnel valleys in the North German Basin to the regional structural inventory.
Our analysis shows that deep tunnel valleys are restricted to areas with thick erodible Cenozoic deposits. The correlation between the trends of tunnel valleys, faults and salt structures varies between the analysed structural regions. The orientations of tunnel valleys commonly follow the trends of faults and salt structures in regions where the structural trend is NNW-SSE to E-W and ice-flow directions were approximately parallel to this trend. However, correlations are rarely observed if the regional structural trend is NW-SE to WNW-ESE and ice advances occurred thus normal or oblique to the regional fault trend. Faults active under the present-day stress field typically are NNW-SSE to NE-SW trending normal faults. Therefore, the strikes of neotectonically active faults were commonly favourable for tunnel-valley incision and may have promoted subglacial erosion. No clear correlation between the orientations of tunnel valleys and elongated salt structures can be identified.
A major motivation for this study was the potential impact of future glaciations and tunnel-valley incision on the long-term safety of radioactive waste repositories. Our results demonstrate that the presence and orientations of faults and salt structures, however, do not provide consistent indicators for future tunnel-valley incision.
How to cite: Lang, J., Bebiolka, A., Noack, V., Schützke, J., Weihmann, S., and Breuer, S.: Does the structural inventory control tunnel-valley formation? – Insights from the North German Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3674, https://doi.org/10.5194/egusphere-egu25-3674, 2025.
The seafloor geomorphology of glaciated continental margins occasionally hosts relict glacial landforms that serve as proxies of the ice sheet dynamics. The Baltic Sea is a relatively shallow, epicontinental, young sea whose formation after the last deglaciation was modulated by global sea-level fluctuations and isostatic adjustments. During the last glaciation, the Baltic Basin (BB) was one of the major advance corridors of the Fennoscandian Ice Sheet (FIS) towards the Central European Plain. It hosted the Baltic Ice Stream Complex – a zone of potentially highly dynamic, warm-based, fast-flowing ice that drained central parts of the ice sheet. Therefore, BB is a key region for reconstructing the dynamics of the last FIS southern sector. However, the availability of high-resolution bathymetric data which may better constrain BB’s geomorphology is still limited. In particular, the southern part of the BB suffers from a lack of high-resolution bathymetry, which leaves glacial landforms, potentially preserved at the seafloor, largely unrecognized.
Here, we present the results of mapping relict glacial landforms in some areas of the southern BB. The landforms were mapped in ArcGIS based on bathymetric models obtained from the Polish Navy Hydrographic Office, the Swedish Maritime Administration, the General Inspectorate of Environmental Protection, and the Rhenish-Westphalian Power Plant as 0.5 to 10 m grids. We identified individual glacial landforms such as subglacial lineations, subglacial ribs, moraine ridges, grounding line landforms, crevasse-squeeze ridges, meltwater channels, eskers and ploughmarks. The mapping was performed by on-screen digitizing at various scales, depending on landform dimensions. The outcome is a GIS map of glacial geomorphological features preserved at the seafloor. This is the first map displaying the distribution and morphology of relict glacial landforms based on high-resolution bathymetric data in the southern BB.
This work was supported by the National Science Centre, Poland (grant no. 2021/41/B/ST10/01086).
How to cite: Tylmann, K., Grinbauma, I., Greenwood, S. L., Piotrowski, J. A., and Kasuła, M.: Relict glacial landforms in the southern Baltic Sea Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5689, https://doi.org/10.5194/egusphere-egu25-5689, 2025.
This study advances our understanding of the glacial history of the Putorana Plateau, Central Siberia, by expanding beyond cirque analyses to encompass a broader suite of geomorphological features. Using high-resolution Arctic DEM (2 m) data, this research systematically maps and assesses key glacial landforms, including moraines, cirques, ice-scoured basins, streamlined bedforms, and other large-scale features indicative of past ice dynamics. The focus spans multiple glacial periods, from the Last Interglacial through the Last Glacial Maximum (LGM), with particular emphasis on the major advances during MIS5b and MIS4.
