Seismic reflection data from Vincennes Bay, East Antarctica, provide the first insights into the Cenozoic evolution of the East Antarctic Ice Sheet (EAIS) in the Knox Coast. Long-distance seismic horizon correlation allows age estimates for the seismic stratigraphic framework constructed for the continental shelf. Preglacial depositional patterns reveal extensive fluvial plains on the continental shelf from the Late Cretaceous until the latest Eocene (similar to 34 Ma). These transitioned to glaciofluvial outwash plains during the late Oligocene. The earliest clear indication of ice sheets present on the Vincennes Bay continental shelf are two generations of large buried tunnel valley systems that developed during the Oligocene-Miocene Transition (similar to 24 Ma) and early Miocene during meltwater-rich glaciations originating in the Knox Coastal Plain. Glacially transported sediment wedges deposited at the end of the early mid-Miocene (>similar to 14 Ma) mark the beginning of steep glacial progradation of the continental shelf continuing through the Miocene and Pliocene. Ice sheet development from the late mid-Miocene to the Quaternary is likely driven by the Aurora Subglacial Basin via the Vanderford Glacier. This suggests a major reorganization of ice flow from the early glaciations of the Oligocene and early Miocene to the later development of modern configurations, established in the late mid-Miocene. Our results provide the first data of the Cenozoic development of the EAIS in Vincennes Bay and demonstrate the variability of ice flow conditions with past climatic changes.

This paper presents the results of a study of bedrock samples obtained by drilling through 541 m of ice in north-western Princess Elizabeth Land. The drilling was aimed to decipher the geological nature of a high-amplitude linear magnetic anomaly running parallel to the coast for over 500 km from Princess Elizabeth Land to Mac. Robertson Land. The rock obtained by drilling is a melanocratic orthopyroxene-hornblende-biotite crystalline schist (mafic granulite) with a protolith age of similar to 970 Ma. Two metamorphic events are identified: early metamorphism with an age of similar to 890 Ma and peak parameters of 740-780 degrees C and 4.0-4.5 kbar; and late metamorphism with an age of similar to 800 Ma and parameters of about 650 degrees C and similar to 3 kbar. According to the data obtained, the linear magnetic anomaly can be interpreted as an island arc that was accreted to Antarctica during the assembly of Rayner Province.

Abstract Mafic-ultramafic intrusions represent the primary source of global scandium (Sc) resources worldwide. These intrusions typically originate from fertile mantle sources in arc systems. While fluid- and melt-driven metasomatism are widely recognized as crucial mechanisms for Sc enrichment in the mantle, key aspects, including the precise composition of these metasomatic agents and their operating conditions remain poorly constrained. To address these knowledge gaps, we conducted a comprehensive investigation of Sc enrichment and release using clinopyroxene and orthopyroxene chemistry from charnockites and mafic granulites in East Antarctica’s Prydz Bay Belt. We reveal a multi-stage Sc evolution pathway within the accretionary belt that is initiated by dehydration of carbonate rocks, generating reduced carbonatite melts which trigger mantle metasomatism and significantly enrich Sc in the pyroxene. This enrichment is followed by post-peak decompression melting at 800-1000 °C and 6.5-12.8 kbar, which triggers metasomatism by an oxidized silicate melt, facilitating Sc release from both orthopyroxene and clinopyroxene. The subsequent arc accretion stage involves interaction with an external, oxidized, and likely phosphorus-rich aqueous fluid, leading to Sc release. The findings of Sc-rich pyroxene in mafic granulite and charnockite, together with the presence of CO₂-rich fluid inclusions in East Gondwana (Antarctica), collectively indicate that scandium enrichment may be a regional event. This study provides further implications for the exploration of Sc deposits in metamorphic rocks.

A giant submarine landslide in front of the Wilkes subglacial basin along the Cook continental margin—one of the least explored areas on Earth—has been documented for the first time. This area is critical to understanding the stability of one among the most vulnerable sectors of the Antarctic Ice sheet to climate and ocean warming. It is named as Cook mega-slide complex (CMSC), which occurred in the early Pliocene according to the seismic interpretation correlated to the IODP Exp 318 sites. The giant submarine landslide is well imaged on the seismic profiles and exhibits various kinematic indicators with the basal glide planes and original headwall scarps. It affected the area of c. 22, 686.5 km2, approximately 3399 km3 of sediments evacuated from the continental margin. With a scale similar to Storegga Slide on the Norway margin, the size of the CMSC is mostly likely the largest submarine landslide ever discovered around the Antarctic margin. We propose that glacial isostatic adjustment and glacial outburst floods caused by the East Antarctic Ice Sheet (EAIS) retreat lead to the formation of the large slides and create the condition for slope instability and erosion. The development and collapse of peripheral bulge has been firstly observed from Antarctic margin, associated with the glaciation and subsequent deglaciation of the EAIS, led to a distinct spatial variation in sea level changes and further affected the deposition on the slope. Our results yield intriguing insights into the relationship of stratigraphic evolution, submarine landslides, and past EAIS instabilities throughout the warm periods of the late Miocene-Pliocene, and thereby provide important constraints for ice sheet modeling and sea level prediction.

