Frontiers and Opportunities in Antarctic Geosciences * Certosa di Pontignano * 29-31 July 2004
GLacial Meltwater and the Sedimentary ARchitecture of High-Latitude
Continental Margins (GLAMAR: International Polar Year, Idea 242)
D. PRAEG
Dept of Geology,University College Dublin, Belfield, Dublin, Ireland (daniel.praeg@ucd.ie)
The advance of an ice sheet is limited by a combination of iceberg calving (along marine or lacustrine margins) and
melting (mainly at the surface), the latter increasing in importance at lower latitudes. The recharge of surface meltwater
to the glacier bed has a critical influence on the dynamics of ice flow and sediment erosion/deposition, due to the
importance of subglacial drainage in the processes of basal deformation and the transport of different sediment types
(sorted vs unsorted) to the glacier margin. Surprisingly, the role of meltwater processes has received little attention in
relation to the glaciation of continental margins. However, the eastern Canadian continental margin contains evidence
of latitudinal control by meltwater processes on its gross sedimentary architecture and seabed morphology (e.g. sloperise canyons at lower latitudes). The NW European margin also displays latitudinal variation in its Quaternary morphostratigraphic character, previously suggested to reflect the varying duration of glaciation, but here proposed to relate to
meltwater processes.
This presentation draws on information compiled along the NW European margin, from Ireland to Lofoten, in the
course of the recent STRATAGEM project (STRATAGEM Partners 2003; Stoker et al. in press; Sejrup et al.,
submitted). This work shows that the onset of shelf-edge glaciation was indeed diachronous, older to the north (ca. 1.5
Ma in the Barents Sea) than to the south (ca. 0.5 Ma west of Britain and Ireland). Along most of the margin, glaciation
resulted in the deposition of (mainly muddy) trough-mouth fans, but in the south the slope west of Ireland lacks such
fans and is incised by canyons. Erosional or depositional records of subglacial drainage are rare in shelf successions
adjacent to the trough-mouth fans, but glaciofluvial palaeo-drainage networks (eskers and tunnel-valleys) are abundant
along the southern margins of the successive European ice sheets, including in and adjacent to Ireland. Examples are
presented from a network of large tunnel-valleys in the southern North Sea, to illustrate the nature of the subglacial
drainage systems that supplied large volumes of meltwater and sandy sediment to the ice sheet margins south and west
of Ireland.
These observations form the basis of a project submitted to the Planning Group of the International Polar Year (IPY
2007-8), proposing to test the hypothesis that spatial variability in the processes of subglacial drainage, through their
influence on the processes of sediment transport and supply to ice sheet margins, may influence the morphological and
stratigraphical development of glaciated continental margins. Specific objectives include:

to model the first-order mass balance of a generic marine ice sheet, in order to constrain the possible
latitudinal variation in meltwater supply to a continental margin

to undertake a comparative morpho-stratigraphic analysis of the North Atlantic margins (NW Europe, Greenland
and eastern Canada) in response to the late Quaternary (≤0.7 Ma) expansion of northern hemisphere glaciation, in
order to relate subglacial sediment systems on the shelves to major zones of glaciofluvial (i.e. meltwater and sand)
input on the continental slopes

to consider the implications of identified spatial variability in meltwater input into the North Atlantic for late
Cenozoic climate variability

to compare the results from the North Atlantic margins with selected parts of the eastern vs western Antarctic
margin where meltwater is of greater and lesser importance, in order to assess whether late Cenozoic spatial (or
temporal) variability in subglacial processes has been significant
INTERNATIONAL COLLABORATION:
Torbjørn Dahlgren, Department of Geology, University of Tromsø (UiT), Norway
Laura Desantis, Istituto Nazionale di Oceanografia e Geofisica Sperimentale (OGS), Trieste, Italy
Richard Hindmarsh, British Antarctic Survey (BAS), Cambridge, UK
Berit Hjelstuen, Department of Earth Science, University of Bergen (UiB), Norway
Tove Nielsen, Geological Survey of Denmark and Greenland (GEUS), Copenhagen, Denmark
David Piper, Geological Survey of Canada-Atlantic, Bedford Institute of Oceanography, Canada
Patrick Shannon, Department of Geology, University College Dublin
Martyn Stoker, British Geological Survey, Edinburgh, UK
REFERENCES
Sejrup, H.-P., Hjuelstuen, B.O. , Dahlgren, T., Haflidason, H., Kuijpers, A., Nygård, A., Praeg, D., Stoker, M.S. & Vorren, T., in prep. Pleistocene
glacial history of the NW European continental margin. Marine & Petroleum Geology, thematic issue (P.M. Shannon & M.S. Stoker, eds), to be
published 2005.
Stoker, M.S., Praeg, D., Shannon, P.M., Hjelstuen, B.O., Laberg, J.S., Nielsen, T., van Weering, T.C.E., Sejrup, H.P. & Evans, D., in press. Neogene
evolution of the Atlantic continental margin of NW Europe (Lofoten Islands to SW Ireland): anything but passive. In Petroleum Geology: NorthWest Europe and Global Perspectives - Proceedings of the 6th Petroleum Geology Conference (Dore, A.G. & Vining, B., eds); The Geological
Society, London (to be published in early 2005).
STRATAGEM Partners, 2003. Neogene Evolution of the Glaciated European Margin (M.S. Stoker, compiler). A product of the EC-supported
STRATAGEM project, contract EVK3-CT-1999-00011; Svitzer Ltd, Great Yarmouth, UK, 165 pp.