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Studies on the demersal fish composition of the East Antarctic nearshore region are very scarce due to the harsh physical geography of the East Antarctic region, which is covered in ice and snow year round, leading to a scarcity of scientific surveys. Based on the data from the bottom trawl survey conducted by the 37–38th Chinese National Antarctic Research Expedition (CHINARE) program in the Cosmonaut Sea, East Antarctica, the species of demersal fishes were identified, and the demersal fish composition and the characteristics of depth distribution were examined and analyzed. The basic biological information of highly abundant species was analyzed. The results from 97 individuals sampled within 30–60° E, south of −65° S, indicate that the fishes belong to 5 orders, 11 families, 19 genera, and 23 species. Most of the species are found in Myctophidae and Bathydraconidae, and the most common species is Macrourus whitsoni (Macrouridae). Macrourus whitsoni and Prionodraco evansii have a high abundance in the survey. Macrourus whitsoni has body lengths of 144–662 mm and body weights of 17.3–1425.1 g, and Prionodraco evansii has body lengths of 90.18–134.33 mm and body weights of 4.9–20.7 g. The length–weight relationships for Macrourus whitsoni and Prionodraco evansii are y = 0.00002 x 2.748 and y = 0.000006 x 3.353 , respectively. All the Macrourus whitsoni samples were found in waters deeper than 1000 m, with the highest number of individuals captured at depths of 1500–2000 m. Prionodraco evansii was found only at stations less than 250 m deep. These results complement the demersal fish composition and distribution data of the Cosmonaut Sea, East Antarctica. These data can provide valuable basic information for characterizing regional assemblages and delineating zoogeographic boundaries. [ABSTRACT FROM AUTHOR]

SUMMARY Antarctica represents a key component in the investigation of the geological history and reconstruction of the supercontinents Rodinia and Gondwana. Remnants of the formation and disintegration of these ancient land masses can be found, although great uncertainties remain in the location of tectonic boundaries beneath the ice sheet of Antarctica due to general lack of outcrops and the limited amount of geological data. Airborne and space measurements are the only possibility to obtain comprehensive spatial data coverage for geological studies in the remote polar areas. More than 100 000 line kilometres of airborne geophysical data, including radio echo sounding, gravity and magnetic data, were acquired over an area of 1.2 million square kilometres in the centre of Dronning Maud Land (DML) over four austral summer campaigns between 2001 and 2005. The data are presented here as compilations of homogeneous topographic and gravity data for the DML region, ranging from 14°W to 20°E and from 70°S to 78.5°S. With respect to older airborne geophysical investigations in DML, up to 85 per cent of the gravity data cover unexplored regions. Analyses of the maps of topography and gravity anomalies, by filtering and isostatic analysis, reveal information about geological and tectonic structures in DML. Different gravity maps provide hints for the general tectonic fabric of the area. For the first time the southern boundary of the continent-ocean boundary formed during the Jurassic dispersal of Gondwana is identified. Especially the mountain range in DML is most likely not in isostatic balance. The area is still uplifting as a consequence of glacial rebound. Interpretations of the Jutul-Penck Graben as failed Jurassic rift system can be confirmed by the gravity inversion. Thinned continental crust compared to the surrounding geological units strongly support this hypothesis. Besides on other interpreted anomalies, the data show a gravity structure, which starts approximately at 73.25°S/006°E and strikes in southwestern direction. We speculate that this pattern represents the suture zone [eastern termination of East African-Antarctic Orogen (EAAO)] between southern Africa and the cratonic part of Antarctica. [ABSTRACT FROM AUTHOR]

The article presents a thermo-hydrodynamic modelling study of the low-elevation blue-ice areas in Antarctica where significant amounts of subsurface liquid water during summer can be contained and absorption of shortwave radiation can be experienced. The study of the phenomenon is using the existing 2-D (x-z) model and is improved by changing the optical and thermal boundary conditions together with the optical attenuation coefficient. Significant effect of spatial variability of snow on subsurface melting has been found out.