The Antarctic bed demonstrates complex behaviour comprising alternating warm- and cold-based areas. However, the distribution of warm- and cold-based areas, basal melting rates, and the structure and age of the basal ice are not yet fully known. In the 2023-2024 season, we drilled an access borehole through 541 m thick ice at Princess Elizabeth Land, 28 km south of the coast. Temperature measurements at the bottom of the borehole revealed a cold underlying base despite a warm-based interface being predicted in advance as the most likely estimate. Our results imply that the Antarctic base can be locally colder than currently assumed, and that thermal models, especially basal boundary conditions, should be carefully specified and provided with the confirmed input data.

A giant submarine landslide complex is reported on the George V margin of East Antarctic continental rise. Such landslides are imaged on seismic profiles that display evidence of basal glide planes and headwall scarps. A longitudinal seismic transect, and correlation to nearby drill sites suggest the slide was formed after the early Pliocene. To our knowledge, it is the largest submarine landslide ever identified on the Antarctic margin, with approximately 2,300 km 3 of sediments evacuated from the shelf. We propose potential triggers for this slide, including weak layers, fluid and isostatic rebound following ice sheet retreat, although hypothesis relating to the processes has to be tested by direct stratigraphic data. Given the size of the landslide, an improved understanding of whether it was formed during a single event or more gradually during a prolonged interval is critical to evaluate whether Antarctic submarine geohazards may exist in a rapidly changing climates.

The East Antarctic Ice Sheet (EAIS) has long been assumed to remain relatively stable under current climatic forcing. Recently, however, this assumption has been challenged by the observation of increased ice mass loss, improved subglacial topography data, and extensive geological and geophysical data of past glacial change from the Sabrina Coast. Glacial-marine sediments deposited on the continental shelf, slope, and rise record past ice sheet expansion and retreat periods that have occurred since the onset of Southern Hemisphere glaciations. The Vanderford Glacier is the main glacial outlet in Vincennes Bay (eastern Mawson Sea shelf), which together with the Totten Glacier drains the large Aurora Subglacial Basin.We use deep-penetrating seismic reflection data collected during the RV Polarstern Expedition PS141 (EASI-3) in early 2024 combined with existing data to construct a seismic stratigraphic model of the continental shelf, slope, and rise in Vincennes Bay. The newly acquired seismic data reveal pre-glacial sedimentary strata and glacially-transported sequences on the continental shelf and slope in a previously unmapped area near the Vanderford Glacier. We analyze pre-glacial and glacial sedimentation processes on the East Antarctic continental shelf in this region, which so far remained poorly constrained. This allows us to decipher dominant phases of early Oligocene to Pleistocene EAIS development in this sector.Long-distance seismic horizon correlation with deep-sea scientific drill records from DSDP, ODP, and IODP sites in the northern Mawson Sea, Prydz Bay, and offshore Wilkes Land provides age estimates for the seismostratigraphic sequences on the continental shelf. The earliest clear indications of grounded ice advancing onto the middle continental shelf are inferred in the Early Miocene (~24-14 Ma) from buried subglacial channel systems. The middle shelf consists of older preglacial sequences of Late Cretaceous to Late Miocene age and is overlain by a much younger (Quaternary?) gigantic grounding zone wedge. The outer continental shelf is dominated by prograding glacially-transported sequences of inferred Late Miocene to Pliocene age (14-5 Ma), indicating repeated advances of grounded ice with a high sediment influx from the hinterland. In contrast to the neighbouring Totten Glacier of the Sabrina Coast, the distribution of glacial sedimentary features across sequences suggests that the EAIS was more stable in the Vincennes Bay region, highlighting how differently these two systems might have reacted to changing conditions.

