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Understanding the depositional processes on the inner shelf of Antarctica is a significant challenge. This difficulty arises from the heterogeneity of sediment sources, their poor preservation potential due to the advance and retreat cycles of ice bodies, and the impact of relatively strong bottom currents generated by high density contrasts in the water column. These factors contribute to the overall complexity of the glacio-influenced marine environment, particularly below present-day floating ice shelves in correspondence of areas draped in sediments related to Late Pleistocene-Holocene glacial variations. These locations provide crucial information for reconstructing past glacial dynamics driven by global changes. In this study, we present an analysis of glaciomarine deposits collected from the Western Ross Sea, offshore Mario Zucchelli Station, in a protected indentation of the Victoria Land Coast that hosts the Terra Nova Bay polynya. We conducted multi-proxy analyses on three sediment cores sampled from selected seafloor morphological units associated with fluctuations of the grounded ice, which preserve sedimentary facies representative of this distinctive depositional environment. We identified and described six depositional facies, characterized by diagnostic sedimentological, textural and geochemical patterns. Direct observations were integrated with high-resolution geophysical data and geomorphological seafloor analysis. Our findings highlight a Late Pleistocene-Holocene depositional sequence linked to fluctuations in grounded ice, with unconformities and sedimentary patterns potentially related to climatic variations driving ice advances and retreats. [ABSTRACT FROM AUTHOR]

Characterizing the mechanisms influencing the distribution of genetic variation in aquatic species can be difficult due to the dynamic nature of hydrological landscapes. In North America's Central Highlands, a complex history of glacial dynamics, long-term isolation, and secondary contact have shaped genetic variation in aquatic species. Although the effects of glacial history have been demonstrated in many taxa, responses are often lineage- or species-specific and driven by organismal ecology. In this study, we reconstruct the evolutionary history of a freshwater mussel species complex using a suite of mitochondrial and nuclear loci to resolve taxonomic and demographic uncertainties. Our findings do not support Pleurobema rubrum as a valid species, which is proposed for listing as threatened under the U.S. Endangered Species Act. We synonymize P. rubrum under Pleurobema sintoxia —a common and widespread species found throughout the Mississippi River Basin. Further investigation of patterns of genetic variation in P. sintoxia identified a complex demographic history, including ancestral vicariance and secondary contact, within the Eastern Highlands. We hypothesize these patterns were shaped by ancestral vicariance driven by the formation of Lake Green and subsequent secondary contact after the last glacial maximum. Our inference aligns with demographic histories observed in other aquatic taxa in the region and mirrors patterns of genetic variation of a freshwater fish species (Erimystax dissimilis) confirmed to serve as a parasitic larval host for P. sintoxia. Our findings directly link species ecology to observed patterns of genetic variation and may have significant implications for future conservation and recovery actions of freshwater mussels. [ABSTRACT FROM AUTHOR]

During the RESOLVE project ("High‐resolution imaging in subsurface geophysics: development of a multi‐instrument platform for interdisciplinary research"), continuous surface displacement and seismic array observations were obtained on Glacier d'Argentière in the French Alps for 35 days in May 2018. The data set is used to perform a detailed study of targeted processes within the highly dynamic cryospheric environment. In particular, the physical processes controlling glacial basal motion are poorly understood and remain challenging to observe directly. Especially in the Alpine region for temperate based glaciers where the ice rapidly responds to changing climatic conditions and thus, processes are strongly intermittent in time and heterogeneous in space. Spatially dense seismic and Global Positioning System (GPS) measurements are analyzed applying machine learning to gain insight into the processes controlling glacial motions of Glacier d'Argentière. Using multiple bandpass‐filtered copies of the continuous seismic waveforms, we compute energy‐based features, develop a matched field beamforming catalog and include meteorological observations. Features describing the data are analyzed with a gradient boosting decision tree model to directly estimate the GPS displacements from the seismic noise. We posit that features of the seismic noise provide direct access to the dominant parameters that drive displacement on the highly variable and unsteady surface of the glacier. The machine learning model infers daily fluctuations and longer term trends. The results show on‐ice displacement rates are strongly modulated by activity at the base of the glacier. The techniques presented provide a new approach to study glacial basal sliding and discover its full complexity. Plain Language Summary: Alpine glaciers are a major component in the dynamic cryospheric environment. They are characterized by a multitude of processes occurring side by side, including but not limited to melt water flow, crevasse formation, and frictional basal sliding of the ice mass over the rigid and obstructive bedrock. Each of these processes generates distinctive acoustic signals that can be recorded by seismic instruments and the changing on‐ice motions are resolvable with Global Positioning System. Considering the rapidly changing glacial environment, there is an increasing need for reliable models to predict glacial dynamics to properly assess any associated hazard. Understanding basal sliding is of particular interest to this problem. Investigated here is how to overcome the challenge of describing glacier sliding using seismic signals since the records often contains multiple "loud" signals originating from associated surface processes within the glacier. To uncover specific processes occurring at the ice‐bedrock interface, we design a machine learning model to incorporate signals recorded on the glacier to predict the on‐ice surface motions. The results provide valuable insights into the spatiotemporal dynamics of an active Alpine glacier with the potential to contribute to a better understanding of the driving mechanisms of glacier sliding. Key Points: Seismic and Global Positioning System (GPS) data are examined to study physical processes controlling glacial basal motionDecision tree model uses beamforming catalog and statistical features of time series to constrain correlations with GPS recorded motionsModel features indicate glacial on‐ice velocity is modulated by basal motions [ABSTRACT FROM AUTHOR]