The article examines the composition, structure and deformation of amber ice as well as its influence on Rhone Glacier's behaviour in the McMurdo Dry Valleys in Antarctica. The basal ice sequence of the cold-based glacier was investigated using isotopic and solute chemistry data. The study identifies three different ice facies including englacial, amber and stratified. The analysis of stratified facies shows an isotopic signature which indicates melt then refreeze processes and is most likely associated with apron entrainment. It was found out that impurities in the amber ice has prolonged contact with the bed and that depleted isotopic signature is consistent with ice formed during a cooler period.

The article focuses on the determination of basal conditions for Pine Island and Thwaites Glaciers in West Antarctica. Study shows strong basal melting in upstream areas where the ice flow is fast and the basal shear stress is large. It was found out that both glaciers have mixed bed conditions with extensive areas of bedrock and weak till. The ice-stream model reveals a strong sensitivity to the assumed bed model. The results offers compatibility with limited observational constraints and theoretical work indicating an upper bound on maximum basal shear stress.

The article focuses on the velocity field of Brunt Ice Shelf and Stancomb-Wills Ice Tongue in East Antarctica. It notes that the velocity is developed using the automated feature-tracking techniques on RADASTAT-1 imagery from the 1997 Antarctica Mapping Mission-1 (AMM-1) and 2000 Modified Antarctic Mapping Mission (MAMM). The velocity field and radar images investigation shows divergence of contemporary flowlines from relict flow stripes along a portion of Stacomb-Wills Ice Tongue. The velocity field was used in reconstructing the former stripe configuration.

Data from New Zealand and northern Victoria Land, Antarctica, indicate that the Cambrian Takaka Terrane intra-oceanic arc/backarc assemblage and the Bowers Terrane intra-oceanic arc/back-arc assemblage were accreted to the Gondwana margin by the Late Cambrian. Compelling similarities between the arc rocks and the immediate post-arc sediments firmly place the two regions in the same tectonic framework and imply close paleogeographic proximity. Currently, the Ross Orogen is thought to be the result of sinistral oblique convergence with west-directed subduction, and accretion of the arc assemblages is attributed to closure of backarc basins. Syntectonic fluvial conglomerates in both regions attest to the development of fluvial systems draining both the accreted arc and the contemporaneous continental margin arc. Trilobite faunas indicate that fluvial sedimentation commenced earlier in New Zealand than in northern Victoria Land. In the context of the widely accepted sinistral oblique convergence model, these data suggest an original position for New Zealand to the south of northern Victoria Land, probably in the region of the southern Ross Sea. [ABSTRACT FROM AUTHOR]

Abstract: The Ferrar Large Igneous Province forms a linear belt for 3500 km along the Transantarctic Mountains, and as a geochemical province extends into southeastern Australasia. The principal components of the Ferrar are: intrusive — Ferrar Dolerite sills and dikes, and Dufek intrusion; pyroclastic — the Prebble, Mawson and Exposure Hill Formations; effusive — the Kirkpatrick Basalt. In terms of the three dimensional architecture of the Ferrar, a range of “facies” can be recognized in each of the principal components. The Ferrar province was initiated with a major episode of phreatomagmatism leading to formation of tephra cones and associated deposits, and near-surface vent structures. Activity switched to predominantly quiet effusion of alternating thick flood basalt flows and thin pahoehoe lobes and flows. Intrusive bodies were emplaced early, given the occurrence of dolerite clasts in tuff–breccias, but most sills were probably intruded after accumulation of extrusive rocks. Pre-existing rift structures played a major role in controlling the transport and distribution of the Ferrar magmas and the apparent centers of extrusive activity. The associated paleohydrology controlled the eruption styles. [Copyright &y& Elsevier]

The West Antarctic rift system differs from other volcanically active rift systems in two unusual respects: (1) the rift floor lies 1000-2000 m lower in elevation than others, and (2) four interior ice-filled troughs extend between 1500 m and 2555 m below sea level. Two troughs are more than twice the depth of Lake Baikal, the world's deepest lake. The Marie Byrd Land dome, by contrast, compares closely with the intra-rift Kenyan and Ethiopian domes in the East African rift. Comparisons between these rift systems suggest (1) that the West Antarctic interior is relatively cool and volcanically inactive, (2) that there is likely to have been an episode of extension during Neogene time in the deep interior basins, and (3) that dome uplift and basin subsidence have greatly changed the West Antarctic landscape over the past 25 m.y. [ABSTRACT FROM AUTHOR]