We present Bedmap3, the latest suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60 °S. Bedmap3 incorporates and adds to all post-1950s datasets previously used for Bedmap2, including 84 new aero-geophysical surveys by 15 data providers, an additional 52 million data points and 1.9 million line-kilometres of measurement. These efforts have filled notable gaps including in major mountain ranges and the deep interior of East Antarctica, along West Antarctic coastlines and on the Antarctic Peninsula. Our new Bedmap3/RINGS grounding line similarly consolidates multiple recent mappings into a single, spatially coherent feature. Combined with updated maps of surface topography, ice shelf thickness, rock outcrops and bathymetry, Bedmap3 reveals in much greater detail the subglacial landscape and distribution of Antarctica’s ice, providing new opportunities to interpret continental-scale landscape evolution and to model the past and future evolution of the Antarctic ice sheets.

This study seeks to demonstrate the relationship between magnetic anomalies and geological structure of Precambrian complexes of the Bunger Oasis and Highjump Archipelago, East Antarctica. Aeromagnetic data effectively maps geological units, revealing distinct magnetic signatures for Neoarchean and Palaeo Mesoproterozoic terrains. This provides the possibility of significantly improving existing geological maps, particularly in poorly mapped areas like the Highjump Archipelago. Magnetic anomaly intensity and strike correlate with rock composition and regional structural trends, enabling better differentiation of lithological units like magnetic metapelites and non-magnetic metapsammites. Tilt derivative calculations enhance structural mapping by linking magnetic sources to specific rock suites. As an example, a prominent northeast-striking belt of positive magnetic anomalies marks a key boundary between Archean and Mesoproterozoic complexes. Variations in the belt’s strike suggest complex tectonic history, including potential fault contacts. Intrusive bodies exhibit complex magnetic characteristics. The Paz Cove intrusion displays a negative anomaly likely due to reversed remanent magnetization, while the Algae Lake intrusion has both positive and negative anomalies reflecting varying rock compositions. The Gabbro intrusions in the northeastern part of the Highjump Archipelago correlate with positive anomalies, while the intense negative anomaly over the Kashalot Island gabbroic intrusion suggests reversed magnetization. This study aims to produce a structural (tectonic) map of the Bunger Oasis and Highjump Archipelago by analyzing magnetic anomaly data collected by an unmanned aerial vehicle during the 69th RAE, combined with existing geological information for the area. The study highlights the value of UAV aeromagnetic surveys for detailed geological mapping in challenging environments, providing crucial insights into East Antarctica’s Precambrian history.

As a result of a study of igneous rocks of the basalt - andesite series, dredged on the Shaka Ridge in the South Atlantic, it was found that they differ from the basalts of mid-ocean ridges and ocean islands, and have an age of 183.8 ± 2.2 Ma, comparable to the time of manifestation of the Karoo-Maud mantle plume in central Gondwana. Geochemical and Sr–Nd–Pb isotopic features of the studied igneous rocks show their similarity with the Jurassic mafic complexes of the Ferrar province in Antarctica and the Falkland Islands, formed during the intrusion of the Karoo-Maud plume and under the influence of paleo-Pacific subduction. However the supply of ice rafted debris into the study area due to ice transportation is considered unlikely. Based on the all data obtained, it was concluded that the Shaka Ridge is a continental block that was moved during the opening of the South Atlantic in the Early Cretaceous-Early Miocene from the continental margin of Africa along an extended transform fault into the present Bouvet triple junction area.

AbstractThe intrusion of relatively warm water onto the continental shelf is widely recognized as a threat to Antarctic ice shelves and glaciers grounded below sea level, as enhanced ocean heat increases their basal melt. While the circulation of warm water has been documented on the East Antarctic continental shelf, the modes of warm water transport from the deep ocean onto the shelf are still uncertain. This makes predicting the future responses of major East Antarctic marine-grounded glaciers, such as Totten and Ninnis glaciers, particularly challenging. Here, we outline the key role of submarine canyons to convey southward flowing currents that transport warm Circumpolar Deep Water toward the East Antarctic shelf break, thus facilitating warm water intrusion on the continental shelf. Sediment drifts on the eastern flank of the canyons provide evidence for sustained southward-directed flows. These morpho-sedimentary features thus highlight areas potentially prone to enhanced ocean heat transport toward the continental shelf, with repercussions for past, present, and future glacial melting and consequent sea level rise.

The paper is based on additional studies of mineral inclusions in the accretion ice sampled by deep drilling at Vostok Station in central Antarctica. The studies include X-ray microtomography of two mineral inclusions with identification of their mineral composition; analysis of clay minerals in the soft aggregate of the largest inclusion; and geochronological study of zircon grains. X-ray microtomography shows intact morphology of the inclusions in the ice core and their internal texture. The soft aggregate of the largest inclusion is characterized by the dominance of illite, intermediate concentrations of chlorite and small amounts of kaolinite. A notable feature is the absence of mixed-layer minerals typical of Antarctic coastal areas. The most valuable information is derived from new geochronological data and their integration with previous dating data. The detrital zircon U-Pb ages show strong probability peaks between 900 and 1100 Ma, while the detrital monazite ages are clustered between 1250 and 1450 Ma. Both of these age intervals correspond to the Rayner Orogeny.

