ABSTRACT. Talos Dome is an ice dome on the edge of the East Antarctic plateau; because accumulation is higher here than in other domes of East Antarctica, the ice preserves a good geochemical and palaeoclimatic record. A new map of the Talos Dome area locates the dome summit using the global positioning system (GPS) (72˚47' 14''S, 159˚04' 2'' E; 2318.5 m elevation (WGS84)). A surface strain network of nine stakes was measured using GPS. Data indicate that the stake closest to the summit moves south-southeast at a few cm a Airborne radar measurements indicate that the bedrock at the Talos Dome summit is about 400 m in elevation, and that it is covered by about 1900 m of ice. Snow radar and GPS surveys show that internal layering is continuous and horizontal in the summit area (15 km radius). The depth distribution analysis of snow radar layers reveals that accumulation decreases downwind of the dome (north-northeast) and increases upwind (south-southwest).The palaeomorphology of the dome has changed during the past 500 years, probably due to variation in spatial distribution of snow accumulation, driven by wind sublimation. In order to calculate a preliminary age vs depth profile for Talos Dome, a simple onedimensional steady-state model was formulated. This model predicts that the ice 100 m above the bedrock may cover one glacial-interglacial period.

We present the interpretation of 11 radio echo-sounding (RES) missions carried out over the\ud Vostok–Dome Concordia region during the Italian Antarctic expeditions in the period 1995–\ud 2001. The extension and the density of the radar data in the surveyed area allowed to reconstruct\ud a reliable subglacial morphology and to identify four relevant morphological structures namely:\ud the Aurora trench, the Concordia trench, the Concordia ridge and the South Hills. These\ud structures show evidence compatible with the presence of tectonic features. Morphological\ud considerations indicate their development in Cenozoic time. Hybrid cellular automata (HCA)-\ud based numerical modelling allowed to justify a possible role played by the tectonics of the\ud Aurora and Concordia trench evolution. This was accomplished by matching the bed profiles\ud along opportunely projected sections with the modelled surfaces as derived by the activity of\ud normal faults with variable surfaces within the continental crust. The Vostok–Dome C region\ud is characterized by a large number of subglacial lakes. From the analysis of basal reflected\ud power echo, we identified 14 new lakes and obtained information about their physiography as\ud well as their possible relations with tectonics.We propose a grouping of subglacial lakes on the\ud base of their physiography and geological setting, namely relief lakes, basin lakes and trench\ud lakes. Relief lakes located in the Belgica subglacial highlands and are characterized by sharp\ud and steep symmetric edges, suggesting a maximum water depth of the order of 100 m. Their\ud origin may well relate to localized, positive geothermal flux anomalies. Basin lakes located\ud in the Vincennes subglacial basin and are characterized by wider dimension that allow the\ud development of well-defined, flat ice surface anomalies. Trench lakes characterize the Aurora\ud and Concordia trenches as the possible effect of normal fault activity

ZusammenfassungAcht neue seismische Refraktionsprofile in den Nordappenninen und den Ligurischen Alpen wurden berechnet, und zwar in der Fortsetzung von Reflexionsprofilen im Pobecken, die von Bohrungen kontrolliert sind. Diese neuen Refraktionsprofile tragen bei zu einer besseren Erfassung der Untergrundstruktur dieses verwickelten ,,Ligurischen Knotens". Im besonderen haben sie die Abgrenzung von einigen K6rpern hoher Geschwindigkeit erm6glicht, die korrelierbar sind mit gewissen geologischen Einheiten, nfimlich mit dem adriatischen Mesozoikum, den Ophiolithen der appenninischen Liguriden sowie mit den Antolaflysch unterlagernden Ophiolithen und Karbonaten der ligurischen Alpen. Bei der Verbindung der Reflexions-und Refraktionslinien stellt sich heraus, dab die genannten Einheiten hoher Geschwindigkeit durch wichtige Dislokationen getrennt sind: die basale Uberschiebung der Padaniden (PlioPleistocaen), die Villalvernia-Varzi-Linie (OligoMiocaen), die Ottone-Levanto-Linie (Oligo-Miocaen) und den Volpedo-Valle Salimbene-Bruch (Oligo-Miocaen, reaktiviert als Transferbruch im PlioPleistocaen). Die 3D-Geometrie des Ligurischen Knotens ist interpretierbar im Rahmen der regionalen Kinematik. Sie ist vertr~glich mit einem Modell, das eine oligocaen-frfihmiocaene NW-Translation des Adria-Indenters vorsieht, gekoppelt mit einem Einbruch des proven9alisch-ligurischen Beckens und einer Rotation des sardo-ligurischen Komplexes in die nach Osten zurfickweichende adriatische Subduktionszone. Die refraktionsseismischen Berechnungen erstrecken sich nur bis zu einer Tiefe von 15 km; sie werden jedoch erg/inzt durch Daten fiber die Lage der Moho, die ftir die Europ/iische Geotraverse (EGT) erarbeitet wurden. Die Moho scheint in eine Anzahl von Dom/inen zerlegt zu sein, die interpretiert werden k6nnen im Lichte der Zusammensetzung und tektonischen Geschichte der h6heren Krustenteile. Insbesondere scheint die tiefstgelegene Moho-Dom/ine abgeschnitten zu werden durch den Volpedo-Valle Salimbene-Bruch, welcher folglich die ganze Kruste in Mitleidenschaft ziehen wtirde. Abstract

This study presents the interpretation of radio echo-sounding (RES) data collected during the\ud 2003 geophysical campaign of PNRA (Italian National Research Project in Antarctica), which\ud focused on the exploration of the Concordia Trench-Lake system in East Antarctica. The data\ud allow us to identify a new lake (ITL-28) at the southern edge of the Concordia Trench and\ud a series of N–S trending subglacial troughs cutting through the Belgica Highlands. We have\ud mapped the bedrock morphology at 3 km resolution, which led to an improved geographical\ud and geomorphological characterization of the Concordia Trench, Concordia Ridge, Concordia\ud Lake and South Hills. Improved knowledge of the Concordia Trench allowed us to model\ud the 3-D geometry of the Concordia fault, suggesting that it played a role in governing the\ud morpho-tectonic evolution of the bedrock in the Dome C region, and to propose a Cenozoic\ud age for its activity. We recognize the importance of catchment basin morphology in hosting\ud subglacial lakes, and discuss the role played by tectonics, glacial scouring and volcanism in\ud the origin of the trench lakes, basin lakes and relief lakes, respectively

Improved knowledge of geometrical boundary conditions, such as bedrock geometry and surface topography, can contribute significantly to glaciological studies including ice-sheet-flow modelling. Precise thickness and altimetric data allow an estimation of ice-flow direction, the balance velocity and the basal shear stress. These parameters are calculated along a 1160 km profile in East Antarctica using a relationship between shear stress, basal temperature, the Glen flow exponent and a parameter related to strain rate. Strong variations of the flow-law parameters and basal conditions are found to play a major role in the ice-flow pattern. Sliding, anisotropy and longitudinal stress strongly perturb the validity of the law, but their signature can be identified.