Based on the horizon of β activity and the density profiles, recent accumulation rate at Dome A, Antarctica is calculated to be 0.023 m water equivalent per year. This value is comparative to the accumulation rates deduced from the other inland sites of Antarctica. Clear-sky precipitation (or diamond dust) dominates the total precipitation at Dome A region. We speculate Dome A as a potential site to discover the oldest ice in Antarctica due to its tremendous ice thickness (>3000 m), extremely low accumulation rate, and low ice velocity. [ABSTRACT FROM AUTHOR]

The history of Lake Vostok, the huge East Antarctic subglacial lake, is critical to the unique biota expected in this extreme environment. One theory is that the lake existed prior to the mid-Miocene glaciation of the continent at around 15 million years ago, survived the subsequent period of ice growth intact, and then remained relatively stable beneath its thick ice cover to the present day. The alternative is that the lake was formed by subglacial water flow into an existing and/or glacially eroded trough after the ice sheet reached its present configuration. Here, the onset of persistent ice cover in Antarctica is reviewed and a simple model for continental ice growth discussed. This information is used to argue against the preglacial origin of subglacial lakes. Lake Vostok is large because ice flows essentially perpendicular to the trough's long axis, permitting the slopes of the ice surface and the ice-water interface to be low. During the onset of glaciation ice flow across Lake Vostok would have been more akin to flow across an ice marginal trough such as the Astrolabe Subglacial Basin, which holds the thickest ice in Antarctica: 4776 m where the bed is over 2 km below the sea level. Hence, regardless of whether Lake Vostok was a lake prior to glaciation, its trough is likely to have been occupied by grounded ice during the period of ice growth. Although the lake is stable today, its size and extent will be affected by ice sheet changes that occur over glacial-interglacial cycles. Such changes are reviewed and the potential consequences for the lake's volume are discussed. [ABSTRACT FROM AUTHOR]

Abstract: In the coastal mountains of Marie Byrd Land, Antarctica, there is a juxtaposition of ice moulded landforms at lower altitudes and upstanding summits with weathered surfaces bearing tors. This paper uses geomorphological mapping and exposure dating to test two hypotheses commonly used to explain such a landscape contrast: either the pattern reflects contrasts in glacial erosion related to the basal thermal regime beneath a former ice sheet or it represents a periglacial trimline marking the upper limit of ice cover during the Last Glacial Maximum (LGM). Cosmogenic nuclide measurements on erratics show that the mountains were covered by ice on several occasions, most recently during the LGM. Similar measurements on bedrock show that fragile landforms on weathered surfaces survived many glaciations. Nuclide concentrations in bedrock indicate both that subglacial erosion is insignificant and that ice-free periods of periglacial weathering are longer at higher elevations. We conclude that the pattern of landscape modification reflects both topographically controlled contrasts in the basal thermal regime of overriding ice and the longer exposure to periglacial conditions at higher elevations. In addition, the combination of nuclide data and the wider pattern of striations shows that the LGM ice cover was thinner than predicted by ice sheet models assuming equilibrium conditions, that ice sheet thinning has occurred from 10,400 years ago to the present, and that regional flow by overriding ice has been replaced by radial ice flow from local glaciers centred on individual mountain massifs. [Copyright &y& Elsevier]