The paper presents a review of the studies carried out in the area of the subglacial Lake Vostok (East Antarctica) to date. They include geophysical, glaciological, geodesic, and geological investigations. The most important geophysical investigations were carried out by the Polar Marine Geosurvey Expedition. They included reflection and refraction seismic, and also radio-echo sounding. The major contribution to the study of this region was made by American researchers, who in the 2000/01 field season performed a complex airborne geophysical survey on a regular network. Their work included magnetometric, gravimetric, and radio-echo sounding measurements. All the research conducted found that the water surface area is 15 790 km², and its altitudinal height changes from –600 to –150 m. The average depth of Lake Vostok is 400 m, and the maximum marks reach 1 200 m. The water body volume is estimated at 6 100 km³. There are 11 islands in the lake, and their total area is 365 km². In addition, 56 isolated subglacial water bodies were found around the lake. A special section is devoted to a review of mathematical models of heat and mass transfer processes in the glacier and water movement in Lake Vostok.

— This article includes a review of the structure and evolution of the Antarctic Earth crust (the Antarctic continent and the Southern Ocean) from the Archean to the Late Cenozoic, accompanied by the sketch of Antarctic tectonic provinces. It is based on the long-term research and preparation of the second edition of the Tectonic Map of the Antarctica at a scale of 1 : 10 000 000 with a detailed explanatory note in the International Commission for the Geological Map of the World. In the course of the work a large volume of geological and geophysical data of Russian Antarctic expeditions and expeditions of other countries were combined, analyzed, and interpreted, first of all, the data of geochemical and geochronological studies of rock specimens from outcropped regions and numerous geophysical surveys in the Southern Ocean. The structure and tectonic history of the Archean cratons and Proterozoic orogens of East Antarctica (with indication of the controversial issues of Precambrian evolution), the orogens of the Pacific margin, intraplate fold systems, continental margins, and the early sea floor spreading are considered.

Targeted bedrock sampling was carried out on Princess Elizabeth Land (30 km south of the coast, at 69.585591° S; 76.385165° E) by drilling through 545 m thick ice. The borehole was drilled using a new, modified version of the cable-suspended Ice and Bedrock Electromechanical Drill (IBED) designed by the Jilin University (China) and under a joint scientific project between VNIIOkeangeologia, Jilin University and China University of Geosciences (Beijing). The drill site is located on the axis of a high-amplitude linear magnetic anomaly that runs parallel to the coast for more than 500 km from Princess Elizabeth Land to Mac. Robertson Land. In the next Antarctic season, borehole geophysical logging will be conducted including temperature measurements for geothermal heat flux calculations.

— The study of Re–Os isotopic systematics of the Mesozoic magmas in East Antarctica and its comparison with Sr–Nd–Pb–Os published data allowed us to reveal the main features of Antarctic magmatism associated with the activity of the Karoo–Maud (Dronning Maud Land (DML), Karoo and Ferrar provinces) and the Kerguelen (Lambert rift area) plumes. It is shown that a melt source of the 180-Ma Karoo–Maud plume could be enriched lithospheric mantle. Variations of the 187 Os/ 188 Os ratio in the range of 0.1242–0.1426 characterize almost all types of melts in the Karoo and DML provinces, including both high- and low-Ti magmas as well as high-Mg ferropicrites produced by melting of mantle pyroxenite. This observation is consistent with previous assumption that magmas derived from pyroxenite mantle at the initial stage of plume impact represented melts of deep lithospheric fragments of ancient Gondwana paleocontinent that were entrapped by plume. Thereby, mantle heterogeneity recorded in the Nd–Pb–Sr isotopic compositions of the basalts is not expressed in the systematic variations of Re–Os isotope system. The magmatic source of the basalts of the Ferrar province differs from the source of Mesozoic magmatism in the Karoo and DML provinces by great variations in the 187 Os/ 188 Os ratio: from 0.1 to 0.31, and by the lower osmium contents, with limited variations of other isotopic systems, indicating an admixture of enriched EM-II source. This is consistent with inferred subduction reworking of the mantle of the western Antarctic margin (Sushchevskaya et al., 2022). Ultramafic picritic magmas from the Lambert Glacier area are characterized by a radiogenic osmium isotopic composition: 187 Os/ 188 Os 0.1582–0.2388. Source of these magmas could be ancient depleted mantle, which later experienced mantle metasomatism due to the multiple interactions with fluid-saturated melts. Picritic melts of the paleorift zone of the Lambert Glacier are close to a magma source of the Karoo and DML provinces in terms of Sr-Nd isotopic composition, but differ in more radiogenic lead.