Seafloor hydrocarbon seepage is a natural fluid release process that occurs worldwide on continental shelves, slopes, and in deep oceanic basins. The Vestnesa sedimentary ridge in the eastern Fram Strait hosts a deep-water gas hydrate system that became charged with hydrocarbons ∼2.7 Ma and has experienced episodic seepage along the entire ridge until a few thousand years ago, when seepage activity apparently ceased in the west but persisted in the east. Although it has been documented that faults and fractures play a key role in feeding the seeps with thermogenic gases, the mechanisms controlling seepage periodicity remain poorly understood. Here we integrate high-resolution P-cable 3D seismic and Chirp data to investigate the spatial and temporal evolution of high-resolution fractures and fluid flow features in the west of the Vestnesa Ridge. We characterize sediment deformation using a fracture density seismic attribute workflow revealing two highly deformed stratigraphic intervals and associated small-scale pockmarks (

This paper reveals deglaciation palaeodynamics (Marine Oxygen Isotope Stage 2 [MIS 2]) in Poland and the southern Baltic Sea (SBS) development during marine transgression/regression phases (MIS 1) determined by a numerical modelling method. The introduced approach uses a high-level polynomial regression followed by the integral calculus of successive functions and an application of formulae. As a result, palaeogeographic relations from primary matrix transform instantly into palaeodynamics within a nested matrix. Accordingly, within 9 ka of the late Pleistocene, glacial recession dynamics increased by two orders of magnitude, from -8.5 m/yr between Leszno (L, 24 ka BP) and Poznań (Poz, 20-19 ka BP) phases, through several dozen (-37.2 m/yr, -60.6 m/yr, -90.7 m/yr) to the maximum average equalling -427.3 m/yr (max. -861.4 m/yr) between the Pomeranian (Pom, 17-16 ka BP) and the Gardno (G, 16.8-16.6 ka BP) phases. In turn, SBS coastline transgression and regression dynamics varied by three orders of magnitude. Since the Baltic Ice Lake (BIL, 10.5-10.3 ka BP) up to the Yoldia Sea (YS, 10-9.9 ka BP) regression was intense and equalled -56.8 m/yr (max. -128.7 m/yr), followed by marine transgression towards the Ancylus Lake (AL, 8.7-8.5 ka BP) at 21.43 m/yr through 9.30-2.20 m/yr during the Littorina Sea 1 and Littorina Sea 2 stages (LS1 and LS2, since 7.7 ka BP), eventually 0.51 m/yr in the last 6.05 ka. The 2m sea-level rise scenario projections indicate approx. 3400 km2 of land and 684,000 inhabitants face flood risk around 2150--2240 CE, with marine transgression dynamics expected to range from 23.9--38.2 m/yr. [ABSTRACT FROM AUTHOR]

Through the past few million years large ice sheets have repeatedly grown and disappeared on the Northern hemisphere. These are the Pleistocene glaciations. They are related to the changing solar heating of the Earth due to changes in Earth's orbit and axis of rotation. The climate response to these changes is highly non-trivial and non-linear, expressing the complex nature of the climate system. Many aspects of glacial cycles still need a convincing explanation, one particular mystery being the change from approximately 40 kyr (kilo year) glacial cycles to approximately 100 kyr cycles around 1 million years ago. This transition is called the middle Pleistocene transition (MPT). Here we review some conceptual models to explain the dynamics of glacial cycles and possible dynamical causes of the MPT. We especially focus on the well studied van del Pol oscillator as a conceptual model for the glacial cycles and propose that the MPT is a result of changes in frequency locking of the climate system to the astronomical forcing. This is compared to a recently presented model that relates the MPT to a transcritical bifurcation in the structure of a generic critical/slow manifold for a fast-slow dynamical system.