Ice thickness in West Antarctica at the Last Glacial Maximum (LGM) is poorly known, yet is key information for understanding ice streams and interpreting ice cores. Although trim lines, moraine limits, and exposure-age dating provide geologic constraints on ice thickness near the Transantarctic Mountains and in Marie Byrd Land, lack of exposed bedrock hampers traditional geologic methods in a central, ∼2 × 106 km² region. Here we infer ice-sheet thickness changes in the central Ross Sea Embayment by using a transient ice-flow model to find combinations of accumulation-rate and ice-sheet thickness histories that match the depth-age relationship and the measured layer-thickness pattern in the Siple Dome ice core. After we reject unreasonable accumulation-rate histories, the remaining history pales indicate thinning of 200–400 m since the LGM. Our estimate is lower than previous reconstructions that were constrained by geologic evidence from the Transantarctic Mountains and by marine data from the Ross Sea floor, which indicate that a grounded ice sheet extended to the continental shelf margin during the last glacial period. Low surface elevations in the central Ross Sea Embayment during the LGM do not preclude thicker ice along its boundaries. However, if this grounded ice sheet came over 1000 km from interior West Antarctica, as is usually assumed, then it had very low surface slope, requiring a very slippery bed. Alternatively, the grounded Ross Sea ice might have flowed from the Transantarctic Mountains and western Marie Byrd Land. [ABSTRACT FROM AUTHOR]

Surficial deposits in eastern and central Wright Valley, Antarctica, record multiple inland incursions of grounded ice from the Ross Sea Embayment. Glacial geologic mapping, coupled with 42 AMS 14C dates of lacustrine algae and 10 40Ar/39Ar dates of basalt erratics, indicate westward ice expansion at least eight times during the Pliocene and Quaternary. The most extensive westward incursion resulted in an advance of at least 21 km beyond the margin of present-day Wright Lower Glacier, accompanied by ice thickening of ≥500 m at the location of the present-day Wilson Piedmont Glacier in the eastern valley mouth. Large proglacial lakes and glaciolacustrine sedimentation coincide with at least some of these advances. [Copyright &y& Elsevier]

Among the major ice streams that drain West Antarctica, Kamb Ice Stream (formerly called Ice Stream C) is unique in that it stagnated ∼150 yr ago, but its former fast-flow conditions are virtually unknown. Here we present surface-based radar profiles of the ice stream's undulating internal stratigraphy, which records these conditions. Our analysis of the profiles indicates that prestagnation flow velocities, averaged over a period <740 yr, exceeded 350 m·yr-1 in the trunk of the ice stream. This velocity constraint would be lower if the ice had been thickening (higher if thinning), but suggests mass loss from the ice-stream catchment that is of sufficient magnitude to reverse the gain estimated for today's Siple Coast region. Analysis of other ice streams would allow comparison of velocities over millennial time scales with observations of present-day velocities, useful for evaluating how West Antarctic ice drainage has evolved. [ABSTRACT FROM AUTHOR]

The Ellsworth–Whitmore Mountains (EWM) are one of five terranes that form West Antarctica. Constraining the positions of these terranes in pre-break up Gondwana is crucial to understanding the history of the palaeo-Pacific Gondwana margin. We report the results of a detailed palaeomagnetic investigation of the EWM, which comprises some 150 sites in six formations, ranging in age from Cambrian to Permian. Five of the studied units yield only viscous remnant magnetizations of recent age, or unstable natural remanent magnetizations. The remaining unit, the mid-late Cambrian Frazier Ridge Formation, yielded stable magnetizations at 16 of 35 sites. This component passes a fold test at the 95 per cent confidence level, indicating that it pre-dates Permian deformation, and we argue that it is of primary origin. The resulting palaeopole (9°N; 293°E; ) is in good agreement with two previously published palaeopoles from similarly aged rocks in the EWM. Collectively these data indicate that the EWM were located in the Natal Embayment prior to Gondwana break-up, and underwent 90° of anticlockwise rotation during break-up. All three studies, however, yield inclinations that are slightly too shallow when compared with coeval Gondwana reference poles. [ABSTRACT FROM AUTHOR]

Describes the dimensions and topographic setting of subglacial lakes in Antarctica. Calculation of the likely total volume of water stored in lakes beneath the Antarctic ice sheet; Implications of the calculation of water volume for the massive flood events; Frequency distributions of ice thickness.