The mapping builds on the recently completed cirque inventory of the Western Putorana by, incorporating larger features to comprehensively reconstruct the glacial history of the region. Detailed geomorphological analysis aims to delineate ice flow patterns, quantify ice extent, and identify variations in glacial behaviour across different stadials and interstadials. By integrating these findings with existing palaeoclimate data and previous studies on wider Siberian glaciations, this research provides critical insights into the extent and timing of glaciations in the region.
Initial results highlight the Putorana Plateau as a dynamic ice-marginal environment, shaped by successive glacial advances and retreats. The largest glacial extent occurred during the Late Saalian (MIS 6) and was followed by substantial glaciations during MIS 5b (90–80 ka) and MIS 4 (60–50 ka) connected to the Fennoscandian Ice Sheet, to form the wider Eurasian Ice Sheet. These advances, pre-date the more globally recognised LGM at 30–22 ka, revealing a complex history of ice-sheet behaviour influenced by regional climatic and topographic factors.
This study fills a critical gap in the palaeoglacial research of Siberia, where previous investigations have primarily concentrated on the Ural or Kamchatka Mountains and other Weichselian glaciation configurations. By providing the first large-scale geomorphological assessment of the Putorana Plateau, this work not only refines our understanding of Siberian glacial history but also establishes a framework for future studies on palaeoclimate and ice-sheet dynamics in other remote and understudied regions.
How to cite: Oien, R. and Lee, E.: Geomorphological Mapping of the Putorana Plateau: Tracing Glacial Histories from the Last Interglacial to the LGM, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5887, https://doi.org/10.5194/egusphere-egu25-5887, 2025.
The rapid retreat and fragmentation of Alpine glaciers is widely reported as humanity faces dramatic climate change in mountainous regions. This rapid change leads to changes in sedimentary processes, which are exposed in recently deglaciated regions. These Alpine glacier forefields offer a wide spectrum of settings through which the ancient sedimentary record can be interpreted. Glacial valley orientation, slope inclination and lithology, and plumbing of subglacial and englacial meltwater drainage all influence the immediate preservation potential of glacial sediments upon deposition. In this contribution, we explore the geomorphology and sedimentology of the Taschachferner (a valley glacier), presenting a new geological-geomorphological map. This small glacier drains an icefield in the Ötztal Alps, and its current ice margin lies at approximately 2550 m a.s.l. Thus far, the glacial sedimentology and its bedrock geology have not been subject to investigation. The bedrock geology is dominated by E-W striking units of paragneiss and amphibolite, and the latter exhibit a series of well-preserved striations together with meltwater-sculpted bedforms (p-forms). The lower region of the glacier can be divided into two parts: (i) a clean-ice part, on the northern valley side with a low, subdued profile and (ii) a debris covered part at the southern valley side, covered with supraglacial debris. The valley margins are dominated by several generations of lateral moraines, the most prominent of which corresponds to the 1852 Little Ice Age Maximum. A well-developed “hanging sandur” is observed immediately in front of the ice margin. This consists of a series of sand and gravel bars cradled in the lee of an interpreted regional fault cross-cutting the bedrock. Sandur deposition is currently influenced and overprinted by dead ice, influencing the trajectory and location of river channels and gravel bars. This paper provides clear lessons regarding the distribution of ice-margin facies associations, which must be incorporated into models of glacier decay in the context of a rapidly
warming climate.
How to cite: Le Heron, D., Mejias Osorio, P., Heninger, M., and Davies, B.: Sedimentology of a Rapidly Retreating Alpine Glacier: Insights From the Taschachferner, Tirol, Austria, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8572, https://doi.org/10.5194/egusphere-egu25-8572, 2025.
During the Late Palaeozoic Ice Age (LPIA), South Africa was part of the Gondwana supercontinent. It therefore offers remarkably well-preserved outcrops (e.g. Nooitgedacht and Oorlogskloof) that show the extensive glacial influence.
Here, we introduce a newly discovered area in the Northern Cape region where glacially sculpted outcrops reveal a complex relationship between hard bedrock and soft-sediment features. The outcrops feature streamlined structures, clast-rich diamictite, as well as striated surfaces and exceptionally well-preserved flutes, among other features.
