and adjacent downslope turbidite gullies. The glacial geology of surrounding areas suggests that an iceshelf probably flowed from the mouths of overdeepened glacial throughs in the Canadian Arctic Archipelago westward along the ABM and across the Chukchi
Borderland. This curved pathway indicates an obstruction to ice flow in the central Canada Basin. Evidence for glaciogenic features on the ABM corrobates suggestions that large ice volumes and extents existed in the Arctic during Pleistocene glacial periods
. These findings have far-reaching implications for Arctic climate studies, ocean circulation, sediment stratigraphy and the stability of circum-Arctic continental ice masses.
masse dans la zone d'influence du courant glaciaire dans le Ronne IceShelf. Les AA. présentent les données et les premiers résultats. - (DR)
Durant l'été austral 1994-95, un programme extensif de mesures glaciologiques, géophysiques et géodétiques a été mené le long d'une ligne d'écoulement du Foundation Ice Stream. Les données collectives servent de base à la détermination du flux de
Late Quaternary ice-surface fluctuations of Beardmore Glacier, Transantarctic Mountains
that the Beardmore drift limit is late Wisconsin (isotope stage 2) and the Meyer limit Stage 6 in age. The Beardmore and Meyer drift sheets represent thickening of the Beardmore Glacier in response to Ross IceShelf grounding during the last two global glaciations
. Ice-shelf grounding most likely resulted from lowered sea level and/or basal melting.
The research strategy of the AA. combines geologic mapping and soil studies of drift sheets in ice-free areas. They differentiated drift sheets by changes in surface morphology, surface boulder weathering and soil development. The AA. conclude
Present-day sedimentary environments in the eastern Weddell Sea confirm low clastic sediment input from wide (> 100 km) ice-shelves. Mainly bioclastic sediments are formed in situ on the inner and shallow central-shelf areas (250 to 350 m water
expansion of grounded ice to the shelf break. Subsequent eustatic rise caused grounded ice to float Frozen-on sediments melted out of the base of the ice, depositing soft pebbly mud above the till-Marine conditions similar to present-day conditions were
depth), with sedimentation rates probably < 0,01 m/ka. The coarse grained texture of these deposits is caused by removal of finer grades in suspension during settling of ice rafted debris sediments. Overconsolidated till was deposited < 31 000 BP during
Reconstruction of ice complex remnants on the Eastern Siberian Arctic shelf
Based on the analysis of seafloor topography together with historical, geological and palaeogeographical data obtained from published and archived sources, this paper is an attempt to reconstruct the history of Ice Complex (IC) islands within
the Laptev and East Siberian Sea shelves. Also, an attempt to estimate the rate of seafloor thermal abrasion was made and a schematic map of former IC islands within the Laptev Sea and western part of the East Siberian Sea shelves has been compiled.
It is suggested that the origin of submarine canyons depends on two factors: 1.a drop of the ocean level below the shelf/slope rim as a consequence of the formation of enormous ice masses during a glaciation. 2. the presence of powerful streams
, created by the melting of ice masses| these streams carried large amounts of glacial debris across the shelf and deposited them on the continental slope. Continuous overloading of these debris piles resulted in debris avalanches downslope, which excavated
Antarctica ; Cold area ; Glacial lake ; Ice sheet ; Lake ; Model ; Palaeo-environment
This paper presents the first test of the captured iceshelf (CIS) hypothesis using field data from a modern ice sheet, by comparing the predicted geometry with that of Lake Vostok, the planet's largest existing sub-glacial lake, situated under
the East Antarctic ice sheet. It is showed that Lake Vostok agrees with this hypothesis. The result also implies that the lake may well be of pre-glacial origin, and that it may have experienced jökulhlaups during previous interglacials.
Observations on submerged glacial ice in McMurdo Sound, Antarctica
restes d'une expansion passée du Ross IceShelf. Leur stratification et les datations font espérer que la chronologie géologique de la glaciation du Sound pourra être établie. L'île s'est détachée du cap entre 1908 et 1956. De larges portions du Ross Ice
Shelf se sont détachées à l'ouest du McMurdo Sound à plusieurs reprises depuis 1908.
It is postulated that variations in atmospheric carbon dioxide acted through an Antarctic iceshelf linked to the grounded ice sheet to produce and terminate Southern Hemisphere ice-age climate. It is further postulated that Milankovitch summer
insolation combined with a warm high-frequency oscillation caused marked recession of Northern Hemisphere ice-sheet melting margins and the North Atlantic polar front about 14,000 14 C yr B.P. This permitted renewed formation of North Atlantic Deep Water
of the interlocked global ice-sheet system, which was at its largest but most vulnerable configuration.
by examining recent efforts (post-2000 publications) to correlate vertical changes in sea level with climate and ice sheet volume, before considering research focused on coastal evolution and shelf sedimentation.
Quaternary science is experiencing something of a revolution. Motivated by the emerging climate records from the ice sheets and the world's ocean, the geographical community is eagerly pursuing a global research agenda. This review begins
Application of tandem accelerator mass-spectrometer dating to late pleistocene-holocene sediments of the East Antarctic continental shelf
deposits (diamictons) are interpreted as maximum ages. The consistency of corrected ages from the shelf, along with the sedimentologic interpretation, suggests a rather recent recession, perhaps mid-Holocene for this portion of the East Antarctic ice sheet
Geomorphology of the onset area of a paleo-ice stream, Marguerite Bay, Antarctic Peninsula
Reconstructing ice-sheet dynamics from subglacial sediments and landforms. Special issue
the Last Glacial Maximum. Ice drainage within the bay and on the inner continental shelf was strongly influenced by tectonic fabric. The glacially sculptured geomorphic features within Marguerite Bay co-exist with anastomosing, radial and relatively
Geomorphic features indicate that both glacial and melt-water erosion characterize the onset area of the ancestral Marguerite Ice Stream. The large size of these features indicates that they formed over repeated glacial cycles, most recently during
Modelling studies of underside of Brunt and Ross ice shelves suggest two main conclusions: 1. Ice-shelves are of major importance for sedimentation on the continental shelf. Bulk debris release occurs within the grounding-line zone which may
frequently oscillate, producing pronounced diachronism. Bottom melting removes all debris prior to calving at the ice front so that, ice shelves do not play a part in deposition in the open ocean| 2. Outlet glaciers, in contrast, have high sediment content
, calve rapidly and produce debris-rich icebergs which contribute the major portion of ice-rafted debris.