The Barents Sea Ice Sheet (BSIS) is a good palaeo-analogue for the present day West Antarctic Ice Sheet. Both were marine-based ice sheets, particularly vulnerable to ocean warming and sea-level rise. Understanding the BSIS ice dynamics and patterns of retreat since the Last Glacial Maximum (LGM) is useful in developing our knowledge of spatial and temporal variations during marine-based ice sheet retreat. While the western margins of the Barents Sea have been extensively studied, few studies have focused on the central regions, which hosted key ice stream tributaries and major ice domes and divides. Presenting a new high-resolution (5 m) bathymetric dataset, this glacial geomorphological study focuses on the Sentralbankrenna palaeo-glacial system in the central Barents Sea. A large number of grounding zone wedges, mega-scale glacial lineations and areas with tunnel valleys and palaeo-subglacial basins were identified. These form the basis for a six-stage reconstruction of ice stream retreat through deglaciation since the LGM. In reconstructing the retreat of the Sentralbankrenna Ice Stream, we document the rapid but highly spatially variable pattern of retreat of a marine-based ice sheet margin. The presence of several tunnel valleys and interconnected palaeo-subglacial basin systems indicates an abundance of meltwater, likely to have been stored and released through several discharge events, significantly influencing the ice stream margin dynamics. This study provides insight into the behaviour and dynamics of ice during the late stages of the BSIS deglaciation within the central Barents Sea, increasing our understanding of grounding line processes. [ABSTRACT FROM AUTHOR]

Authigenic 10 Be/ 9 Be ratios and 10 Be-fluxes reconstructed using the 230 Th xs normalization, proxies of the cosmogenic radionuclide 10 Be production rate in the atmosphere, have been measured in a sedimentary core from Baffin Bay (North Atlantic) spanning the last 136 ka BP. The normalization applied on the exchangeable (authigenic) 10 Be concentrations using the authigenic 9 Be isotope and 230 Th xs methods yield equivalent results strongly correlated with sedimentological parameters (grain-size and mineralogy). Lower authigenic beryllium (Be) concentrations and 10 Be/ 9 Be ratios are associated with coarse-grained carbonate-rich layers, while higher authigenic Be values are related to fine-grained felspar-rich sediments. This variability is due to: i) sediment composition control over beryllium-scavenging efficiency and, ii) glacial history that contributed to modify the 10 Be concentration in Baffin Bay by input and boundary scavenging condition changes. Most paleo-denudation rates inferred from the 10 Be/ 9 Be ratio vary weakly around 220 ± 76 tons.km −2 .yr −1 (0.09 ± 0.03 mm.yr −1 ) corresponding to relatively steady weathering fluxes over the last glacial cycle except for six brief intervals characterized by sharp increases of the denudation rate. These intervals are related to ice-surging episodes coeval with Heinrich events and the last deglaciation period. An average freshwater flux of 180.6 km 3 .yr −1 (0.006 Sv), consistent with recent models, has been calculated in order to sustain glacially-derived 10 Be inputs into Baffin Bay. It is concluded that in such environments, the authigenic 10 Be measured mainly depends on climatic effects related to the glacial dynamics, which masks the 10 Be production variation modulated by geomagnetic field changes. Altogether, these results challenge the simple interpretation of 10 Be-concentration variation as a proxy of Interglacial/Glacial (interstadial/stadial) cycles in Arctic and sub-Arctic regions. They rather suggest the effect of higher-frequency paleoclimatic changes and local glacial dynamics on 10 Be signature. [ABSTRACT FROM AUTHOR]