The area, which experiences flooding at irregular intervals, serves as an outstanding example of Late Palaeozoic glacial influence and likely represents one of the best-preserved outcrops of pre-Quaternary flutes.
Furthermore, comprehensive mapping of the visible structures enables a detailed analysis of the different phases of glaciation, contributing significantly to our understanding of the complex dynamics of ice flows during the LPIA.
How to cite: Wohlschlägl, R., Mejías Osorio, P., Busfield, M., and Le Heron, D.: In tune with the ice: First description of excellently preserved flutes and other glacial structures from the LPIA in a newly discovered area in South Africa, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9495, https://doi.org/10.5194/egusphere-egu25-9495, 2025.
The European Alps were covered by a large interconnected system of valley glaciers during the Last Glacial Maximum (LGM). Many of the glaciers advanced into the Alpine Foreland leaving large latero-frontal moraine complexes suitable for (direct) exposure age dating and correlation of the ice extent at different times. In contrast to large parts of the Alps, valley glaciers flowing to the east did not reach the Alpine Foreland resulting in limited preservation of datable relicts. Fortunately, two localities at the margin of the Enns and Mur Glaciers have been found, where the requirements (quartz-rich blocks resting on latero-frontal moraine ridges) for age dating using cosmogenic 10Be and 26Al are met.
The Mur Glacier occupied a W-E oriented valley located south of the Niedere Tauern mountain range in Styria. It had several outlets, one of them terminating in the very east at the village Pöls, where a roughly 400 m wide end moraine ridge is preserved. At least two-phases of ice stabilisation are indicated by two to three superimposed ridges. 1.5 m³ Pegmatite-gneiss blocks are embedded in the end moraine ridge, where we collected three samples to determine their exposure age. Age calculation using cosmogenic 10Be and 26Al yields a mean age of 19.6 ± 1.7 ka, whereby the oldest ages were obtained in the outermost part of the ridge following the expected stratigraphic sequence during ice retreat. These ages are in good agreement with other data of end moraines from LGM ice margins around the Alps. More precisely, the age range falls into a second ice re-advance, specified at other locations (especially at the southern alpine rim) but not differentiable at the Mur Glacier.
At the Enns Glacier, which extended north of the Niedere Tauern mountain range, subparallel to the Mur Glacier, a multiphase moraine complex is preserved, however almost all of the boulders are limestone or dolomite. We managed to scout few conglomerate/breccia blocks that contain 1-2 cm quartz components in a fine matrix. Three of them are embedded in the termination area and two additional boulders are located further proximal. Mean exposure ages calculated using 10Be range between 14 and 17 ka. Ages calculated from the same samples using 26Al are even more scattered. This is surprising given the similarities in location, valley orientation, geographical location, and altitude between both sample locations. Results from Enns Glacier definitely do not fall into the LGM period. But field evidence such as the location and morphological height of the ridges, strongly suggest that they were formed during the LGM and not in a Late-Glacial phase. Implementation of a snow/forest cover correction only has a minor impact on the calculated age. It is possible that the large spread in the Enns glacier exposure ages is caused by the lithological heterogenity of the sampled boulders. Large quartz clasts resist weathering for a longer duration while the matrix is continuously removed until one clast falls out and results in a discontinuous accumulation of cosmogenic radionuclides at the surface. Discussion at the conference is appreciated.
How to cite: Griesmeier, G. E. U., Neuhuber, S. M., Braumann, S. M., Reitner, J. M., Le Heron, D. P., Marchhart, O., and Wieser, A.: Cosmogenic radionuclide exposure ages from the Enns and Mur Glaciers in the Eastern Alps (Styria/Austria), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10580, https://doi.org/10.5194/egusphere-egu25-10580, 2025.
The role of large subsurface landforms produced during glaciations of the Pleistocene is still poorly understood with respect to groundwater flow. In particular, so-called tunnel valleys formed beneath ice sheets, acted as drainage systems of glacial meltwater. Their dimensions (up to 5 km width, 400 m depth, 100s of km length) reflect the massive amount of meltwater that incised into and flushed the subsurface beneath ice sheets.