Results of an analysis of the distribution and movement of extratropical cyclones around Antarctica for the period September, 1973, through May, 1975, are presented. Variations in seasonal cyclone frequencies, their preferred longitudinal positions, and the spatial and temporal fluctuations in latitude and pressure are shown, and these indicate good agreement temporal fluctuations in latitude and pressure are shown, and these indicate good agreement with the known features of Southern Hemisphere climatology. The greatest numbers of cyclones occur during spring and fall, and their most common locations are near coastal embayments. A semiannual oscillation is present in the frequencies, mean latitudes, and mean pressures of the cyclones, although to varying degrees. Longitudinal variations in the intensity of the oscillation are also evident. The belt of maximum cyclone activity exhibits a distinct half-yearly cycle in latitudinal position, although the trough is located some 5° north of the position determined from mean monthly pressures. Harmonic analysis of the spatial variation of this belt and the simultaneous position of the sea-ice margin derived from microwave imagery suggests that there is little correlation between sea ice and cyclone tracks on a hemispheric scale. Close relationships are apparent for short time periods or in specific regions but will require more intensive study before causal mechanisms can be suggested. The asymmetry of the continent, rather than the extent of sea ice, is probably the principal factor involved in determining the longitudinal variations in the positions and tracks of cyclones around Antarctica on a hemispheric scale. [ABSTRACT FROM AUTHOR]

The spatial variability of seasonal mean temperature departures at 26 stations around Antarctica, southern South America, and nearby islands is shown using factor analysis. An opposition in temperature anomalies between mainland stations and those on or near the An opposition in temperature anomalies between mainland stations and those on or near the Antarctic Peninsula is a recurring pattern of spatial variability in all seasons but spring. Other factors indicate that temperature anomalies alternate in sign around the continent and especially near the peninsula. The association between the spatial patterns of temperature variability and features of the atmospheric circulation at middle and higher latitudes of the Southern Hemisphere is also examined. In each season the time series of one factor is significantly associated with temporal variations in the strength of the 500 mb westerlies, measured using height differences across six pairs of middle-latitude and Antarctic stations. In winter and summer the westerlies are linked to the mainland/Peninsula temperature opposition pattern such that when zonal flow is anomalously strong, mainland stations are anomalously cold. In autumn and spring, temperature variability is highly related to meridional flow strength over New Zealand and in the lee of the Andes, and is associated with interannual longitudinal shifts in the positions of the climatological lows near the Antarctic coast. A deep Andes trough is associated with longer-than-usual ice duration at the South Orkneys. Historically, strong troughing and heavy sea-ice conditions in the South Atlantic occurred between 1920 and 1935. [ABSTRACT FROM AUTHOR]

Discusses the results of satellite image analysis and fieldwork conducted during the 1994-1995 field season at Simple Dome, Antarctica which aimed to characterize Simple Dome as a potential site for deep ice coring and investigating the history of ice dynamics in the area. Characteristic surface features of ice streams; Focus of global positioning system and optical surveying in the summit area of Simple Dome; Factor which will help constrain models of ice flow for Simple Dome.

Reports trends in the nitrate time series deduced from low-accumulation sites such as Dome C and Vostok in Antarctica. Methods; Results; Discussion.

The article unveils the result of ANDRILL, a US$30 million international drilling project, in Antarctica. The drilling project in the western Ross Sea revealed that the country had more eventful climatic history and the new sediment core showed that the western part of the country went through a prolonged ice-free phases, offering scientists an idea of where the global warming might be heading. During the first two years of their drilling, they extracted two cores which contain some 1,200 metres of sediment from the seabed below the vast Ross Ice Shelf. Scientists believed that the specimen will provide them an uninterrupted 17-million-year record of the country's climatic past. The core revealed how ice retreated rapidly and quickly in the country.

The article presents information on a series of warm episodes, each of which lasted for several thousand years and occurred in Antarctica between 90,000 and 30,000 years ago. This bipolar seesaw have been driven by changes in the strength of the deep overturning circulation in the North Atlantic Ocean, but some have questioned how completely that process can account for the fine details of Antarctic warming events. The changes in the surface salinity gradient across the Antarctic Circumpolar Current were caused by the melting of icebergs discharged from the Arctic, which allowed increased heat transport to Antarctica by ocean eddies. This mechanism produces Antarctic warming of the magnitude observed in ice core records.