A marine geophysical reconnaissance of the

Summary. Magnetic, bathymetric and seismic reflection profiler data are described from the accessible central and eastern parts of the Weddell Sea. The shape consistency of the magnetic anomalies is not good, but the profiles show magnetic lineations trending slightly north of east over almost all of the area surveyed. The lineations are undulating, and a small reflection profiler survey has revealed the presence, in the northern Weddell Sea, of several closely spaced, small-offset fracture zones trending north-west to west-northwest. The amplitude of the fracture zone topography increases northward as the fracture zone orientation becomes more oblique to the gross orientation of the magnetic anomalies. Two synthetic magnetic anomaly profiles, each providing a reasonable fit to the observed anomalies, are used to argue that neither the quality of the data set nor the existing level of understanding of the regional tectonic environment is adequate as yet to support either an unambiguous age for the Weddell Sea or a model for its evolution.