To understand the potential of tunnel valleys as preferential flow pathways of offshore freshened groundwater (OFG) in the southeastern North Sea, we sailed 320 km of marine time-domain controlled-source electromagnetic surveys on 10 profiles using the surface-towed SWAN system on R/V ALKOR. In particular, we aim to answer the following questions: (1) Does the distribution of electrical resistivities indicate the presence of freshened groundwater in the subsurface of the North Sea? and (2) Can we delineate different resistivity distributions inside tunnel valleys?
Here we show our subsurface electrical resistivity distribution from 2D inversions of the TD-CSEM data with and without structural constraints. We compare these results to a dense net of high-resolution 2D seismic reflection data and additional information from core data in similar geological setting, integrating geophysical and geological data.
The subsurface electrical resistivities show good correlation with the structures prevalent in the 2D seismic reflection data, where correlation is strongest for the upper and lower parts of the tunnel valleys. The electrical resistivity distribution also correlates with deeper Paleogene and Neogene sediments showing low electrical resistivities, likely corresponding to brines. These sediments have been updomed into a large anticline due to salt tectonics in the area, which is reflected in the geometry of electrical resistivities. In between the shallow low resistivity Holocene to Pleistocene sediments and the deeper low resistivity Neogene sediments are regions of significantly increased resistivities in Plio-Pleistocene sediments. These regions are interpreted to represent remnant offshore freshened groundwater from the flushing of meltwater below ice sheets during the Pleistocene, likely to be widespread and not limited to the southeastern North Sea.
How to cite: Lohrberg, A., Haroon, A., Moosdorf, N., and Krastel, S.: The role of buried tunnel valleys of the southeastern North Sea for offshore freshened groundwater: New insights from surface-towed time-domain CSEM measurements, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10687, https://doi.org/10.5194/egusphere-egu25-10687, 2025.
Glacial environments are undergoing rapid transformations due to climate change, which can be observed in the sedimentological processes associated with ice masses. In mountain regions, these can vary within a catchment due to controlling factors such as geological setting and debris sources, slope processes and instability, orientation of the glacier, and glacial dynamics. The Rofental is a valley in the Austrian Alps with a rich history in glaciological research, and hosts several glaciers that exemplify some of these differences. However, until now, there has been no detailed sedimentological work done, in spite of the yearly increase in supraglacial debris on many glaciers, as well as significant ice margin and forefield changes. To address this, we present the results of sedimentological and geomorphological mapping from 2023 and 2024, integrating ground-level observations and drone imagery from fieldwork at 3 different glaciers in the Rofental area: the Hintereisferner, Guslarferner, and Vernagtferner. These glaciers have varying degrees of debris cover and, in some cases, exhibit preservation of delicate sedimentary depositional features on the ice itself. Questions arise regarding transport mechanisms of the debris, including the relative influence of englacial meltout, supraglacial stream deposition and mass wasting (e.g. rockfalls and debris flows). The origins of this debris, its impact on preservation of dead ice over the coming years, and its influence on downwasting rates deserve investigation. By studying these glaciers, we can gain insights into how they will continue to evolve over time, compare them to the previous sedimentary record, and potentially revise some of the established characteristics for retreating glaciers.
How to cite: Mejías Osorio, P., Wohlschlägl, R., Davies, B. J., Vandyk, T., Karbacher, S., and Le Heron, D. P.: Glaciers in the Rofental, Ötztal Alps, Austria: a sedimentological perspective, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11750, https://doi.org/10.5194/egusphere-egu25-11750, 2025.
Records of ice-rafted detritus (IRD) from the global oceans indicate the expansion of large Northern Hemisphere ice sheets prior to the Plio–Pleistocene transition. Yet, the geometry of these early ice sheets remains unclear due to limited availability of well-dated terrestrial sediments. In the German and Polish sectors of the North European Plain, chronostratigraphic schemes evolved independently to produce a contrasting picture of regional glacial history. The most divergent points hinge upon the timing and number of alleged Middle Pleistocene Eurasian Ice Sheet (EIS) advances to reach as far south as the Central European Uplands (~51°N).