We present an account of the glacial dynamics from late Marine Isotope Stage (MIS) 3 to the Heinrich Stadial (HS) 1 on the Lofoten–Vesterålen margin, Northern Norway. This account is based on an analysis of the sedimentary stratigraphy on the upper slope close to the ice sheet grounding line at the continental shelf edge, and an analysis of the glacial morphology on the shelf areas. Our results point to a dynamic ice sheet that waxed and waned on the Lofoten–Vesterålen continental shelf from the late MIS-3, through the Last Glacial Maximum (LGM) and the HS 1. Glacigenic debris flows and deposition of laminated diamicts suggest that the ice sheet reached the shelf edge on several occasions. These are dated to ∼25.5 ka BP (HS3), between 21.1 and 21.7 ka BP, ∼19.5 ka BP, 15.6 ka BP and 14.4 ka BP (uncorrected 14 C ages). A contouritic sorted sand sediment unit that formed in a relatively warm interval during Late MIS-3 suggests that a strong Norwegian Atlantic Slope Current also developed during glacial interstadials implying that the oceanic circulation in the eastern Norwegian Sea was similar as today. The general pattern is that the ice sheet advanced onto the shelf during cold period with little influx of Atlantic Water to the Norwegian Sea and that it retreated toward the coast during intervals with higher temperatures and higher influx of warm Atlantic Water. The last ice advance to the edge of the continental shelf occurred during HS 1. [ABSTRACT FROM AUTHOR]

Glacial sediment yield results from glacial erosion and is influenced by several factors including glacial retreat rate, ice flow velocity and thermal regime. This paper estimates the contemporary subglacial erosion rate and sediment yield of Wanda Glacier (King George Island, South Shetlands). This work also examines basal sediment evacuation mechanisms by runoff and glacial erosion processes during the subglacial transport. This is small temperate glacier that has seen retreating for the last decades. In this work, we examine basal sediment evacuation mechanisms by runoff and analyze glacial erosion processes occurring during subglacial transport. The glacial erosion rate at Wanda Glacier, estimated using a numerical model that consider sediment evacuated to outlet streams, ice flow velocity, ice thickness and glacier area, is 1.1 ton m yr-1.

In this article, we introduce the Bayesian change point and variable selection algorithm that uses dynamic programming recursions to draw direct samples from a very high-dimensional space in a computationally efficient manner, and apply this algorithm to a geoscience problem that concerns the Earth's history of glaciation. Strong evidence exists for at least two changes in the behavior of the Earth's glaciers over the last five million years. Around 2.7 Ma, the extent of glacial cover on the Earth increased, but the frequency of glacial melting events remained constant at 41 kyr. A more dramatic change occurred around 1 Ma. For over three decades, the “Mid-Pleistocene Transition” has been described in the geoscience literature not only by a further increase in the magnitude of glacial cover, but also as the dividing point between the 41 kyr and the 100 kyr glacial worlds. Given such striking changes in the glacial record, it is clear that a model whose parameters can change through time is essential for the analysis of these data. The Bayesian change point algorithm provides a probabilistic solution to a data segmentation problem, while the exact Bayesian inference in regression procedure performs variable selection within each regime delineated by the change points. Together, they can model a time series in which the predictor variables as well as the parameters of the model are allowed to change with time. Our algorithm allows one to simultaneously perform variable selection and change point analysis in a computationally efficient manner. Supplementary materials including MATLAB code for the Bayesian change point and variable selection algorithm and the datasets described in this article are available online or by contacting the first author. [ABSTRACT FROM AUTHOR]

High-latitude marine sediment archives may contain information about the configuration and dynamics of former ice sheets, paleoclimate and the intensity of glacial erosion and uplift in catchment areas. Compiling information on the Late Cenozoic sediment packages along the NE Atlantic continental margin shows that large sediment volumes (c. 982 × 103 km3) were deposited during the Northern Hemisphere Glaciations (NHG), and that significant spatial and temporal variations in sediment input occurred during three distinct NHG Phases. NHG Phase I (2.7–1.5 Ma) was characterized by high sediment input to the trough mouth fan systems offshore Svalbard, suggesting strong glacial erosion and the development of large ice sheets over Svalbard. Comparatively moderate sedimentation and erosion rates are observed along the SW Barents Sea and the Norwegian margins during NHG Phase I. This indicates more restricted ice sheets over Fennoscandia compared to Svalbard, although periods of shelf edge glaciation most likely occurred. The most prominent overall margin development occurred during NHG Phase II (1.5–0.8 Ma), when recurrent large-scale, continental shelf edge, glaciations are suggested for the entire Eurasian Ice Sheets (EurIS). Compared to NHG Phase I, average sedimentation rates are three (91 cm/kyr) and two times higher (20 cm/kyr), respectively, in the Kara-Barents Sea-Svalbard Ice Sheet (KBSIS) region and the Fennoscandian/British-Irish Ice Sheet (FIS/BIIS) region. During NHG Phase III (0.8–0 Ma), sediment input decreases considerably (73%) along the marine margin of the KBSIS, while increasing significantly (62%) from the FIS/BIIS, in comparison to NHG Phase II. These estimates mark a major transition in the evolution of the EurIS, where the submergence below sea level of the Barents Sea region and the initiation of the Norwegian Channel Ice Stream are suggested to be key factors in this change. Furthermore, the submergence of the Barents Sea region affected ocean-atmosphere coupling and circulation which may have had a potential impact on global long-term climate change. • Glacial sediment volumes along the NE Atlantic marine margin of EurIS are compiled. • Large spatial and temporal shifts in sedimentation and erosion rates are identified. • EurIS extended to the NE Atlantic shelf edge already from the Early Pleistocene. • Paleogeographic changes impact ice sheet configuration and sediment distribution. [ABSTRACT FROM AUTHOR]