One of the key components of this research has been the mapping of Antarctic bed topography and ice thickness parameters that are crucial for modelling ice flow and hence for predicting future ice loss and the ensuing sea level rise. Supported by the Scientific Committee on Antarctic Research (SCAR), the Bedmap3 Action Group aims not only to produce new gridded maps of ice thickness and bed topography for the international scientific community, but also to standardize and make available all the geophysical survey data points used in producing the Bedmap gridded products. Here, we document the survey data used in the latest iteration, Bedmap3, incorporating and adding to all of the datasets previously used for Bedmap1 and Bedmap2, including ice bed, surface and thickness point data from all Antarctic geophysical campaigns since the 1950s. More specifically, we describe the processes used to standardize and make these and future surveys and gridded datasets accessible under the Findable, Accessible, Interoperable, and Reusable (FAIR) data principles. With the goals of making the gridding process reproducible and allowing scientists to re-use the data freely for their own analysis, we introduce the new SCAR Bedmap Data Portal (https://bedmap.scar.org, last access: 1 March 2023) created to provide unprecedented open access to these important datasets through a web-map interface. We believe that this data release will be a valuable asset to Antarctic research and will greatly extend the life cycle of the data held within it. Data are available from the UK Polar Data Centre: https://data.bas.ac.uk (last access: 5 May 2023​​​​​​​). See the Data availability section for the complete list of datasets.

The Gramberg All-Russia Research Institute for Geology and Mineral Resources of the World Ocean (FSBI VNIIOkeangeologia) carries out a wide range of research in the fields of geology, engineering geology, geophysics, and geochemistry. The specialists of the institute perform studies using most-up-to-date equipment in several directions, including the study of the geology and mineral resources of the Arctic, Antarctic and the World Ocean. The geological and tectonic maps and atlases of the Eurasian sector of the Arctic shelf and adjacent deepwater zones of the Arctic Ocean have been compiled. This allow one to recognize the rift-related basins on the East Arctic shelf of Russia, and the conjunction areas of the Lomonosov, Gakkel, and Mendeleev oceanic ridges with the Eurasian continental margin. A comprehensive interpretation of geological and geophysical data has revealed features of the tectonics of the Amerasian Basin, which indicate that the evolution of the basin structures took place under conditions of continental rifting. One of the main scientific conclusions drawn at the preparation of the Submission of the Russian Federation in respect of the continental shelf boundary in the Arctic Ocean is the proof of the continental nature of the structures of the Central Arctic Rise Complex: the Lomonosov Ridge, Podvodnikov Basin, Alpha–Mendeleev Rise, Chukchi Basin, and Chukchi Borderland. This conclusion is confirmed by the characteristics of the main layers of the Earth’s crust in the above structures. A geodynamic model of the evolution of the Precambrian complexes of East Antarctica has been developed and the main tectonic provinces of Antarctica have been distinguished. A universal seismostratigraphic model of sedimentary basins has been developed for the marginal seas of East Antarctica. An important area of research in Antarctica was the study of the subglacial Lake Vostok. When studying the history of the formation of sulfide mineralization, it was found that the discharge of hydrothermal ore-bearing solutions most often occurs continuously, and only the intensity of the ore formation process changes with time. The possibility of formation of massive sulfide ore volumes additional to the main surface deposit due to metasomatic replacement of host igneous rocks has also been established.

AbstractA 198.8 m deep borehole was drilled through ice to subglacial bedrock in the northwestern marginal part of Princess Elizabeth Land, ~12 km south of Zhongshan Station, in January–February 2019. Three years later, in February 2022, the borehole temperature profile was measured, and the geothermal heat flow (GHF) was estimated using a 1-D time-dependent energy-balance equation. For a depth corresponding to the base of the ice sheet, the GHF was calculated as 72.6 ± 2.3 mW m−2and temperature −4.53 ± 0.27°C. The regional averages estimated for this area based, generally, on tectonic setting vary from 55 to 66 mW m−2. A higher GHF is interpreted to originate mostly from the occurrence of metamorphic complexes intruded by heat-producing elements in the subglacial bedrock below the drill site.