Here we present 10Be-26Al abundances measured directly in subglacial tills obtained from two locations within ~180 km of the southernmost German-Polish border (Peres, DE; Jaroszów, PL). Using Particle-Pathway Inversion of Nuclide Inventories (P-PINI), we calculate sediment burial ages by matching large arrays of simulated 10Be-26Al pairs to empirical data, accounting for glaciation-induced complexities in pre-burial sample nuclide ratios. These results are supplemented by U-Pb geochronology of detrital zircons within the tills as a means of inferring source area correlations and interpreting former ice flow pathways.
Our findings suggest equivalency between the lower stadial of the Elsterian glacial stage in the eastern North German Plain and the Sanian 1 in the Polish Silesian Lowlands. Despite their conventional respective assignments to MIS 12 and MIS 16, our data indicate an older concordant age (MIS 36–56) for both deposits. This implies a temporal compression of the Polish pre-glacial series and provides evidence of the disputed Narevian glacial stage below the Nidanian. Dating uncertainties allow correlation with either the floristically-defined Pinnau (Menapian) or the older Lieth (Eburonian) cold phases recognized across Germany and northwest Europe. We further examine these correlations in light of our findings from the well-studied Szczerców lignite mine exposures (central PL), ~200 km east, where dating of Sanian 1 and 2 tills in stratigraphic position suggests that they were emplaced between MIS 16 and 22. Collectively, these results point to an Early Pleistocene advance of the EIS, extending to ~51°N at a time when peak glacial global sea levels were ~50–100 m higher than those of the Last Glacial Maximum.
How to cite: Wagner, K., Yla-Mella, L., Margold, M., Knudsen, M. F., Krzyszkowski, D., Wachecka-Kotkowska, L., Wieczorek, D., Rother, H., Wansa, S., Szuman-Kalita, I., Eriksen, B. L., Andersen, J. L., Olsen, J., Sláma, J., and Jansen, J.: An advance of the Eurasian Ice Sheet to the Central European Uplands preceded MIS 16, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14643, https://doi.org/10.5194/egusphere-egu25-14643, 2025.
The Late Palaeozoic Ice Age (LPIA) is Earth’s most recent, severe glacial epoch and in Namibia experienced its acme at about 300-298 Ma. The record of the glaciation in southern Africa is exceptional, and many of the deposits consist of poorly-sorted diamictites of the Dwyka Group that were deposited beneath glaciers or at their margins. The study of these deposits has often been neglected, because sedimentologists have tended to regard these deposits as complex, massive, or confusing. New quantitative approaches to oriented samples developed in the course of Quaternary glacial studies is beginning to change this, and thus this study will consist of a detailed evaluation of oriented diamictite samples recovered from northern Namibia (Opuwo) the Aranos Basin (central-southern Namibia) and the Karasburg Basin (Namibia-South Africa border). The aim of this Masters project is to produce a substantial new set of directional data. Previous authors have proposed diverse and often conflicting ice-flow directions from different data sources, and it is hoped that this controversy can be resolved.
Oriented samples were collected during fieldwork in 2019 and 2023 from five different locations. Each was cut in three directions, ie “north-south”-, “east-west”- and “top”-orientations, and thin sections were prepared from these, which were then scanned in high resolution. These scans are being quantitatively analysed using the “microstructural mapping” method proposed by Phillips et al. (2011). Measuring the direction of the longest axis of the grains in each oriented thin section will be achieved using CorelDraw. The data from CorelDraw is then exported to OpenStereo, a program which is used for structural geology analysis, to draw rose diagrams of clast orientation. The rose diagrams from each sample will thus represent three sides of a cube, and this “pseudo cube” will allow the orientation of clasts to be characterised in 3D space. From this, an understanding of the dynamics of sediment deformation, and thereby ice flow orientation, will be determined. At PANGEO, preliminary results will be presented.
