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Antarctic shelf-slope dynamics: an innovative geophysical approach

More:  Institutes 
Dutch title: Antarctic shelf-slope dynamics: een vernieuwde geofysische aanpak
Parent project: Research action SPSD-I: Sustainable management of the North Sea, more
Reference no: A4/DD/G01
Period: December 1996 till November 2001
Status: Completed

Thesaurus terms: Coastal waters; Continental margins; Continental shelf; Geophysics; Glacial geology; Ice caps; Seismic reflection profiling
Geographical term: Antarctica [gazetteer]

Institutes (2)  Top 
  • Universiteit Gent; Faculteit Wetenschappen; Vakgroep Geologie en Bodemkunde; Renard Centre of Marine Geology (RCMG), more
  • Belgian Science Policy (BELSPO), more, sponsor

Abstract:
The purpose of this research is the geophysical study - at very high resolution - of the internal structure and evolution of Antarctic continental margins, in order to better understand the relation between firstly the dynamics of the ice cap and, secondly, the processes of sedimentary deposit and remobilisation on the continental slope. It aims at making optimal use of seismic reflection with broadband sources such as sparkers, which were successfully used in the studies performed on large lakes and recently also along the European continental margins.

OBJECTIVES

In accordance with the recommendations of SCAR/ANTOSTRAT, the research will focus on a number of specific scientific objectives:

- on the shelf itself: analysis of possible residual sedimentary deposits as potential evidence of smaller pulsations of the ice cap, which would not have reached the edge of the shelf itself;

- on the outer part of the shelf and the higher parts of the continental slope: the spatial relation between the large zones of progradation of the "trough-mouth fans", deposited in front of the discharge system of large ice flows;

- the spatial and relative chronological relation between the deposits on the continental slope itself and those at the base of the slope;

- the spatial and relative chronological relation between large-scale instabilities (debris flows) on the continental slope and the normal accretion of "trough-mouth fans", in order to be able to determine whether these processes occur in-phase or out-of-phase.

In order to be able to optimally project these processes on an absolute chronology of the glacial evolution of the Antarctic margins, the above-mentioned research efforts will (within the framework of the operational possibilities) be integrated into the new phase of Antarctic ODP activities planned for the coming years.

On the methodological level, these scientific objectives imply the development of a seismic reflection technique which - in the polar waters - will guarantee optimal broadband-characteristics and a maximum signal-to-noise ratio in the useful bandwidth. To this end, at least one of the components of the seismic system - the streamer - will be towed at around 300 meters below the water´s surface, in combination with a surface streamer when weather conditions allow. In a second phase, one also intends to immerse a sparker source, which implies the study of the behaviour of a sparker system in a "subtow" configuration with a long cable length.

Special attention will be paid to examining the possibilities for using this new methodology, particularly in geotechnical site explorations on the continental slope (preparation of drilling sites, study of ground instabilities).

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