Spaceborne differential synthetic aperture radar (SAR) interferometry has been proven to be a powerful tool in monitoring environmental phenomena and, in particular, in observing glaciers and retrieving information about their surface topography and dynamics. In the last decade, the use of this technique has been successfully extended from space to ground-based observations as a tool for monitoring, on a smaller scale, single landslides, unstable slopes, and more recently, areas covered by snow but not yet glaciers. In this letter, the results of an experimental activity carried out to evaluate the potential of ground-based microwave interferometry to estimate the velocity of an unstable area belonging to a glacier is reported. This experiment demonstrated the possibility of remotely monitoring surface displacements of the monitored glacier up to a distance of about 3 km even if, due to the lack of ground truths on the observed area, the data interpretation must be carefully worked out. [ABSTRACT FROM PUBLISHER]

Abstract: The inner regions of the Antarctic continent are generally regarded as nearly aseismic, although microseismicity is known to occur beneath some outlet ice streams, related to the interaction between the fast flowing ice and the bedrock. Here we show the occurrence of unusual earthquakes beneath an Antarctic outlet glacier that share almost the same magnitude, pointing to the repeated rupture of a single asperity. These seismic events produce waveforms with very high similarity and uncommon spectrum and are tightly clustered in space but, unlike other reported instances of repeating earthquakes on a patch of the San Andreas Fault, they occur in frequent irregular swarms. Evidence locates these events at the rock–ice interface under the glacier, and shows the existence of stick–slip motion on a smaller scale than the large slow slip events detected by global seismographs. Seismic behaviour of large glaciers can presumably be connected to surges in ice motion. This study determines a little known environment for fracture dynamics studies, while also contributing to the understanding of the coupling processes between fast flowing glaciers and bedrock that influence ice stream evolution and stability. [Copyright &y& Elsevier]

New high-resolution multibeam bathymetry and sub-bottom profile datasets from Fingerdjupet are used for the first detailed geomorphological mapping of the seafloor in this area. The mapped landforms provide evidence for a palaeo-ice stream flowing in a southeasterly direction from Spitsbergenbanken into Fingerdjupet, merging with Bjørnøyrenna ice stream, and confirm a theorised palaeo-ice divide located along the bank. The combined landform records and acoustic stratigraphy allow a detailed reconstruction of the glacial dynamics during the last deglaciation. The withdrawal of the Fingerdjupet ice stream from Bjørnøyrenna was characterised by rapid retreat, punctuated by periods of stable ice marginal conditions. Five to six major ice margin stillstands and/or readvances associated with the last deglaciation are identified in the seafloor record and acoustic stratigraphy. During these events, large grounding zone wedges were deposited at the ice stream margin. The seabed geomorphology indicates that ice stream dynamics changed as the ice stream retreated from the trough onto the shallower bank. Here, numerous retreat moraines indicate that a grounded ice margin retreated slowly, with several minor stillstands, towards north-northwest. Several controls and/or drivers on the style of ice flow and retreat have been suggested, including catchment size reduction, sea level rise, bedrock topography, drawdown of bank ice and/or migration of the main ice divide over the bank. [ABSTRACT FROM AUTHOR]

A glacial environment is a unique setting that can alter human remains in characteristic ways. This study describes glacial dynamics and how glaciers can be understood as taphonomic agents. Using a case study of human remains recovered from Colony Glacier, Alaska, a glacial taphonomic signature is outlined that includes: (1) movement of remains, (2) dispersal of remains, (3) altered bone margins, (4) splitting of skeletal elements, and (5) extensive soft tissue preservation and adipocere formation. As global glacier area is declining in the current climate, there is the potential for more materials of archaeological and medicolegal significance to be exposed. It is therefore important for the forensic anthropologist to have an idea of the taphonomy in this setting and to be able to differentiate glacial effects from other taphonomic agents. [ABSTRACT FROM AUTHOR]