The main goal of my thesis is to contribute to a nuanced paleo-reconstruction through a better understanding of glacial dynamics in the LPIA. This will not only improve understanding of ancient glacial environments in Namibia but also further the understanding of contemporary glacial behaviour through exploitation of well-preserved samples. Given the complex issues in unraveling past ice flow in ancient rocks, many datasets have been combined by previous authors to achieve this (striation orientations on bedrock, crossbed orientations etc). By contrast, this will be the first large and significant database of flow directions from the LPIA sedimentary record of Namibia drawn from one single source.
How to cite: Heninger, M. and Le Heron, D.: Bringing Order to Chaos: Micromorphological Analysis of Late Palaeozoic glacial diamictites , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16663, https://doi.org/10.5194/egusphere-egu25-16663, 2025.
Maladeta Glacier, one of the largest glaciers of the Pyrenees, is located on the Maladeta Massif (Central Pyrenees), close to the highest point of the range, the Aneto peak (42° 37' 52 N, 0° 39' 24 E; 3,404 m a.s.l.). Maladeta Glacier is one of the most meridional ice masses in Europe, and is considered a very good proxy indicator to study the impact of climatic changes on mediterranean mountains.
This glacier is 650 meters long, occupy an area of 24.8 ha and their maximum altitude is ~3,200 meters. At the end of the last century, due to the retreat, the glacier split into two smaller bodies. The main aim of this research is to present an analysis of the evolution of the glacier since the LIA and examine their shrinking. Based on morphological features, the extent of the glacier, their Equilibrium Line Altitude (ELA) and the temperatures in the study were calculated for the following periods: LIA, 1957, 1983, 2006, 2012 and 2018. To estimate the glacier extension during the LIA, the moraines were mapped by using photo interpretation techniques. For the recent phases digital aerial photographs and satellite images were used.
The preliminary results of the research reveal a retreat of the Maladeta Glacier since the LIA. The length of the glacier has been severely reduced, and its area decreased from 128 ha during the LIA to 24.8 ha in 2018. During this period, the ELA has increased from ~2,894 to ~3,108 m a.s.l. These data reveal a huge retreat of the glacier since the LIA, showing an increase of the temperature in the study area of 1.11-1.39°C from LIA to 2018.
How to cite: Campos, N., Alcalá, J., Emmer, A., Sattar, A., Veettel, B. K., and Le Roy, M.: Evolution of the Maladeta Glacier (Central Pyrenees) since the Little Ice Age, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20001, https://doi.org/10.5194/egusphere-egu25-20001, 2025.
The Weichselian Ice sheet extent during the Last Glacial Maximum has not been thoroughly described for the Danish North Sea. Particularly towards the western sector, where studies have tended to focus on the deeper geology. With offshore activities related to the renewable energy transition, focus on quaternary glacial landscape evolution, its geological history and the associated geotechnical challenges has risen.
Regional high resolution seismic mapping combined with conventional and high-resolution vintage seismic data has revealed glaciotectonic thrusting in glacio-lacustrine deposits in the western part of the Danish North Sea. The glacio-lacustrine deposits are part of a laterally extensive unit that covers the entire southern part of the western Danish North Sea revealing evidence of a large ice-dammed lake in front of the Weichselian ice sheet. Deformation of glaciolacustrine sediments has been observed providing geomorphological evidence of the approximate position of the Weichselian ice sheet in the Danish North Sea. Additionally previous ice sheet positions have been identified, revealing a retreat pattern characterized by at least three phases of ice marginal lake development. The drainage of the glacial lake is recorded in the sediments as erosional channels which appears to drain through a prominent landscape feature known as the Elbe Paleo valley. This study presents the geological landscape evolution from the last glacial maximum to the early Holocene with emphasis on the glacial processes that have shaped the area.
How to cite: Prins, L. T., Allaart, L., Christensen, N., Vangkilde-Pedersen, T., Hansen, K., Lauridsen, B., and Knutz, P.: Last Glacial Maximum to early Holocene - ice sheet extent and landscape development in the Western Danish North Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20816, https://doi.org/10.5194/egusphere-egu25-20816, 2025.
