A marine geophysical investigation of the continental margin of east Greenland (63(^º)n to 69(^º) n)

Abstract

During late July and August 1977, a marine geophysical investigation of the continental margin off East Greenland between latitudes 63(^º)N and 69.1(^º)N was undertaken by the University of Durham using the research vessel, R.R.S. Shackleton. Nearly 3500 km of continuously recorded bathymetric, magnetic and gravity data and approximately 2000 km of multi-channel seismic reflection data were recorded in a series of nearly parallel profiles perpendicular to the assumed strike of the continental margin. Disposable sonobuoy work was also carried out. The reduction, processing and interpretation of the geophysical data are described. In particular, the application of the maximum entropy method (MEM) of spectral estimation (using Burg's algorithm) to the problem of estimating the depth to buried magnetic sources is assessed. The principal geophysical results include: 1. The location of the ocean-continent boundary is inferred Fran seismic reflection data and the recognition of marine magnetic anomalies. Oceanic anomalies 22 through 24 are truncated by the continental margin. The marine anomaly sequence 13 through 21 is tentatively extrapolated northwards through the Denmark Straits and stops against the Denmark Straits fracture zone. 2. It is proposed that the Tertiary plateau basalts of the Blosseville coast do not terminate abruptly offshore but are down-faulted and continue eastwards, overlain by a prograded sequence of Tertiary sediments. 3. An interpretation of one processed, GDP stacked seismic section north of the Greenland-Iceland Ridge is presented. Several unconformities are recognised on the basis of seismic stratigraphic analysis. Two seismic horizons showing distinctive of flap against oceanic basement are tentatively dated at 30 Ma and 22 Ma respectively. No evidence is found for the presence of Mesozoic sediments offshore. 4. Gravity modelling indicates that the prograded wedge of Tertiary sediments observed north and south of the Greenland-Iceland Ridge is not isostatically compensated.